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GONIOSCOPY A Text and Atlas
(with Goniovideos)
GONIOSCOPY A Text and Atlas (with Goniovideos) Second Edition TANUJ DADA MD Additional Professor Dr Rajendra Prasad Centre for Ophthalmic Sciences All India Institute of Medical Sciences New Delhi, India
REETIKA SHARMA MD Senior Registrar Dr Rajendra Prasad Centre for Ophthalmic Sciences All India Institute of Medical Sciences New Delhi, India
AMIT SOBTI MD Senior Registrar Dr Rajendra Prasad Centre for Ophthalmic Sciences All India Institute of Medical Sciences New Delhi, India
Foreword ROBERT RITCH
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Website: www.jaypeebrothers.com Website: www.jaypeedigital.com © 2013, Jaypee Brothers Medical Publishers All rights reserved. No part of this book may be reproduced in any form or by any means without the prior permission of the publisher. Inquiries for bulk sales may be solicited at: [email protected] This book has been published in good faith that the contents provided by the authors contained herein are original, and is intended for educational purposes only. While every effort is made to ensure accuracy of information, the publisher and the authors specifically disclaim any damage, liability, or loss incurred, directly or indirectly, from the use or application of any of the contents of this work. If not specifically stated, all figures and tables are courtesy of the authors. Where appropriate, the readers should consult with a specialist or contact the manufacturer of the drug or device.
Gonioscopy: A Text and Atlas (with Goniovideos) First Edition: 2006 Second Edition: 2013 ISBN : 978-93-5090-434-3 Printed at
Dedicated to The Soldiers of the Indian Army and their families who have performed the supreme sacrifice for the nation “When You Go Home, Tell Them Of Us And Say For Your Tomorrow, We Gave Our Today” —The Kohima poem
Foreword Adequate gonioscopy is crucial for the diagnosis and treatment of glaucoma. Unfortunately, even today, many ophthalmologists do not perform gonioscopy or do not perform it accurately. Indentation gonioscopy in a totally darkened room with a small beam of light is necessary to determine whether an angle is occludable, since light shining in the pupil can open the angle due to the pupillary reflex. In addition, after iridotomy, indentation gonioscopy is necessary to determine whether any remaining appositional closure exists and to differentiate appositional closure from synechial closure. In eyes with open angle glaucoma, familiarity with the angle structures, from the iris insertion, ciliary body band, scleral spur, pigmented meshwork, non-pigmented meshwork, and Schwalbe’s line, when visible, is necessary when performing laser trabeculoplasty and ab interno for surgical procedures involving the trabecular meshwork. Failure to recognize the appropriate landmarks can result in failure of a procedure or complications. This gonioscopy book by Dada et al gives an excellent overview of the features of the angle visible gonioscopically, and covers techniques of direct and indentation gonioscopy, gonioscopic grading systems, and an overview of findings in congenital and developmental glaucomas, angle closure, primary open angle glaucoma, and various secondary glaucomas. The inclusion of goniovideos is a unique feature of this book which provides a video-assisted skill transfer to the trainee ophthalmologist. I am sure that this book will be a priceless asset to residents learning gonioscopy and general ophthalmologists who wish to have improved familiarity with the techniques and findings on gonioscopy found in many different clinical entities.
Robert Ritch MD Shelley and Steven Einhorn Distinguished Chair Professor of Ophthalmology Surgeon Director and Chief, Glaucoma Services The New York Eye and Ear Infirmary New York, USA
Preface Gonioscopy is the current “Gold Standard” for viewing and imaging the anterior chamber angle. It is a simple technique of vital importance for the correct diagnosis of various forms of glaucoma. In ideal situations, a gonioscopic view of the angle may be obtained atleast once in all patients visiting the outpatient services of an ophthalmology clinic, like other routine eye examinations including direct ophthalmoscopy and slit lamp biomicroscopy. However, it is mandatory to perform gonioscopy in all cases of suspected or established glaucomatous pathology. The ground reality is that gonioscopy is seldom performed by the general ophthalmologists and glaucoma treatment is often started without documentation of the anterior chamber angle. A lack of adequate training in gonioscopy in residency programmes is perhaps an important cause for this lapse. The current text and atlas offers a unique learning source to the reader as it covers basic principles, indications and techniques for performing gonioscopy, highlights goniopathologies in congenital and acquired conditions and includes goniovideos to give a near “hands on” experience to the trainee ophthalmologist. We hope that this book will impart practical training which can be put to immediate use in the clinic and help in improving the standard of care of glaucoma patients worldwide.
Tanuj Dada Reetika Sharma Amit Sobti
Acknowledgements I would like to thank my parents Drs Kamlesh and Vijay Kumar Dada for their unconditional love and inspiration. This work has only been possible with their blessings. A special word of gratitude for my soul mate Geeta and little angel “Josya” who add a deep meaning to the journey of my life. I wish to thank my young co-authors Drs Amit Sobti and Reetika Sharma for their dedication and hard work. Working with them has been a proud priviledge. I would like to mention the time and effort put in by two exceptional people who are among the best senior residents ever to cross the gates of Dr RP Centre for Ophthalmic Sciences – Dr Rajamani Muralidhar (presently a consultant at Aravind Eye Hospital Madurai) and Dr Vivek Dave (working at Netra Mandir Hi-Tech Eye Institute, Mumbai). This project has taken a decade and they have been with me all along. I would like to thank Prof RV Azad, Chief, Dr Rajendra Prasad Centre for Ophthalmic Sciences for his constant support and exceptional leadership and my teachers Prof Anita Panda, Prof SP Garg and Prof. Ramanjit Sihota. I wish to express my humble gratitude to “Bob” Ritch for gracing this book with his foreword and thank Prof Robert Weinreb and Prof Kuldev Singh for their constant encouragement in my academic pursuits.
Rajamani Muralidhar
Vivek Dave
The wide collection of goniophotographs and videos could not have been possible without the support of Mr Ajay Sharma who maintains the state of the art glaucoma facility at our centre. I would also like to thank the following residents of Dr Rajendra Prasad Centre for Ophthalmic Sciences who have helped me at all times during this project: Drs Mathew James, Dewang Angmo, Neha Chaturvedi, Vishal Arora, Saurabh Sharma Tarun Arora, Anubha Rathi, Bhaskar Jha, Nagesh BN, Sridevi Nair and Manthan Hasmukhwala. A special word of thanks for Dr Meenakshi Wadhwani, Senior Research Associate, and Mr Sanjeev, Lab Attendant, who work with dedication and go out of the way to help the poor and needy patients visiting our hospital. Last but not least, I express my humble gratitude to my patients, who provide us the opportunity for learning and service and to the divine hand who works through us for alleviating the suffering of humanity.
Tanuj Dada
Contents Gonioscopy Text
Chapter Chapter Chapter Chapter
1 History 2 Principle of Gonioscopy 3 Indications of Gonioscopy 4 Direct and Indirect Gonioscopy
3 5 7 11
Direct Gonioscopy 11 Indirect Gonioscopy 14
Chapter 5
Slit Lamp Gonioscopy Techniques
19
Gonioscopy with Scleral Lenses (Goldmann) 19 Gonioscopy with Corneal Lenses (Posner/Zeiss) 21
Chapter 6
Special Gonioscopy Techniques
23
Manipulative Gonioscopy 23 Indentation Gonioscopy 26 Biometric Gonioscopy 27
Chapter 7
Normal Gonioscopy Anatomy
29
The corneal wedge-localizing the Schwalbe’s line 29 Iris 30 Iris Processes 30 Ciliary Body Band 31 Scleral Spur 31 Trabecular Meshwork 33 Schlemm’s Canal 33 Schwalbe’s Line 34 Normal Blood Vessels 34 Other Regions 35 Determination of Angle Width 35 Recording 36 Difficulties and Artifacts in Gonioscopy 36
Chapter 8
Gonioscopic Grading Systems
37
Shaffer’s System 37 Scheie System 38 RPC Classification 38
Chapter 9
Assessment of Angle Pathology – An Overview Protocol for Evaluation of Angle Structures 41 A Brief Overview of Angle Pathology 41
41
14
GONIOSCOPY: A TEXT AND ATLAS
Chapter 10
Primary Angle Closure Disease
43
Occludable Angle 43 Chronic Primary Angle Closure Glaucoma 46 Plateau Iris Configuration 47
Chapter 11
Primary Open Angle Glaucoma
49
Anatomy of Open Angle 49
Chapter 12
Congenital and Developmental Glaucoma
53
Primary Congenital Glaucoma 53 Axenfeld-Rieger Syndrome 54 Aniridia 54 Irido-Fundal Coloboma 57
Chapter 13
Angle Pathologies
59
Neovascular Glaucoma 59 Iridocorneal Endothelial (ICE) Syndrome 60 Lens Induced Glaucomas 62 Pseudoexfoliation Syndrome 63 Pigment Dispersion Syndrome 64 Uveitic Glaucoma 65 Post-traumatic Glaucoma 66 Neoplastic Activity 75 Glaucoma after Anterior Segment Surgery 76 Elevated Episcleral Venous Pressure Induced Glaucoma 82 Post Surgical Evaluation of Anterior Chamber Angle 82 Glaucoma Drainage Devices 84
Chapter 14
Sterilization of Gonioscopes
87
Ideal Sterlization Method 87 Cleaning and Sterilization: Points to Remember 87 Common Errors while Performing Gonioscopy 87
Chapter 15
RetCam Gonioscopy
89
Open Angle
95
Myopia
97
Angle Closure
98
Closed Angle Opening on Manipulation
99
Anterior Iris Insertion
103
Angle Recession
104
Aniridia
106
Gonioscopy Atlas
Contents
Anterior Chamber Intraocular Lens
108
Axenfeld-Rieger Syndrome
109
Blood in the Angle
112
Ciliary Body Melanoma
113
Corneal Wedge
115
Cotton Fibers in the Angle
116
Cyclodialysis
117
Express Implant
119
Fibrous Ingrowth
121
Foreign Body in the Angle
122
Goniosynechiae
123
Haptic of PC IOL in Angle through Iridectomy
124
Iridodialysis
125
Irido-fundal Coloboma
126
Iris Adherent to Cataract Surgical Wound
127
Iris Bombe
128
Iris PE Cyst Causing Segmental Angle Closure
129
Kayser–Fleischer Ring
130
Neovascularization of Angle
131
Ocular Ischemic Syndrome
133
Pigment Dispersion Syndrome
134
Plateau Iris Configuration with Double Hump Pattern
137
Post Cataract Surgery Gonioscopy
138
Post Surgical Angle Pigmentation
139
Post-traumatic Iridodialysis with Central PAS
141
Post-traumatic Angle Pigmentation
142
Prominent Iris Processes
144
Prominent Schwalbe’s line
146
Pseudophakia with Glaucoma
149
Pseudophakia with Glaucoma with AC IOL
151
Pseudotrabecular Meshwork in a Closed Angle
153
Sarcoidosis Nodules in the Angle
154
15
16
GONIOSCOPY: A TEXT AND ATLAS
Secondary Angle Closure due to High Vaulted ICL
155
Sentinel Synechiae
156
Silicone Oil
157
Trabeculectomy Ostium
158
Uveitic Glaucoma
162
Vitreous Strands in the Angle
164
View of Ciliary Body and Peripheral Retina
166
Ahmed Glaucoma Valve
167
Index
169
Gonioscopy text
Chapter 1
History
The term “gonioscopy” is derived from the Greek words go–’ne– (angle) and o˘ s’k -pe– (view). It is a clinical biomicroscopic technique of examining the angle of the anterior chamber of the eye with the use of a special contact lens known as the gonioscope. It was Alexios Trantas in 1907 (Table 1.1), who first visualized the angle in a living eye, in a case of keratoglobus by indenting the limbus. In his paper, he described the angle of the anterior chamber as seen with and without digital pressure with a direct ophthalmoscope using positive lens
powers.1 Trantas also coined the term gonioscopy. The Goniolens was introduced by Maximilian Salzmann in 19142 wherein he used a scleral contact lens with a corneal radius of 7–8 mm. Salzmann described a variety of normal and pathologic findings in the angle including peripheral anterior synechiae and angle recession. He is called “the father of gonioscopy”. Curran, in 1920, observed that shallowing of the anterior chamber was due to forward bulging of the iris caused by accumulation of aqueous behind the iris.3 Thorburn, a
e
Table 1.1 History of Gonioscopy Names
Years
Description
Trantas
1907
First to visualize the angle. Coined the term gonioscopy
Salzmann
1914
Introduced the goniolens. “The father of gonioscopy”
Curran
1920
Described the mechanism of anterior chamber shallowing
Elsching
1923
Described cyclodialysis cleft. First comprehensive book on gonioscopy
Thorburn
1927
First to photograph the angle. Described the effect of drugs on intraocular pressure
Troncoso
1930
Clarified the anatomic terminology of the structures of the angle and their identification on gonioscopy
Barkan
1936
Coined the term “open angle glaucoma”. Suggested that sclerosis of the trabecular meshwork was the cause of raised intraocular pressure
Goldmann
1938
Described the gonioprism
Kronfeld
1941
Described glaucoma due to synechiae and gonioscopic changes associated with miotics and mydriatics
Sugar
1941
Role of mechanical factors in angle closure glaucoma and study of pigmentary glaucoma
Allen
1945
Development of indirect goniolens
Francois
1948
Use of the term pigmentary glaucoma due to gonioscopic examination
Shaffer and Tour
1956
Described gonioscopy techniques and angle grading
Scheie
1957
Proposed Scheie’s gonioscopy angle grading
Busacca
1964
Correlation between histopathology and gonioscopy
Forbes
1966
Gave the description of indentation gonioscopy with the Zeiss 4 mirror lens
Spaeth
1971
Proposed the Spaeth grading of the angle
Hager
1972
Use of laser trabeculopuncture
Sussman
1979
Introduced the Sussman goniolens
Ritch
1985
Developed the Ritch’s Trabeculoplasty lens
Mizuno
1988
Developed the “trabeculens”
Congdon
1999
Developed biometric gonioscopy
4
Gonioscopy: A Text and atlas
Swedish clinician, did extensive work in peripheral anterior synechiae and angle closure and was the first to photograph the angle in 1927.4 He observed that intraocular pressure rises with atropine instillation and decreases with miotics. He thus hypothesized that the peripheral iris may be blocking aqueous egress. Manuel Troncoso clarified the anatomic terminology of the structures of the angle and their identification on gonioscopy.5 In 1936, Otto Barkan made an important contribution through his gonioscopic classification of glaucomas into open angle and closed angle glaucomas and he was the first to find a true clinical implication of gonioscopy by performing goniotomy in case of congenital glaucoma. He coined the term “open angle glaucoma” and suggested that sclerosis of the trabecular meshwork was the cause of raised intraocular pressure.6 The gonioprism was described by Goldmann in 1938.
Gradle and Sugar were the first ones to try and quantitate the angle configuration in 1940, a goal not yet reached. In 1956, Shaffer and Tour described various gonioscopy techniques which hold good to date.7 Scheie8 proposed a classification for angle grading by gonioscopy in 1957. Forbes in 1966 gave the description of pressure gonioscopy with the Zeiss 4 mirror lens. Spaeth, in 1971 developed a new classification of the angle structures.9 In 1979, Sussman introduced the Sussman goniolens which was a directly held four mirror goniolens.10 Ritch in 1985 developed the Ritch trabeculoplasty lens which is useful for diagnostic gonioscopy as well as for trabeculoplasty and iridotomy.11 The “trabeculens” was developed by Mizuno which was a further modification of the Ritch lens.12 Congdon in 1999 developed biometric gonioscopy which is a technique of objective measurement of the anterior chamber angle using a slit lamp mounted reticule.13
■■References 1. Trantas A. L’ophthalmoscopie de l’angle iridocorneen (gonioscopie). Conclusions a entirer pour la nature du canal de Schlemm Arch Ophthalmol (Paris) 1918;36:257.
8. Scheie HG. Width and pigmentation of the angle of the anterior chamber. A system of grading by gonioscopy. Arch Ophthalmol 1957;58:510.
2. Salzmann M. Die Ophthalmoskopie der Kammerbucht. Z Augenheilk 1914;31:1.
9. Spaeth GL. The normal development of the human anterior chamber angle: a new system of descriptive grading. Trans Ophthalmol Soc UK 1971;XCI:709.
3. Curran EJ. A new operation for glaucoma involving a new principle in the etiology and treatment of chronic primary glaucoma. Arch Ophthalmol 1920;49:131. 4. Thorburn T. A gonioscopical study of anterior peripheral synechiae in primary glaucoma. Arch Ophthal 1933;10:615–20. 5. Troncoso MU. Treatise on Gonioscopy. Philadelphia FA Davis 1947. 6. Barkan O, Boyle SF, Maisler S. On the genesis of glaucoma. An improved method based on slit lamp microscopy of the angle of the anterior chamber. Am J Ophthalmol 1936;19:209–15. 7. Shaffer RN, Tour RL. A comparative study of gonioscopic methods. Am J Ophthalmol 1956;41:256–265.
10. Sussman W. A new instrument for gonioscopy. Ophthalmology 1979;86:130. 11. Ritch R. A new lens for argon laser trabeculoplasty. Ophthalmic Surg 1985;16:331. 12. Mizuno K. A new multipurpose goniolens. Arch Ophthalmol 1988;106:1309. 13. Congdon NG, Spaeth GL, Augsburger J et al. A proposed simple method for measurement in the anterior chamber angle: Biometric Gonioscopy. Ophthalmol 1999;106:2161–2167.
Chapter 2
Principle of Gonioscopy
The anterior chamber angle is formed between the peripheral part of the cornea and the periphery of the iris and is not visible on routine clinical examination. It is not possible to view the iridocorneal angle of the normal eye directly. This can be viewed only by gonioscopy. Gonioscopy is based on the principle of “total internal reflection”. Total internal reflection is an optical phenomenon that occurs when a ray of light strikes a medium boundary at an angle larger than the critical angle with respect to the normal to the surface. If the refractive index is lower on the other side of the boundary, no light can pass through and all of the light is reflected (Figure 2.1). The critical angle is defined as the angle of incidence above which total internal reflection occurs. When light crosses a boundary between materials with different refractive indices, the light beam will be partially refracted at the boundary surface, and partially reflected. But if the angle of incidence is greater (i.e. the ray is closer to being parallel to the boundary) than the critical angle — the angle of incidence at which light is refracted such that it travels along the boundary — then the light will stop crossing the boundary altogether and instead be totally reflected back internally. This can only occur where light travels from a medium with a higher refractive index to one with a lower refractive index. Consider Figure 2.1. In this figure, n1 is a higher refractive index material as compared to n2. At a smaller angle of incidence θ1, the light is partially refracted and is partially reflected back. As the angle of incidence increases, there reaches a particular value say θ 2, where the angle of incidence is such that no amount of light is refracted to the
other side and all light is reflected back towards the first medium. As objects are physically visible when light rays emanating from them fall on the retina, in this case no light rays will reach the retina of the observer who is on the other side and hence the object is not seen. In the eye, total internal reflection occurs at a critical angle of 46 degrees at the air cornea interface.1 Thus light rays coming from the anterior chamber angle exceed this critical angle and are reflected back (Figure 2.2) into the anterior chamber, thereby preventing visualization of the angle (there is a rare exception to this rule—in eyes with a very steep cornea and a deep anterior chamber like keratoglobus and keratoconus where the angle structures may be directly visualized). A gonioscope facilitates examination by obviating the air cornea interface (Figure 2.3), thereby allowing light from the angle to exit the eye. In a direct goniolens, the light emanating from the angle is refracted out of the eye as the rarer medium of air is replaced by the denser medium of the goniolens at the air lens interface. Since the index of refraction of the contact lens approaches that of the cornea, there is very little refraction at the interface between these two media, which eliminates the optical effect of the front corneal surface. In an indirect goniolens, there is a reflecting mirror in the lens (gonioprism). Hence the light rays emanating from the angle reflect at the opposite mirror and are visualized as a reflected image. The image is reflected from the opposite mirror. Hence in an indirect goniolens the examiner sees the angle opposite to the position where the mirror is located.
Figure 2.1 Principle of gonioscopy—total internal reflection
Figure 2.2 Total internal reflection in the eye
6
Gonioscopy: A Text and atlas
Figure 2.3 Use of the gonioscope eliminates the corneal optical power allowing the light rays from the angle to pass through the new lens-air interface
■■Reference 1. Rubin ML. Optics for Clinicians, 2nd edition. Gainsesville, FL. Triad Scientific Publishing, 1974 pp. 56.
Chapter 3
Indications of Gonioscopy
Gonioscopy is an invaluable tool in diagnosing and planning management for glaucoma cases. As a rule gonioscopy should be performed in all cases of diagnosed or suspected glaucoma. Failure to perform gonioscopy is one of the prime reasons for glaucoma misdiagnosis. The purpose of gonioscopy is to determine the topography of the anterior chamber angle. Gonioscopy has both diagnostic and therapeutic uses. One of the most common indications for performing gonioscopic examination is to identify angles at risk of closure and distinguish between primary angle closure and open angle glaucoma (Table 3.1). The traditional van Herick test provides a reliable and valid estimate of the angle width.1 Gonioscopy is indicated in all the cases where the van Herick test shows the angle width to be 0.3 times the corneal thickness or less or where the iris shadow test demonstrates shallow anterior chamber.2 Gonioscopy identifies eyes at risk of angle closure, an important prerequisite before dilating a predisposed patient which also has implications on the treatment. Most cases of angle closure are due to pupillary block. In such cases meticulously performed gonioscopy with indentation can identify closed angles and differentiate synechial closure from appositional closure, thus determining which ones are likely to benefit with laser peripheral iridotomy which often is the only definitive treatment required in such cases. Gonioscopy helps us to identify developmental anomalies in the anterior chamber angle. In cases of Axenfeld Rieger syndrome, gonioscopy assists in evaluating the amount of angle that is closed by peripheral anterior synechiae which can help determine a prognosis for such cases. In cases with aniridia, gonioscopy can help identify the rudimentary stump of the iris in the angle. Angle abnormalities leading to a secondary glaucoma are also easily identified with gonioscopy. One can visualize new vessels in neovascular glaucoma, pigment and debris in pseudoexfoliation and pigment dispersion glaucoma, angle recession and angle foreign bodies in cases of trauma, copper deposition on Descemet’s membrane (Figures 3.1–3.4) in Wilson disease, anterior segment tumors, vitreous strands, etc. The gonioscope also aids in assessing the fistula created during glaucoma filtering procedure, documenting any obstruction to it and studying the patency of laser iridotomy. Diagnostic gonioscopy is a dynamic procedure. It is important to remember that the anatomy of the angle can be
Table 3.1 Indications for Gonioscopy2
Diagnostic • All cases of suspected angle closure either on the iris shadow test or the van Herick test • To study topography of the anterior chamber angle • To assess degree of opening of anterior chamber angle recess • To assess risk of closure on dilatation of pupil • Visualization of congenital anomalies • Classification of Glaucoma (primary/secondary) • To note the presence and extent of angle neovascularization • Assessment of abnormal angle pigmentation • Visualization of pseudoexfoliative material in the angle • To look for post-traumatic angle recession, cyclodialysis • Rule out foreign body in the angle after open globe injury • Neoplastic invasion into angle structures (ciliary body tumor) • Diagnosis of epithelial down-growth • To look for vitreous strands incarcerated in the surgical wound • To view copper deposition on Descemet’s membrane • To study patency of trabeculectomy fistula • To view a peripheral laser iridotomy • To visualize the internal ostium of a glaucoma drainage device • To see orientation of haptics of an anterior chamber IOL Therapeutic • • • • • • •
Laser trabeculoplasty Excimer laser trabeculotomy Goniotomy/gonioplasty Laser goniophotocoagulation Reopening of a blocked trabeculectomy opening Nd-YAG laser after deep sclerectomy Laser of suture tied around tube of a glaucoma drainage device • Indentation gonioscopy to break an acute attack of PACG
8
Gonioscopy: A Text and atlas
Figure 3.1 Kayser Fleischer Ring in Wilson’s disease on gonioscopy
Figure 3.2 Kayser Fleischer Ring in Wilson’s disease on gonioscopy
Figure 3.3 Kayser Fleischer Ring in Wilson’s disease on slit lamp examination showing the level of deposition
Figure 3.4 Kayser Fleischer Ring in Wilson’s disease on slit lamp examination
altered by surgery, time and drugs and therefore gonioscopy may need to be repeated on a regular basis during the long term follow-up of a glaucoma patient. In addition to its various diagnostic uses, gonioscopy is also used for therapeutic purposes when performing procedures like goniotomy, laser trabeculoplasty, goniophotocoagulation, etc. In argon laser trabeculoplasty or selective laser trabeculoplasty, an indirect goniolens like a Ritch trabeculoplasty lens or a Goldmann three mirror or a one mirror lens is used to reflect the laser beam on the pigmented trabecular meshwork to decrease the intraocular pressure. Indentation gonioscopy may sometimes be successful in breaking an attack of angle closure glaucoma. In general, gonioscopy is contraindicated (Table 3.2) whenever there is any suspicion of an open globe injury or immediately after a concussion injury as pressure on the globe can aggravate the injury caused to ocular tissues. Examination is also to be avoided in the early postoperative period after any intraocular surgery and in cases with traumatic hyphema until the blood has cleared to permit
Table 3.2 Contraindications for gonioscopy
• • • •
Active keratitis or conjunctivitis Dense limbus to limbus corneal scars Hyphema Collagen vascular disorders with corneal melts or peripheral ectasias • Corneal epithelial defects • Immediate postoperative period • Globe perforation
an adequate view of the angle structures. One should avoid gonioscopy if the eye has a corneal abrasion or an external ocular infection. Gonioscopic examination is an important tool in the examination of patients with ocular disorders and must be incorporated into the routine ophthalmic evaluation as a standard protocol. An incorrect diagnosis is often made if
Indications of Gonioscopy
one omits to examine the anterior chamber angle, resulting in improper therapy. The gonioscopic evaluation provides a clear insight into the pathogenesis of the glaucomatous pathology and facilitates appropriate medical, laser and surgical treatment. Mastering gonioscopy is also a necessary requirement for the performance of laser procedures on the angle structures. Competent performance of gonioscopy
is an art and science acquired only through experience as it requires considerable eye-hand coordination and knowledge of the normal and abnormal gonio-anatomy and the ability to avoid artifactual observations. All ophthalmologists must acquire training in the art of gonioscopy and perform it regularly in their outpatient service.
■■References 1. van Herick W, Shaffer RN. Estimation of width of angle of anterior chamber. Incidence and significance of the narrow angle. Am J Ophthalmol 1969;68:626–9.
2. Vargas E, Drance SM. Anterior chamber depth in angle closure glaucoma: clinical methods of depth determination in people with and without the disease. Arch Ophthalmol 1973;90(6):438–9.
9
Direct and Indirect Gonioscopy
Chapter 4
Gonioscopy is broadly classified into two categories: Direct and Indirect (Table 4.1). 1 Each technique has its own advantages and disadvantages and uses a different type of gonioscope. The direct method utilizes a domed gonioscope with a direct visualization (Figure 4.1) through a hand held biomicroscope and a separate light source with the patient in supine position. An operating microscope may also be used to visualize the angle structures during direct gonioscopy. The indirect method utilizes a gonioscope with a mirror (Figure 4.2) to obtain an inverted view of the angle structures and is conveniently performed with the patient sitting at the slit lamp.2 This indirect method is currently the most popular technique of gonioscopy as it is very easy to use, the patient is comfortably seated and one obtains an excellent, high magnification view on the slit lamp optics.3,4 The direct method is mostly used during examination of infants under sedation or general anesthesia and during surgical procedures such as goniotomy.
■■Direct Gonioscopy A steeply convex lens is used that permits light from the iridocorneal angle to exit the eye closer to the perpendicular at the interface between the lens and the air. The Koeppe lens (Figures 4.3–4.5) is the prototype diagnostic goniolens which is used for direct gonioscopy. It is a +50 D lens, made of Barium crown glass or plastic with an inner radius of curvature of 7.5 mm and an outer radius of 12.5 mm, which
is placed on the cornea with the patient in supine position. Saline is used to bridge the gap between the lens and the cornea and it acts as an optical coupler between the two surfaces. A hand-held binocular microscope (Figures 4.6 and 4.7) is used that is counterbalanced to permit the ease of handling. Illumination is provided by a separate light source held in the examiner’s other hand. The 1.5x magnification of the Koeppe’s lens coupled with the 16x magnification of the oculars yields a total magnification of 24x. We usually employ the operating microscope with two lenses placed simultaneously on each eye separately, to allow direct assessment and comparison between the two eyes. With this technique one gets an ERECT VIEW of the angle structures, which is essential when performing goniotomies. The examiner has to shift position to get a 360 degree view of the angle. These lenses are available in different diameters and radii of posterior curvatures to accommodate different sized eyes. Koeppe lenses are available in sizes ranging from 16–22.5 mm in diameter. Most adults can be examined with 16 or 18 mm lens, but a larger diameter lens should be used if the limbus is irregular or a filtering bleb is present. Fundoscopy can also be performed through these lenses when using a direct ophthalmoscope and a high plus power lens and is of use in eyes with miotic pupils or cloudy media. Other lenses which may be used are the Swan-Jacob’s lens (Figures 4.8 and 4.9) which has a handle, especially useful while performing goniotomies, the Barkan lens, Worst and Richardson lenses.
Table 4.1 Contact Lenses for Gonioscopy
I. Direct Gonioscopes
II. Indirect Gonioscopes
Lens
Description and Use
1.
Koeppe
Prototype diagnostic goniolens
2.
Richardon-Shaffer
Small Koeppe lens for infants
3.
Layden
For premature infant gonioscopy
4.
Barkan
Prototype surgical lens
5.
Thorpe
Surgical and diagnostic lens
6.
Swan-Jacob
Surgical goniolens for children
1.
Goldmann single-mirror
Mirror inclined at 62° for gonioscopy
2.
Zeiss four-mirror
All four mirrors inclined at 64° for gonioscopy; requires holder (Unger); fluid bridge not required
3.
Posner four-mirror
Modified Zeiss four-mirror gonioprism with attached handle.
4.
Sussman four-mirror
Hand-held Zeiss-type gonioprism
5.
Thorpe four-mirror
Four gonioscopy mirrors, inclined at 62°, requires fluid bridge
6.
Ritch trabeculoplasty lens
Four gonioscopy mirrors; two inclined at 59° and two at 62°
12
Gonioscopy: A Text and atlas
Figure 4.1 Direct Gonioscopy
Figure 4.2 Indirect Gonioscopy
Figure 4.3 Koeppe Goniolenses of different diameters
Figure 4.4 Koeppe lens
Figure 4.5 Gonioscopy being done under anesthesia
Direct and Indirect Gonioscopy
Figure 4.7 Gonioscopy being done under anesthesia using hand-held biomicroscope
Figure 4.6 Gonioscopy being done under anesthesia using operating microscope
Fig. 4.9 Gonioscopy being performed under anesthesia using Swan Jacob lens—pediatric surgical goniolens
Fig. 4.8 Swan Jacob lens—pediatric surgical goniolens
Advantages of direct gonioscopy include: 1. A natural panoramic view 2. Erect image (useful for goniotomies) 3. No distortion of the angle structures 4. Good binocularity 5. Variation of the angle of visualization 6. Possibility of examining both eyes simultaneously.
The main disadvantages of this technique are: 1. It is a cumbersome and inconvenient technique 2. It requires the patient to be supine in a special room with special equipment, seldom available in a routine out patient departments 3. The angle can also be falsely closed if undue pressure is applied on the lens 4. The angle may appear artificially deep as the patient lies flat 5. It provides less magnification and poor detail 6. The hand held biomicroscope is difficult to use as it is heavy and not easy to manipulate. Due to these disadvantages, direct gonioscopy has largely been superseded by indirect gonioscopy and is only employed in congenital glaucoma surgery.
13
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Gonioscopy: A Text and atlas
■■Indirect Gonioscopy In this technique, light reflected from the chamber angle passes into the indirect gonioscope and is reflected by a mirror in the lens onto the examiner. These lenses are known as “gonioprisms” and may have 1, 2, 4 or even 6 internal mirrors with angles ranging from 59° to 64° to the horizontal. These lenses provide the clearest visualization of the angle structures with illumination and magnification provided by the slit lamp. The lenses may be modified with an antireflective coating when used for laser procedures. All examinations are performed at the slit lamp with the patient in sitting position. There are two types of indirect gonioscopes—the scleral type (Goldmann) lenses and the corneal type (Zeiss, Posner, Sussman) lenses (Figures 4.10–4.14 and Table 4.2). Another classification is based on the base curve of these lenses. Those with base curves flatter than the cornea do not require a coupling agent. The scleral-like lenses have a broad area of contact with the eye and a steep convex surface (steeper than the corneal curvature). A viscous substance with similar refractive index
as the cornea is therefore needed to fill the gap between the lens and the cornea. The use of the coupling substance can blur the patient’s vision and it is advisable that perimetry, ophthalmoscopy or fundus photography be performed prior to gonioscopy. A viscous methylcellulose fluid is used for filling up the concavity of the lens before application of the lens onto the globe. Because of a wide area of contact, these lenses cannot be used for indentation gonioscopy as they tend to press on the angle and close it. Inadvertent pressure on these lenses while viewing can compress the angle causing it to appear narrow and also cause blood to reflux into the Schlemn’s canal. To aid in visualization the lens may be tilted towards the area of interest or the patient asked to look towards the mirror, especially when viewing over a steep iris. Advantages of these scleral lenses are their excellent optics, ease of examination as the lens stabilizes the globe and permits examination even in an uncooperative patient as the lens keeps the globe stationary. There is very little corneal disruption when a non-preserved coupling solution is used. Features of various goniolenses available are given in Table 4.3 and 4.4
Fig. 4.10 Posner goniolens
Fig. 4.11 Sussman type goniolens
Direct and Indirect Gonioscopy
Fig. 4.12 Goldmann single and two mirror lenses
Fig. 4.13 Goldmann three mirror lens
Fig. 4.14 Goldmann six mirror lens
Table 4.2 Features of Indirect Goniolenses Type of the lens
Goldmann single mirror
Goldmann three mirror
Zeiss four mirror
Diameter of contact
12 mm
12 mm
9 mm
Overall diameter
15 mm
18 mm
9 mm
Size of rim
1.5 mm
3 mm
None
Mirror angulation
62°
59°
64°
Mirror height
17 mm
12 mm
12 mm
Distance from central cornea
3 mm
7 mm
5 mm
Radius of curvature
7.4 mm
7.4 mm
7.8 mm
Coupling fluid
Required
Required
Not required
Dynamic gonioscopy
Manipulation
Manipulation
Indentation
15
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Gonioscopy: A Text and atlas
The Goldmann single and double mirror lens is commonly used as it provides a good view of the superior and inferior angle. The Goldmann triple mirror lens has one mirror for gonioscopy (the smallest of the three) inclined at 590 while the single mirror has a 62° mirror. The overall diameter of a triple mirror lens is 18 mm. The diameter of corneal contact is similar, i.e. 12mm in all types of Goldmann lenses (Table 4.3 and 4.4). The main feature of these lenses is the posterior lens diameter of 12 mm and a posterior radius of curvature of 7.38 mm. The Ritch trabeculoplasty lenses have two 64 degree mirrors for superior angle viewing and two 59 degree mirrors for inferior angle viewing. One of the 59° and one of the 64° mirrors have a convex button in front that increases the magnification by 1.4x and concentrates the laser energy. The Trokel lens provides a wider field of view than the Goldman single mirror lens and a slightly better magnification (1.1x). It is designed for laser delivery to the angle. The corneal lenses, typified by the Zeiss lens have a 9 mm diameter corneal segment and a radius of curvature
of 7.72 mm which approximates that of most corneas. This allows the lenses to be used without a coupling fluid, using the tear film of the cornea. The corneal lenses permit a very rapid and comfortable examination to be made with rapid transfer from one eye to the other for comparison purposes. More importantly they do not interfere with subsequent fundus examinations. Air bubbles that accumulate under these lenses are easily removed by gentle rocking, rotation or reapplication. The small diameter of the lens minimizes lid contact. There is no suction adherence between the cornea and the goniolens. The view therefore is not very stable and subtle abnormalities may be missed unless the examiner has experience. The Zeiss lens comes with a detachable holding fork (the unger holder). The Posner lens has a handle attached to it and is made of plastic, while the Sussman lens is finger held (without a handle). All these lenses have four mirrors enabling a view of the entire angle without rotating the lens. The small areas between the mirrors may be viewed by turning the lens only by 11°. As the diameter of contact
Table 4.3 Features of Volk goniolenses Lens
Features
Image magnification
Field of view
Contact diameter
G-1 One-Mirror Glass Trabeculum Lens
Viewing and Treatment of the Anterior Chamber and Central Retina. All glass design provides superior clarity and durability compared to acrylic lenses. Highest magnification of any Gonio lens
1.5x
62°
15 mm
G-2 Two-Mirror Glass Trabeculum Lens
Viewing and Treatment of the Anterior Chamber and Central Retina. Two differently angled mirrors provide broader views of the anterior chamber. Highest magnification of any Goniolens
1.5x
60°/64°
15 mm
G-3 Three-Mirror Glass Gonio Fundus Lens
1.06x Viewing and Treatment of the Anterior Chamber and Central and Peripheral Fundus. Mirrors are accurately angled to eliminate gaps in the visualized fundus. High quality version of the commonly named Goldmann lens
60°/66°/76°
15 mm
G-4 Four-Mirror Glass Goniolens
Standard Goniolens for Static and Dynamic Gonioscopy. Four precisely angled mirrors provide full 360° views of the anterior chamber. All glass design provides superior clarity and durability compared to acrylic lenses
1x
4x64°
15 mm
G-4 Four-Mirror Glass High Mag
Standard Goniolens for Static and Dynamic Gonioscopy. Four precisely angled mirrors provide full 360° views of the anterior chamber. Crispest, clearest imaging with high magnification to appreciate details previously unattainable with Goniolenses.
1.5x
4x64°
15 mm
Three-Mirror Lens
Anterior Chamber and Central and Peripheral Fundus Diagnosis and Treatment
1.06x
60°/66°/76°
15 mm
1.0x
6x63°
8.4 mm
G-6 Six-Mirror Glass Goniolens
Direct and Indirect Gonioscopy
Table 4.4 Features of Ocular Goniolenses Lens
Description
Image magnification
Field of vision (static)
Lens height
Contact diameter
Ocular three mirror universal
Classic “Goldmann” type lens has three mirrors angled at 59°, 67° and 73° to permit viewing of the peripheral fundus and anterior chamber angle. 36° of the posterior pole can be viewed through the center of the lens
0.93x
140°
32 mm
18 mm
Ocular Karickhoff diagnostic
Four mirrors plus a central axis view give a complete view of the interior of the eye
0.93x
140°
32 mm
18 mm
Ocular magna view gonio
For gonioscopy and laser trabeculoplasty
1.3x
160°
23.5 mm
15 mm
Ocular single mirror gonio
Goniolens with one 62° mirror
0.8x
170°
19.5 mm
15 mm
Ocular two mirror gonio
Two opposing 62° mirrors provide a complete view of the anterior chamber angle with only a 180° lens rotation
0.8x
170°
19.5 mm
15 mm
Ocular three mirror 10 mm gonio
Three mirrors of 64°, 67° and 73° and a small diameter contact surface for use without methylcellulose
0.93x
140°
25 mm
10 mm
Ocular four mirror mini gonio
Four 62° mirrors allow complete observation 0.8x of the angle with little lens rotation. Small diameter flange is convenient for eyes with small palpebral fissures. Methyl cellulose not required for most patients
120°
22.5 mm
15 mm
Ocular Khaw 4D direct view gonio
Combines the most favorable features of traditional gonio prisms while providing a properly orientated view of the angle
0.8x
170°
24 mm
10 mm
Ocular Maxfield AC four mirror gonio
High Refractive Index glass provides total internal reflection even with fluid in contact with the mirrors
0.61x
90°+
22 mm
8.5 mm
Ocular Posner gonioprism
Four 64° mirrors with a handle. Small diameter contact surface allows static or dynamic gonioscopy without methylcellulose
0.8x
80°
13 mm
9 mm
Ocular Sussman four mirror hand held gonioprism
Four 64° mirrors for complete anterior chamber angle viewing with minimal lens rotation. No handle attached. Directly hand held for easy handling and stability. Small diameter contact surface allows static or dynamic gonioscopy without methylcellulose.
0.8x
80°
24.5 mm
9 mm
Ocular Thorpe four mirror gonioprism
Four 62° mirrors give a 360° view of the anterior chamber angle
0.8x
150°
32 mm
18 mm
Ocular Koeppe lens
Direct gonioscopy lens with magnification. The lens rests on the scleral flange creating a corneal vault and leaving the anterior chamber angle undisturbed
1.5x, 1.5x, 1.6x respectively for the three sizes large, medium and small
160°
19 mm, 18 mm, 17 mm
17
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Gonioscopy: A Text and atlas
is smaller than that of the cornea these lenses press on the center of the cornea and thus may be used for indentation gonioscopy. With indentation, the aqueous is pushed into the angle and opens it up allowing distinction between iridocorneal apposition and synechial angle closure. In contrast to the above mentioned lenses that use mirrors, the Allen Thorpe Gonioprism has four prisms and is held in place by its frame. This leaves both the hands of the examiner free. There are several advantages of indirect gonioscopy: 1. It can be performed on the slit lamp with minimum patient inconvenience 2. Gives excellent view utilizing slit lamp optics 3. The slit lamp beam creates an optical corneal wedge which is very useful in identifying the angle structures (discussed later)
4. It can be used to stereoscopically view the optic nerve head 5. Allows indentation or compression gonioscopy 6. Does not require special equipment and takes less time than direct gonioscopy 7. Especially useful for laser applications.
The drawbacks of this technique include: 1. False closure of the angle by pressure caused by scleral type lenses 2. Artifactual widening of the angle during use of the corneal type lenses 3. Inverted image, opposite angle is viewed 4. Inability to see both angles simultaneously 5. Use of viscous fluid with the Goldmann lenses which makes the cornea hazy 6. Can only be used with a slit lamp 7. Poor stereoscopic lateral view.
■■References 1. Fisch BM. Gonioscopy and the Glaucomas. Boston: Butterworth-Heineman, 1993.
3. Ritch R, Shields MB, Krupin T. The Glaucomas. St. Louis: C.V. Mosby Company, 1989.
2. Gorin G, Posner A. Slit Lamp Gonioscopy. Baltimore: Williams & Wilkins Company, 1967.
4. Shields MB. Textbook of Glaucoma Third edition. Baltimore: Williams & Wilkins Company, 1992.
Chapter 5
Slit Lamp Gonioscopy Techniques
The ophthalmologist should perform tonometry before the gonioscopic evaluation because pressure on the eye can artificially lower the intraocular pressure. A general examination should be performed on the slit lamp before inserting the gonioscope to view the cornea, iris, evidence of new vessels, inflammation, previous surgery or trauma. The physical positioning of patient and examiner during indirect gonioscopy is critical to avoid excessive body or head movement by the patient and to avoid fatigue-related hand tremor by the examiner.1 The table height of the slit-lamp must be adjusted so that the patient is seated comfortably with optimal chinrest and headrest support. The patients must be instructed to keep their forehead firmly against the head rest and not back away when the gonioscope is being inserted. The patient’s eye should be positioned in such a fashion to allow maximal vertical range of the slit lamp microscope via the joystick as this allows the superior and inferior angles to be viewed without having to adjust the chinrest during examination. The examiner should sit at a comfortable height for viewing and for supporting the elbow and hand holding the goniolens. An elbow rest must be used to avoid fatigue. Topical anesthesia and viscous fluid bottles must be kept ready before positioning the patient. Bottles of methylcellulose should be stored upside down to ensure that no air bubbles come out while pouring the solution on to the lens. The examiner must take a history of the medications being used by the patient as any drug causing mydriasis or miosis can influence the gonioscopic findings. The patient should never be dilated before doing gonioscopy.
■■GONIOSCOPY WITH SCLERAL LENSES (GOLDMANN) ■■Preparation • Patient is positioned at the slit lamp. The illumination is made coaxial and the magnification is kept low (x10). The patient’s lateral canthus is aligned with the canthal marker. A support for the elbow of the examiner is desirable. • It is preferable to dim the room lights as bright light can cause miosis and open up an ‘occludable angle’. 2 • Topical anesthetic is instilled in both the eyes (4% xylocaine or 0.5% proparacaine eye drops). • The lens surface is cleaned and disinfected. • The concave surface is filled with a viscoelastic gonioscopic solution or artificial tears. • Care should be taken to avoid air bubbles in the viscoelastic solution. This can be simply achieved by squeezing the
solution on a tissue first to express out any air bubbles and then transferring the stream onto the goniolens without releasing the pressure on the bottle.
■■Lens insertion (Figures 5.1–5.6) • The patient is asked to look up. The upper and lower lids are parted with the left hand while the right hand uses the rim of the gonioscope to push the lower lid down. • The gonioscope is then quickly rotated onto the eye. • Ask the patient to slowly look straight ahead. • The examiner now uses the left hand to stabilize the gonioscope while the right hand is free to control the slit lamp joystick. The thumb, index and middle fingers hold the lens, while the other two fingers stabilize the head of the patient. • Blood reflux into the Schlemm’s canal indicates excessive pressure.
■■Manipulation • This may be done with three finger technique (thumb and index and middle fingers) or two finger technique (thumb and index finger). • Hold lens between thumb and 2nd finger (first finger should be free). • Rotate lens by placing 1st finger on the front of lens and using finger and thumb to rotate lens (this method allows freedom of the other hand to manipulate the slit lamp thereby facilitating an efficient examination where the examiner need not leave the eyepieces).
Figure 5.1 Insertion of Goldmann Lens
20
GONIOSCOPY: A TEXT AND ATLAS
Figure 5.2 Lens apposed to lower lid margin
Figure 5.4 Goldmann Lens in place
Figure 5.3 Goldmann Lens rotated onto cornea
Figure 5.5 View of Gonioscope after being properly placed
• The remaining fingers may be rested on the patient’s cheek, the slit lamp headrest, or the vertical bar attached to the slit lamp headrest. Air bubbles that slip under the lens may be removed by tilting and turning the lens. • The wrist should be kept straight and forearm as vertical as possible. The elbow should be supported either by the table top of slit lamp or else on an elbow rest. This will prevent fatigue related tremor of muscles.
■■Viewing • Use vertical parallelopiped beam which is 2-3 mm wide. • The examiner must remember that he is viewing the opposite quadrant. • Examine first the inferior angle as it is the widest and most pigmented, which implies that the structures are easy to recognize.
Figure 5.6 Gonioscopy on the slit lamp biomicroscope
Slit Lamp Gonioscopy Techniques
• The mirror is rotated to inspect the other quadrants usually in 90 degree steps. • The slit beam is turned horizontal to view the nasal and temporal quadrants. • Examine each quadrant and note the findings. • Ask the patient to look towards the examining mirror for performing manipulative gonioscopy and viewing over a steep iris.
■■Lens removal • For removal the patient is asked to look nasally and squeeze his lids forcefully. • Pressure is applied to nudge the lens on the temporal side and introduce air. • Should this fail, the procedure may be repeated on the temporal side. • The lens may also be manipulated through a couple of rotations to loosen seal. If the lens is tightly stuck on the patient’s eye, gentle pressure on the globe with a finger can be used to facilitate lens removal. • It is important not to forcefully pull the lens away from the globe.
Figure 5.7 Insertion of Posner corneal Gonioscope
■■Irrigation • Rinse the superior and inferior cul-de-sacs with saline to prevent blurred vision or discomfort. • Topical antibiotic drop should be used after the procedure.
■■GONIOSCOPY WITH CORNEAL LENSES (POSNER/ZEISS)
Figure 5.8 Posner Lens being placed on the cornea
■■Preparation • Position patient at slit lamp with illumination coaxial with viewing system and at low magnification (x10). • Ensure appropriate alignment with lateral canthal marker to centre vertical range of slit lamp. • The lens surface is cleaned and disinfected. • No coupling fluid is required. • The lens surface may be lubricated with artificial tears. • Apply topical anesthesia.
■■Lens insertion (Figures 5.7–5.9)
Figure 5.9 Proper placement of Posner lens
• While patient looks straight ahead the lens is gently guided onto the corneal apex so that the edges do not indent the cornea. • The Zeiss type lenses should be applied with the eye in primary gaze and should touch the corneal surface sufficiently to create a fluid level without producing folds in Descemet’s membrane. • These lenses may be applied in either square or a diamond configuration. For the square configuration the flat
surfaces of the fork are grasped with the thumb on one side and the second and the third fingers on the other. The other two fingers rest on patient’s cheek and examiner’s palm faces the patient. The fork is oriented at a 45 degree angle to the eye. • In diamond configuration the fork is oriented horizontally and grasped between the thumb and second finger on the
21
22
GONIOSCOPY: A TEXT AND ATLAS
•
• • • •
•
top flat surface and third finger on the bottom flat surface. The back of examiner’s fingers rest on the patient’s cheek. The square configuration is preferable as it fits better in the palpebral aperture and if contact occurs between the lens and upper eye lid a flat surface is comfortable than a corner presented in diamond configuration. Furthermore the hand and forearm position used in the square configuration allows one to keep the wrist straight and the forearm vertical for better support and control. Use fingers to achieve stability by resting them on the patient’s cheek. The mirrors should be placed in the 12, 6, 3 and 9’O clock positions. Maintain minimal contact, to just eliminate air beneath the surface. If air bubbles accumulate during gonioscopy, they are easily eliminated by slight rocking, rotation, or removal and reapplication of the lens. Watch for folds in the Descemet's which indicate excessive pressure.
■■Manipulation • Manipulation is not as necessary as with Scleral-type lenses due to the four mirror configuration as only the slit lamp beam needs to be moved. • To view the area between the lenses the lens may be rotated slightly to either side by using the handle.
• The patient must be instructed to keep his eyes steady, otherwise a clear view is not obtained. • Minimal lens tilting can be used to visualize structures. Excessive tilt can obscure view. • Indentation (or compression) gonioscopy can be performed in eyes with primary angle closure glaucoma to differentiate an appositional from synechial angle closure.
■■Viewing • The procedure is similar to the Goldmann lens except that the lens is not rotated. • Viewing over a convex iris is more difficult as lens tilting puts the edge of the lens in contact with the cornea. This problem may be circumvented partially by indentation gonioscopy.
■■Lens removal • Simply release the gonioscope from eye as there is no suction adherence between the cornea and the goniolens.
■■Irrigation • No irrigation is required as the lens does not blur vision on removal and no coupling viscoelastic is used.
■■REFERENCES 1. Thomas R, Thomas S, Chandrashekar G. Gonioscopy. Indian J Ophthalmol. 1998;46(4):255–61.
2. Cockburn DM. Indications for gonioscopy and assessment of gonioscopic signs in optometric practice. Am J Optom Physiol Opt. 1981;58(9):706–17.
Chapter 6
Special Gonioscopy Techniques
The anterior chamber angle width should be initially evaluated in primary gaze with all types of goniolenses positioned centrally on the cornea.3,4 With the scleral type lenses care is to be taken to avoid indentation of the peripheral cornea, as this can narrow the angle. Manipulation is of value in studying angle anatomy in narrow iridocorneal angles. A more tangential viewing of
the angle aids in identification of angle structures obscured by a convex iris. This can be achieved in Goldmann type lenses by simply asking the patient to look in the direction of the mirror or moving the mirror towards the angle being viewed (Figures 6.1–6.8). The former technique gives a better view of the narrow angles than the procedure of moving the goniolens along the corneal surface towards the angle to be viewed. When the patient’s eye is rotated, the light path from the mirror to the examiner remains perpendicular to lens surface, whereas when the lens is tilted, the light path is no longer perpendicular but suffers an astigmatic distortion. Such distortion is specifically a problem in laser trabeculoplasty because it transforms the laser spot into a streak. Although having the patient look in the direction of the mirror has an advantage of viewing deep into the angle recess – “dive bomber view”, it has the disadvantage of more tangential, foreshortening its image and degrading the image quality. When the iris is flat one can instead have the patient to look away from the direction of mirror and thereby obtain a view parallel to the iris and nearly perpendicular to the meshwork- “cruise missile view” which will yield an optimal image quality. Once angle structures are seen, the slit beam may be narrowed to identify the corneal wedge and interpret the findings. A narrow short slit beam off—axis should be used for the following reasons: 1. To ensure that the point of contact of the iris with the eye wall is being seen and one can judge an over the hill
Figure 6.1 A steep iris does not allow view of the angle recess
Figure 6.2 Manipulation of Gonioscope towards angle being viewed
On routine gonioscopy, the angle structures may not be identified in eyes with a steep iris configuration and a narrow angle. A steep approach to the angle makes examination difficult in such cases and the examiner has to use special maneuvers to look over the iris. This technique of manipulating the goniolens to visualize over a steep iris (over the hill view) is known as dynamic or manipulative gonioscopy. The second technique of indentation gonioscopy involves the use of a Zeiss type corneal indirect gonioscope to indent the cornea and thereby open up the angle, in order to differentiate between appositional or synechial closure.1 A new technique for objective estimation of the angle has also been developed, which uses a reticule mounted on the slit lamp oculars to measure the distance between the iris insertion and the Schwalbe’s line.2 This technique is known as Biometric Gonioscopy. Another method is by using the technique of sclerotic scatter on slit lamp biomicroscopy. The angle structures can sometimes be seen and identified more accurately than with direct illumination.
■■Manipulative Gonioscopy
24
Gonioscopy: A Text and atlas
Figure 6.3A Narrow angle recess on normal view
Figure 6.3B Opening up of angle recess on manipulation
Figure 6.4A Closed angle in primary position
Figure 6.4B Angle opening on manipulation
Fig 6.5 Angle opening on manipulation
Special Gonioscopy Techniques
Fig 6.6 Angle opening on manipulation
Fig 6.7 Angle opening on manipulation: appositional closure
Fig 6.8 Angle not opening on manipulation: synechial closure
25
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Gonioscopy: A Text and atlas
appearance by noting that the slit beam on the iris will not intercept the corneoscleral beam but will end to the side of it. 2. To employ the paralleopiped method. 3. To prevent the light from passing through the pupil. The examiner should report the normal angle view in primary gaze and then document the opening of the angle on manipulation by asking the patient to look into the mirror of the gonioscope, opposite to the angle being examined. For example if you are examining the inferior angle with a Goldmann single mirror gonioscope, the mirror is positioned superiorly. After viewing the angle in primary gaze, you now ask the patient to look upwards, i.e. towards the mirror. This allows a better view of the inferior angle as the examiner can look over the iris and into the angle. If the patient looks in the direction opposite to the mirror, the angle appears narrower and vice versa. This manipulative maneuver can be facilitated by shifting the fixation light, which is positioned in front of the other eye, in the same direction, as that of the gonio mirror being viewed. The examiner can produce a similar effect by moving the lens towards the part of the angle to be examined (e.g. by displacing a goniolens inferiorly when examining the inferior quadrant).
■■Indentation Gonioscopy With the corneal type goniolenses, that have a small diameter, the central cornea may be indented to force the aqueous out and artificially widen the angle. Because the
Fig. 6.9 Opening of angle recess on pressure gonioscopy
smaller radius of curvature allows these lenses to come into direct contact with the anterior corneal surface, central depression of the cornea will displace aqueous humor peripherally and the iris root posteriorly (Figures 6.9–6.12). This technique is also known as pressure or dynamic gonioscopy. When the iridocorneal angle is optically narrow, indentation gonioscopy facilitates the identification of angle structures. Should the angle be closed, indentation helps differentiate appositional from synechial angle closure. This is important as synechial closure is irreversible, while appositional closure can be reversed. The mechanism by which corneal indentation deepens the peripheral angle is not as supposed by just the reversal of the pressure gradient from the posterior chamber to the anterior chamber, though it generally occurs. Corneal indentation still deepens the angle when a large sector iridectomy is present and no pressure gradient is possible. Rather the increased pressure from corneal indentation causes the stretching of limbal ring of sclera resulting in a partial straightening of the corneoscleral angle and posterior rotation of the attached iris and ciliary body. Indenting the central cornea however causes folds in the central cornea, which can distort the angle details. The angle structures may be identified by using a narrow slit beam and applying and withdrawing pressure in repeated sequence. Also sliding the lens towards the angle reduces the folds and improves view. Extreme gaze in the direction of the mirror and lifting of the goniolens while pressing inward can aid maximal displacement of the aqueous peripherally when angle structures are not readily apparent despite indentation. Indentation is not possible with the Goldmann type gonioscopes as they have a diameter greater than the corneal diameter and tend to narrow the angle on pressure. Indentation is difficult when the intraocular pressure is higher than 40 mmHg. Corneal indentation is also useful to look for iridodialysis and cyclodialysis in a patient with shallow anterior chamber from hypotony related to trauma.
Figure 6.10 Indentation Gonioscopy being performed with Posner Lens
Special Gonioscopy Techniques
Before indentation
After indentation
Figure 6.11 Indentation/Pressure Gonioscopy pushes aqueous into angle and opens up the angle recess
displaced ciliary body and iris root, typically seen in plateau iris. c. The angle widens but iris strands remain attached to the outer wall of the angle. This represents organic synechial closure of the angle. d. The iris moves only slightly and evenly backward, but retains a convex profile. This can occur due to an anteriorly displaced lens or a large diameter lens.
■■Biometric Gonioscopy
Figure 6.12 Indentation gonioscopy
When no angle structure is directly visible before indentation, the closure of the angle can be due to three reasons:5, 6, 7, 8 1. Synechial 2. Appositional 3. Optical (apparent closure of the angle due to steep curvature of the peripheral iris, impairing visibility of angle structures) When no angle structure is directly visible before indentation, four things can happen on indentation (Figure 6.13): a. The iris moves peripherally backwards, assumes a concave configuration and the angle recess widens. This represents an appositional closure with a suspicion of a relative pupillary block. b. The iris moves peripherally backwards, but the periphery of the iris bulges out and does not assume a concave configuration. This represents an anteriorly
This is a new method for objective measurement of the anterior chamber angle proposed by Congdon et al. (Ophthalmology 1999;106:2161–7).2 In this method gonioscopic measurements are performed with the help of a special reticule. The anterior chamber angle is viewed under the following conditions on a Haag-Stret 900 BM slit lamp: ambient lighting from a small side lamp is used to provide only an indirect illumination with a total magnification of x16, power of 6 W, middle filter setting and a slit lamp beam of 4 mm length and 1mm width. The reticule is mounted on a slit lamp 10x ocular and ruled in 0.1 mm units, which is used to measure the distance between the insertion of the iris and the Schwalbe’s line. Measurements are recorded separately in the superior, inferior, nasal and temporal quadrants. If the angle is closed a measurement of 0 is recorded while an occludable angle is defined as one with an average measurement of 0.25 mm or less for the four quadrants. This method correlates well with other measures of the anterior chamber angle like conventional gonioscopy and Scheimpflug photography, shows a much higher degree of interobserver reliability than conventional gonioscopy and can be readily learned and performed by an inexperienced observer. Hence it offers a definite advantage over conventional gonioscopy which is purely a subjective technique and has a long learning curve.
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Gonioscopy: A Text and atlas
Figure 6.13A Indentation gonioscopy in an apparently closed angle
Figure 6.13B If the angle opens up, it was a case with appositional closure
Figure 6.13C Indentation reveals synechial Irido corneal adhesions (PAS)
Figure 6.13D A thick lens does not allow the chamber to deepen or the iris to move backwards
■■REFERENCES 1. Bruno CA, Alward WL. Gonioscopy in primary angle closure glaucoma. Semin Ophthalmol. 2002;17(2):59–68. 2. Congdon NG, Spaeth GL, Augsburger J, Klancnik J Jr, Patel K, Hunter DG. A proposed simple method for measurement in the anterior chamber angle: biometric gonioscopy. Ophthalmology. 1999;106(11):2161–7.
5. Cockburn DM. A new method for gonioscopic grading of the anterior chamber angle. Am J Optom Physiol Opt. 1980;57(4):258–61. 6. Terry JE. Gonioscopy: evaluation and interpretation. J Am Optom Assoc. 1977;48(11):1415–23.
3. Thomas R, Thomas S, Chandrashekar G. Gonioscopy. Indian J Ophthalmol. 1998;46(4):255–61.
7. Prokopich CL, Flanagan JG. Gonioscopy: evaluation of the anterior chamber angle. Part I. Ophthalmic Physiol Opt. 1996;16 Suppl 2:S39–42.
4. Cockburn DM. Indications for gonioscopy and assessment of gonioscopic signs in optometric practice. Am J Optom Physiol Opt. 1981;58(9):706–17.
6. Prokopich CL, Flanagan JG. Gonioscopy: evaluation of the anterior chamber angle. Part II. Ophthalmic Physiol Opt. 1997;17 Suppl 1:S9–13.
Chapter 7
Normal Gonioscopic Anatomy
In performing gonioscopy the most important part of learning is the recognition of the normal angle structures. The purpose of gonioscopy is to determine the topography of the anterior chamber angle based on recognition of angle landmarks. The following features must be determined when viewing an angle during gonioscopy:1 1. Angle structures visible in primary gaze and on manipulation or indentation as required 2. Level of iris insertion 3. Shape of peripheral iris profile 4. Width of the angle recess 5. Degree of trabecular pigmentation 6. Areas of iridotrabecular apposition 7. Areas of iridocorneal synechiae. One should first view the angle structures in the inferior quadrant because of its greater depth and its increased pigmentation compared with the other quadrants, which makes identification of landmarks much easier. After examination of the inferior quadrant, the remaining quadrants can be viewed sequentially in a clockwise direction. Special precaution must be taken to use dim illumination when projecting the slit beam into the angle and to keep the beam length small such that it does not cross the pupil. Bright illumination and a long beam will artifactually open up the angle recess and deepen the anterior chamber by inducing pupillary constriction. 2 The angle width should be determined in primary position first. The best examination is in direct focal illumination. A narrow beam is used initially for precise examination and localization, and a wide one for diffuse illumination and gross viewing. Retroillumination and proximal sclerotic scatter may be needed occasionally for internal viewing and identification of the scleral spur. A fixation light may be used to maintain optimal ocular alignment. Starting from the root of the iris the following structures are present in a normal adult angle:3 1. Ciliary body band 2. Scleral Spur 3. Schlemm’s canal 4. Pigmented Trabecular meshwork 5. Non-Pigmented Trabecular meshwork 6. Schwalbe’s line. For identification of the angle, the scleral spur and the Schwalbe’s line are the most consistent landmarks. The scleral spur is a thin, pale stripe between the ciliary face and the pigmented zone of the trabecular meshwork. The examiner first starts by identifying the exact position of
the Schwalbe’s line using the parallelopiped or the corneal wedge technique.
■■The corneal wedge-localizing the Schwalbe’s line Identifying the corneal wedge is the key step in defining the angle structures. By using a thin slit of light inclined 10–15° from the angle of the oculars and sharp focus, projected onto the iridocorneal angle, 2 light reflections are noted, one from the external surface of the cornea and its junction from the sclera and the other from the internal surface of the cornea. These two reflections meet at Schwalbe’s line (Figures 7.1–7.3). At this landmark the external and internal reflections of the three-dimensional parallelepiped of light merge into a two-dimensional single line with a brighter luminance, which extends in a perpendicular direction across the trabecular meshwork. This marks the anterior border of the trabecular meshwork. This method is of great value in lightly pigmented angles and in angles where there is difficulty in identification of normal landmarks or if there is pigment deposition anterior to the Schwalbe’s line (Figure 7.4). However, identifying the corneal wedge may be difficult in some cases. By gently sliding the gonioscopy lens in the direction of the mirror being used, the examiner gains
Figure 7.1 Apex of the corneal wedge marks the Schwalbe’s line
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Gonioscopy: A Text and atlas
Figure 7.2 Apex of the corneal wedge is not visible in a closed angle
Figure 7.3 Apex of corneal wedge in an open angle
a better view of the cornea and the corneal wedge. Locating the wedge is easiest in the superior and inferior angles as it is easy to generate a vertical slit. Once the wedge is identified and the angle graded in the superior and inferior quadrants, studying the nasal and temporal with broad illumination is sufficient.
■■Iris A normal iris has radial markings with crypts. These crypts if deep may prevent angle closure and acute elevations of IOP as pointed out by Posner. These features may be obscured if there has been an attack of anterior uveitis giving a flat featureless appearance. An asymmetric appearance with unilateral involvement may be noted in Fuch’s
Figure 7.4 Pigmentation of the angle anterior to apex of the corneal wedge (may be confused as the trabecular meshwork)
heterochromic iridocyclitis. The iris also has concentric contraction rolls. These become more prominent when the pupil is dilated. The root of the iris is delimited anteriorly by the roll of Fuchs which may play a part in the closure of the angle in narrow angle eyes. The most peripheral roll is often more prominent especially in plateau iris syndrome and may even obscure view of the angle. The iris becomes thinner and smoother as one proceeds to the angle. A scalloped border may be present where the iris inserts into the face of the ciliary body. It is important that the examiner notes the presence of nevi, tumors, atrophy, iridodonesis and abnormal pigmentation. Abnormal convexity of the iris occurs in pupillary block, thick lenses and with tumors or cysts of the iris pigment epithelium or the ciliary body. The 3 major iris features that must be examined include: 1. Contour of the iris (concave, convex, flat—Figures 7.5 and 7.6). 2. Site of iris insertion (Figure 7.7) 3. Angulation between the iris insertion and slope of the inner cornea The peripheral iris configuration may provide important clues to the presence of pigment dispersion syndrome, plateau iris, or pupillary block. In relative pupillary block, the convex iris indents smoothly. In plateau iris the iris assumes a sine wave configuration, with iris indenting maximum at the lens equator and then elevating peripherally over the anteriorly located ciliary processes. The root of iris is the only structure of the angle that is subject to positional changes. Therefore the anatomic insertion of the iris root has an important bearing on the configuration of the angle. The root of the iris offers less resistance to pressure in posterior chamber and it may be shorter and thicker than normal in certain individuals and thus cause narrow angle recess.
■■Iris Processes Iris processes are present in one-third of normal eyes, are more frequent in brown eyes and are not indicative of any
Normal Gonioscopic Anatomy
Figure 7.5 Convex Iris Configuration
Figure 7.6 Concave Iris Configuration
Table 7.1 Features of PAS distinguishing them from iris processes
1. Typically broader than iris processes 2. Irregular 3. Tent-shaped 4. Bridge the angle recess instead of following it 5. Do not follow the concavity of the angle recess 6. Conceal/obscure underlying angle landmarks 7. Inhibit posterior movement of the iris with indentation gonioscopy 8. Drag normal radial iris vessels with them
Figure 7.7 anterior iris insertion with iris processes
disease process. They are typically gray or brown lacy, fingerlike extensions of the peripheral iris which follow the angle concavity (wrap around the angle recess) to insert into the scleral spur or posterior portion of the trabecular meshwork (Figures 7.8–7.11). Sometimes they line the inner, deep portion of the angle recess. They are frequently seen in the nasal quadrant and are mild in density, never interfering in aqueous flow. They follow the concavity of the angle recess and the iris, do not block the iris movements during indentation gonioscopy and on high magnification one may see a contraction of the processes on exposure to a light stimulus. With traumatic angle recession, the iris processes may be broken, a subtle sign of recession. R Kimura and R Z Levene had graded the iris processes into minimum, moderate and marked number of process to ciliary body, trabecular meshwork and Schwalbe’s line. Their importance lies in the fact that they are often confused with peripheral anterior synechiae (PAS). PAS have the following features which can distinguish them from iris processes (Table 7.1):
9. Associated with anterior pigmentation as a consequence of iris apposition in angle closure or pigment deposition in uveitis
■■Ciliary body band This is the portion of ciliary body, which is visualized in the anterior chamber. The iris inserts into the concave face of the ciliary body leaving some portion of the cilary body visible anterior to the iris. The width of the band depends on the level of iris insertion and tends to be wider in myopic eyes and narrow in hypermetropia. The color of the band is usually grey or dark brown. The width of the band must be compared between the two eyes before commenting on any abnormality associated with a concussion injury (e.g. angle recession).
■■Scleral Spur This is the posterior lip of scleral sulcus which is seen as white line between the ciliary body band and the trabecular meshwork (Figures 7.12–7.16). The spur is a ridge of scleral tissue anterior to the ciliary body band that marks the
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Gonioscopy: A Text and atlas
Figure 7.8 Iris processes
Figure 7.9 Iris processes
Figure 7.10 Iris processes
Figure 7.11 Iris processes
Figure 7.12 The normal anterior chamber angle
Figure 7.13 Open angle on gonioscopy: low magnification
Normal Gonioscopic Anatomy
Figure 7.14 Open angle on gonioscopy: high magnification
Figure 7.15 Open angle on gonioscopy in high myopia
■■Trabecular Meshwork
Figure 7.16 Schwalbe’s line (SL), Trabecular meshwork (TM) , white band of scleral spur (SS) and ciliary body band (CBB) visible in the angle
posterior border of the trabecular meshwork. In some cases it may be obscured by a dense uveal meshwork, an anterior iris insertion, iris processes, peripheral anterior synechiae or excessive pigmentation. The scleral spur is usually white to light gray in color. Unless one sees the scleral spur one is not sure that the full extent of trabecular meshwork is seen. This is important because the filtering posterior one-third of trabecular meshwork and the Schlemm’s canal lie just anterior to the spur. The spur is the point of insertion for most of the longitudinal muscle fibers of the ciliary body, whose action alters the facility of aqueous flow and the corneoscleral trabecular sheets.
The trabecular meshwork extends posteriorly from the Schwalbe’s line to the scleral spur. It has a ground-glass appearance. The meshwork is non-pigmented and smooth in infants gradually accumulating more and more pigment with age. As most of aqueous flow occurs through the posterior part, this is the part that is pigmented, the anterior part remaining non-pigmented. The pigmentation is usually heaviest inferiorly due to gravitational settling and aqueous circulation. Most individuals over the age of 50 years have pigmentation in the inferior angle and the amount of pigmentation has little relation to skin/hair color. If pigment is significant, especially if superior GREATER than inferior quadrants, suspect: a. Exfoliation syndrome b. Pigment dispersion syndrome c. Previous inflammation Gonioscopically, the trabecular meshwork has an irregular roughened surface, which in childhood appears as a glistening, translucent like semi-transparent gelatin with a stippled surface due to large openings of the uveal meshwork. The transparency decreases with age. The width of the band is 0.5 mm but when observed through the 10x magnification of slit lamp it appears as 5 mm wide. The examiner’s view should parallel the iris when looking at the trabecular surface.
■■Schlemm’s canal Schlemm’s canal is not visible in most individuals. It lies deep within the posterior trabecular meshwork and anterior to the scleral spur. Blood in the Schlemm’s canal causes it to be visible. It is seen as a red streak in the posterior half of the trabecular band sometimes continuous or more often
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Gonioscopy: A Text and atlas
discontinuous because of bands bridging the canal or adhesions between internal and external walls of the canal. This may happen when a scleral goniolens is pressed too hard on the eye causing the blood to regurgitate into the canal. Blood also appears when the episcleral venous pressure is high as in a carotico-cavernous fistula, in Sturge–Weber syndrome, venous compression, ocular hypotony, sickle cell disease or occasionally in normal eyes due to suction from the goniolens.
■■Schwalbe’s Line
the location of the pigmented trabecular meshwork. In contrast to the trabecular meshwork the pigmentation in a Sampaolesi’s line is often spattered in a discontinuous fashion resembling salt and pepper and is usually confined to the inferior quadrant. Pigments may be present near the Schwalbe’s line as well (Figure 7.20). The examiner must again use the corneal wedge to prevent any confusion in identification of the angle structures.
■■Normal blood vessels
The Schwalbe’s line marks the transition between the endothelium of the cornea and the trabecular meshwork. It represents the anterior border of the trabecular meshwork and is the termination of the Descemet’s membrane. At this junction, the corneal radius of curvature changes to the larger radius of the sclera. This change in curvature and the beginning of roughness of the trabecular surface provide an ideal lodging place for pigment granules that may be carried into the inferior angle by aqueous currents. The Schwalbe’s line is a collagen condensation of the Descemet’s membrane between the trabecular meshwork and the corneal endothelium and appears as a thin translucent line. A slight change in color and density from the trabecular meshwork to the cornea marks the line. Often it is too faint and only the corneal wedge facilitates its identification. In most eyes it is a flat transition zone between the trabecular and corneal endothelium, while in some eyes it is a ridge like structure. A prominent Schwalbe’s line constitutes the posterior embryotoxon, which may be a normal variant or be associated with the Axenfield-Rieger syndrome (Figures 7.17–7.19). Pigmentation anterior to the Schwalbe’s line constitutes the Sampaolesi’s line and is a non-specific finding in heavily pigmented angles, both physiologic and pathologic. This extra line of pigment can cause confusion in determining
In the normal anterior chamber angle, blood vessels may be visible in 50% to 60% of blue eyes and in 10% to 16% of brown eyes. Three distinctly different types of vessels may be seen—circular ciliary body band (also called circular iris root), radial iris root, and radial ciliary body band. The circular ciliary body band vessels are the ones most commonly seen. They tend to take a sinous course in the angle recess. The radial iris vessels emanate from the major arterial circle, appear at the iris root, hook over the last iris roll and disappear into the iris stroma. The radial ciliary body band vessels appear as thin, linear red streaks which lie deep within the ciliary body and course perpendicular to the iris plane. The origin of these vessels remains uncertain. The normal blood vessels in contrast to the neovascularization of the angle are typically broad, appear in short segments, do not extend anterior to the scleral spur, and do not arborize in the trabecular meshwork. Pathological vessels in the angle tend to be fine, they cross the scleral spur, may branch and follow no pattern (Figure 7.21). Fibrous tissue is often present along the new vessels though this is seldom appreciated clinically. Neovascularization of the angle in the absence of iris neovascularization may sometimes be noted in diabetic patients. Hence gonioscopic examination of the angle should be routinely done in all diabetics.
Figure 7.17 Prominent Schwalbe’s line
Figure 7.18 Prominent Schwalbe’s line
Normal Gonioscopic Anatomy
Figure 7.19 Prominent Schwalbe’s line
Figure 7.20 Anteriorly placed Schwalbe’s line
Figure 7.21 Neovascularization of angle in a case of proliferative diabetic retinopathy
Figure 7.22 Ciliary processes visible in a case of aniridia
Blood vessels are normally not seen on routine gonioscopy until one actually looks for them in the angle although loops from the major arterial arcade may appear in front of ciliary body and less commonly over scleral spur and trabecular meshwork. These vessels typically take circumferential route in the angle with very few anastamoses. Any blood vessel crossing the scleral spur should be considered as abnormal.
■■Determination of Angle Width
■■Other Regions The ciliary body, the ciliary processes, the zonules and the edge of the lens may be visible through the gonioscope in an eye which is widely dilated, or one with a complete iridectomy or an aniridic eye (Figure 7.22). The posterior corneal surface may also be seen with the gonioscope to identify pathologic findings like pigment deposition, keratic precipitates, or endothelial changes.
The width of the angle is determined by 1. The site of insertion of the iris on ciliary body face 2. Convexity of the iris 3. Prominence of the peripheral iris roll 4. Pupillary size. The angle width is of prime importance in establishing the risk for angle closure. The main aims of assessing the angle width are: 1. Evaluation of functional status of the angle 2. Degree of angle closure 3. Risk of future closure Gonioscopy provides a subjective assessment of the angle width which can be obtained as the angle between two imaginary tangential lines drawn to the inner surface of
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Gonioscopy: A Text and atlas
the trabeculum and the anterior surface of the iris about one third distance from its periphery. An indirect way of estimating the depth is by documenting the most posterior structure seen. The posterior the angle structure visible, wider is the angle.
■■Recording A. Angles i. Use X diagram ii. Record the most posterior structure seen—CBB, SS, TM, SL or none iii. Record the effect on manipulation iv. Mention the iris configuration, recess and insertion. B. Interpretation of angles i. If less than 1/2 of the TM is visible, the patient is at risk for angle closure ii. If CBB is seen, the angle is wide open iii. If no structures are visible, the angle is closed C. Pigmentation—Grade 0 to 4 4: dense 3: moderate 2: light 1: trace 0: none Estimate an average if pigmentation is in sections D. Record presence of iris processes in the appropriate quadrant E. Record any anomalies in the appropriate quadrant
■■Difficulties and Artifacts in Gonioscopy An error during the performance of gonioscopy most often results from lack of training on the part of the observer
or misinterpretation of poorly visualized structures. The following points should be kept in mind while doing gonioiscopy: 1. A slightly different view of the angle topography is achieved when the same eye is examined with a different lens. 2. Angles may look wider with the Koeppe lens. 3. The scleral lip of the Koeppe and Goldmann lenses can press on the outer sclera and indent it towards the iris, narrowing the angle. 4. Pressure by the Zeiss lens on the central cornea can artificially widen the angle. 5. Pressure with the Zeiss lens can produce folds in the Descemet’s membrane and obscure angle view. 6. Tiny air bubbles may adhere to oil secretions on the gonioscopic surface and impede the normal view. They require removal with soap and water. 7. Residues of methylcellulose can dry and adhere to the surface of the gonioscope, clouding the gonioscopic view. All lenses must be cleaned after use. 8. Pigment anterior to the Schwalbe’s line may be mistaken for the trabecular meshwork and the angle reported as narrow. 9. With the Koeppe lens, the patient’s nose sometimes prevents adequate visualization of the upper temporal angle. In such cases, a view of the angle can be obtained by asking the patient to look up and temporally. 10. An edematous corneal epithelium due to raised IOP does not permit visualization of the angle. The IOP should be reduced and the edema cleared by the use of topical anhydrous glycerol drops.
■■References 1. Shields MB. Textbook of Glaucoma Third edition. Baltimore: Williams & Wilkins Company, 1992. 2. Kanski JJ, McAllister JA Glaucoma: A Color Manual of Diagnosis and Treatment. Oxford: Butterworth-Heineman, 1989.
3. Fisch BM. Gonioscopy and the Glaucomas. Boston: Butterworth-Heineman, 1993.
Chapter 8
Gonioscopy Grading Systems
Grading of the angle is essential to allow for a systematic approach in the evaluation of angle anatomy. Grading allows a classification of different patients, facilitates comparison of findings at different times in the same patient, is vital for recording the gonioscopic findings and their communication and interpretation by other ophthalmologists. Many grading systems are available to describe the angle, all of which give a standardized description of angle structures and abbreviate that description. A quadrant-by-quadrant or clock hour description of the angle, noting localized findings such as neovascular tufts, angle recession, or peripheral anterior synechiae (PAS) is also helpful and descriptive and may also be used to document serial gonioscopic findings. The examiner must specify which grading system he has used to allow for future comparisons. The following grading systems are currently in wide use and should be familiar to the examiner. It is helpful to put up charts of these systems in the outpatient department as it is difficult to memorize these alphanumeric systems. If you are not comfortable with using these systems, just record the most posterior angle structure seen and comment on iris configuration and angle pigmentation. Four angle grading systems in use are: 1. Shaffer 2. Spaeth 3. Scheie 4. RPC Classification (Dr Rajendra Prasad Centre for Ophthalmic Sciences)
■■Shaffer’s system The Shaffer’s system describes the angle between the iris and the trabecular meshwork (Table 1).1 Angles > 20° are considered to be wide open and incapable of closure. The angle is not actually measured in degree, it is only a rough estimation of the angle width (Figure 8.1). The Spaeth system grades three aspects of angle anatomy:2 1. Level of iris insertion (Figure 8.2). 2. Angular width of angle recess (Figure 8.3). 3. Iris configuration (Figure 8.4).
Figure 8.1 Shaffer grading of the angle width Table 8.1 Shaffer system Grade Number
Angle width
Comments
4
35-45°
Wide open – closure impossible
3
20-35°
Wide open – closure impossible
2
20°
Narrow – closure possible
1
≤10°
Extremely narrow – closure probable
Slit
Slit
Narrowed to slit – closure probable
0
0°
Closed
Insertion of Iris Root a. (Anterior): Iris inserts anterior to the Schwalbe’s line b. (Behind Schwalbe’s line): anterior to posterior limit of trabecular meshwork c. (Centered on Sclera): On the scleral spur d. (Deep to Scleral spur): Behind the scleral spur e. (Extremely deep): On the ciliary band
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Gonioscopy: A Text and atlas
Configuration of the Peripheral Iris s = steep, anteriorly convex r = regular or flat q = queer, anteriorly concave
Figure 8.2 Spaeth grading of site of iris insertion
The Spaeth system also labels the degree of trabecular meshwork pigmentation (TMP) from 1 (minimal) to 4 (dense). If indentation demonstrates the iris insertion to be “C”, when it originally appeared to be “B”, then it should be written as (B) C. In this system the angle may be documented as (B) C 30 r / 2 + TMP. B indicates visible iris insertion, C indicates the same after indentation, 30 indicates the width of the angle in degrees, while “r” stands for a regular or flat iris configuration and mild trabecular meshwork pigmentation.
■■Scheie System
Figure 8.3 Spaeth grading of angle width
Scheie developed a grading system (Table 8.2) that used Roman numerals to describe the degree of angle closure with larger numbers signifying a narrower angle.3 This system also describes angle pigmentation on a scale from 0 (no pigmentation) to IV (heavy pigmentation).
■■RPC classification This is the classification routinely used at our institute for grading the angle with the patient in primary position. Grade 3 or less is considered as a narrow angle. Grade 0 Closed, no dipping of the slit lamp beam Grade 1 Dipping of the beam Grade 2 Schwalbe’s line and anterior third of trabecular meshwork seen Grade 3 Posterior 2/3 of trabecular meshwork is seen Grade 4 Scleral spur is seen Grade 5 Ciliary body band is seen Grade 6 Last roll of iris seen Figure 8.4 Spaeth grading of peripheral iris curvature
■■Angular width of angle recess The estimated angle formed between a line tangential to the trabecular meshwork and a line tangential to the iris surface about one third of the way from the periphery is the angular width of angle recess. Angular width Slit 10° Narrow 20° 30° Wide 40°
Table 8.2 Scheie system Grade
Structures visible
Comments
Grade 0 Ciliary body band (wide open)
No angle closure
Grade I
Ciliary body band narrow
No angle closure
Grade II
Ciliary body band not Closure very unlikely seen. Scleral spur seen
Grade III
Posterior trabecular meshwork not seen
Closure likely
Grade IV
Gonioscopically closed
Closed angle
Gonioscopy Grading Systems
■■Diagrammatic representation of angle anatomy
The angle is written as:
This basically represents the superior and inferior angle and the most posterior structure seen (3 = posterior trabecular meshwork visible in superior angle, 4 = scleral spur visible in inferior angle). The arrow 3 → 5 indicates the actual angle structure visible in primary gaze (in this case the trabecular meshwork = 3) and the structure which becomes visible after doing manipulative gonioscopy (in this case the ciliary body band = 5). This system can also be modified such that it just states the angle structure visible without assigning a numerical number, which is easy to remember.
A diagram (Figure 8.5) may be used to represent the gonioscopy findings using two concentric circles to represent the Scleral spur and the Schwalbe’s line. Any abnormality is drawn at the appropriate clock hour. The following table shows a comparison of the different grading systems (Table 8.3).
Figure 8.5 Diagrammatic representation of gonioscopic findings Table 8.3 Comparison of different Grading systems Angle recess
Scheie
Shaffer
Spaeth
RPC
0
Grade IV
Grade 0
Grade A
Grade 0 – 1
0–10
Grade III
Grade 1
Grade B
Grade 1- 2
10–20
Grade II
Grade 2
Grade C
Grade 3
20–30
Grade I
Grade 3
Grade D
Grade 4
30–40
Grade 0
Grade 4
Grade E
Grade 5 – 6
■■References 1. Shaffer RN, Tour RL. A comparative study of gonioscopic methods. Am J Ophthalmol 1956;41:256–265. 2. Spaeth GL. The normal development of the human anterior chamber angle: a new system of descriptive grading. Trans Ophthalmol Soc UK 1971;XCI:709.
3. Scheie HG. Width and pigmentation of the angle of the anterior chamber. A system of grading by gonioscopy. Arch Ophthalmol 1957;58:510.
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Chapter 9
Assessment of Angle Pathology – An Overview
Assessment of abnormalities in the angle structures is the main utility of doing gonioscopy in clinical practice. In addition to anatomical angle width and configuration which is important in the pathogenesis of primary angle closure glaucoma, various pathologies may first be visible in the anterior chamber angle. The following abnormalities may be detected while performing gonioscopic examination: Abnormalities which may be detected on gonioscopy: 1. Anterior insertion of iris 2. Pigment—type, location, amount 3. Iris processes 4. Iridotrabecular or iridocorneal adhesions 5. Bleeding spots 6. Blood in Schlemm’s canal 7. Congenital variation 8. Cyclodialysis 9. Angle recession 10. Iridodialysis 11. Exfoliative material 12. Foreign body 13. Hyphema 14. Hypopyon 15. Imperforate membrane 16. Tumor 17. Cysts 18. Vitreous strands 19. New vessels 20. Fibrous ingrowth 21. Copper deposition on Descemet’s membrane
■■Protocol for evaluation of angle structures Before commenting on the gonioscopic findings, the following protocol must be adopted in every case. Bright illumination causes the pupil to constrict and the angle to open up. Newer techniques are being developed to do infrared gonioscopy to undo this effect. The following points are important: 1. Dim illumination in the room where gonioscopy is being done 2. Adequate topical anesthesia 3. Shortest slit possible 4. Slit should not cross pupillary border 5. Low slit illumination 6. Set the slit lamp on the upper half of cornea
7. Off center the beam by 40–45 degrees 8. Insert gonioscope 9. View inferior-superior-nasal- and temporal angle (ISNT) 10. Always compare the findings in one eye with the fellow eye before commenting on the angle characteristics.
■■A brief overview of angle pathology Gonioscopy is initially performed to determine if the angle is open or closed.1 If the scleral spur is visible without manipulation, the angle is generally considered incapable of closure. A peripheral bulge in the iris may represent an anteriorly displaced ciliary body, typical of plateau iris configuration.2 The angle depth may not be uniform in the 360 degree angle circumference. Commonly the superior angle is narrower than the inferior angle. Nonuniform depth or areas of partial closure may result from peripheral anterior synechiae, cysts of the iris, a dislocated or subluxated crystalline lens and ciliary body tumors and cysts. Any intraocular surgery can also alter the angle width and lead to synechial closure. It is generally held that cataract surgery deepens the anterior chamber and opens up the angle. Previous laser trabeculoplasty must be ruled out as it can lead to various degrees of irido-trabecular synechiae. Peripheral anterior synechiae are not pathognomonic of any single entity, but may give a clue to the diagnosis.3 They tend to form superiorly first in angle closure glaucomas and inferiorly in uveitis. In the iridocorneal-endothelial (ICE) syndromes, they tend to extend anterior to the Schwalbe’s line, while they can occur in any location in a post-traumatic case. The pigmentation of the trabecular meshwork varies widely and increases with age. Very heavy pigmentation of the angle is almost always pathological. It is often seen in pigment dispersion syndrome, pseudoexfoliation syndrome, a malpositioned IOL (anterior or posterior chamber), following anterior uveitis or anterior segment reconstruction surgery and iris melanoma. Gray, white flakes like “Dandruff” in the angle are pathognomic of the pseudoexfoliation syndrome. Blunt trauma may lead to a posterior displacement of the ciliary body with an extra deep angle as compared to the other eye. Iridodialysis, cyclodialysis, angle recession, increased pigmentation, blood and foreign bodies may be seen in the angle.
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Gonioscopy: A Text and atlas
Special attention should be paid to the vasculature in the angle. Normal iris vessels may dilate in anterior uveitis and may be confused to neovascularization. However unlike new vessels these vessels are oriented radially and do not meander or branch. In congenital glaucoma, hairpin loops of vessels may be seen that may rarely extend anteriorly to the Schwalbe’s line. Abnormal vessels branch irregularly on the
iris surface and cross the scleral spur. These vessels however start and end in the iris and do not branch. In eyes affected with congenital glaucoma the most important gonioscopic finding is an anterior insertion of the iris onto the trabecular meshwork. The following chapters describe the angle findings in various ocular conditions.
■■References 1. Bruno CA, Alward WL. Gonioscopy in primary angle closure glaucoma. Semin Ophthalmol. 2002;17(2):59–68. Review.
2. Thomas R, Thomas S, Chandrashekar G. Gonioscopy. Indian J Ophthalmol. 1998;46(4):255–61. Review. 3. Terry JE. Gonioscopy: evaluation and interpretation. J Am Optom Assoc. 1977;48(11):1415–23.
Chapter 10
Primary Angle Closure Disease
A simple approach to assessment of the angle is to see whether or not the scleral spur is visible. a. Scleral spur visible - Indicates an open angle b. Scleral spur not visible – Do indentation/ manipulation gonioscopy and establish if closure is appositional or synechial. Primary angle closure glaucoma is one of the most common indications for gonioscopy (Figures 10.1 and 10.2). It is characterized by a narrow angle with an angle recess which is usually narrow than 20°. The following features need to be examined:1, 2 1. The width of the angle recess 2. Evidence of a previous angle closure attack– glaucomaflecken, sphincter atrophy, increased pigmentation, pattern of pigmentation 3. The presence and extent of goniosynechiae, peripheral anterior synechiae (PAS) 4. Symmetry of gonioscopic findings between the two eyes (An intumescent lens on one side may narrow the angle unilaterally) 5. Other pathology that may close the angle e.g. neovascularization of the angle Recently the widely used classification is based on natural history and is evidence based. This classification was introduced by the International Society of Ophthalmic Epidemiology and is well based on gonioscopy and ophthalmoscopy:
Figure 10.1 Chronic primary angle closure
1. Primary Angle Closure Suspect (PACS): Angle showing an appositional contact between peripheral iris and posterior trabecular meshwork. Epidemiologically this has been defined as an angle in which 180–270º of posterior trabecular meshwork is not visible in primary position (Figures 10.3 and 10.4). Neither elevated IOP, PAS, disc or visual field changes are associated. 2. Primary angle closure(PAC): PACS with statistically raised IOP and/ or synechiae without disc or visual field changes (Figures 10.5 – 10.8). 3. Primary angle closure glaucoma (PACG): PAC with glaucomatous optic neuropathy and corresponding visual field changes (Figures 10.9 and 10.10). Gonioscopy is thus on one of the main pillars to this classification and this is useful simple classification to screen and prognosticate the glaucoma patient.
■■Occludable Angle If the pigmented trabecular meshwork is not visible in at least three quadrants in primary position without manipulation, the angle can be labelled as occludable (Figures 10.11 – 10.13) and the patient is at an increased risk of developing angle closure glaucoma. This patient is also termed as an angle closure suspect. Such a patient requires a peripheral laser iridotomy. Other findings that point towards an increased risk of angle closure or a previous episode of closure are:
Figure 10.2 Narrow entry in the angle with convex iris configuration in a case of angle closure
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Gonioscopy: A Text and atlas
Figure 10.3 Primary angle closure suspect: posterior pigmented trabecular meshwork not visible
Figure 10.4 Primary angle closure suspect
Figure 10.5 Pigmentation anterior to Schwalbe’s line post acute attack of angle closure
Figure 10.6 Goniosynechiae in angle
Figure 10.7 Goniosynechiae in angle
Figure 10.8 Large goniosynechiae in angle
Primary Angle Closure Disease
Figure 10.9 Closed angle in PACG
Figure 10.10 Peripheral anterior synechiae
Figure 10.11 Occludable angle
Figure 10.12 Occludable angle
Figure 10.13 Occludable angle: high magnification
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Gonioscopy: A Text and atlas
1. Documented appositional or near appositional closure. 2. The presence of goniosynechiae or PAS 3. Increased in irregular, blotchy angle pigmentation— pigment indicates that at some point of time the iris was in contact with that angle structure, leaving a pigment remnant (Figure 10.14) 4. Convex configuration of the iris (Figure 10.15) 5. Angle closure in the fellow eye.
■■Chronic Primary Angle Closure Glaucoma This may develop after an attack of acute angle closure glaucoma or may be caused by a gradual closure or the long-term use of miotics. In this condition, portions of the anterior chamber angle are permanently closed by peripheral anterior synechiae and the intraocular pressure is chronically elevated.3, 4
■■Type 1 (creeping) This is characterized by a slow formation of peripheral anterior synechiae, that start superiorly and spreads circumferentially, moving the iris insertion gradually forward over the trabecular meshwork.5 The cause of the same is poorly understood, but multiple factors like pupillary block, iris thickness and position, and plateau iris configuration appear to be involved.
■■Type 2 This is caused by synechial angle closure as a result of intermittent (subacute) attacks secondary to pupillary block or following an attack of angle closure glaucoma.6
■■Type 3 (mixed) This is caused by a combination of POAG with narrow angles usually associated with the long-term use of miotics.
Figure 10.14 Pseudo-trabecular meshwork due to anterior pigmentation in a closed angle
Figure 10.15 Convex iris configuration
Figure 10.16 Peripheral anterior synechiae causing segmental angle closure
Primary Angle Closure Disease
Peripheral anterior synechiae are usually present but they involve 1800 of synechial angle closure may not benefit by a laser iridotomy.
■■Plateau Iris Configuration This is a peculiar type of angle configuration that has the potential for causing angle closure glaucoma. It is characterized by anteriorly positioned ciliary processes that critically narrow the anterior chamber recess by pushing the peripheral iris forward. It is far less common than pupillary block glaucoma and is recognized only after a peripheral irodotomy for a presumed pupillary block mechanism has failed.8,9 1. In these eyes the anterior chamber appears to be of normal depth while the iris appears to have a relatively flat approach to a crowded iridocorneal angle. 2. The iris appears to be on a plane to intersect with Schwalbe’s line. A steep drop-off occurs immediately before the trabecular meshwork, which usually allows the aqueous humor to flow out.
Figure 10.17 Flat iris at the centre with a drop off at the periphery suggestive of sine wave appearance: Plateau Iris Configuration
3. With indentation gonioscopy, the trabecular meshwork is visible and a peripheral hump can be seen in the iris where it drapes over the ciliary processes, which is called the ‘sine wave’ appearance (Figure 10.17). Part of this iris configuration may be attributed to a component of pupillary block—hence the need for these patients to undergo a peripheral laser iridotomy. If the eye develops angle closure and a raised IOP in the presence of a patent iridotomy, then the patient is said to have plateau iris syndrome. If the IOP remains normal, the eye is considered to have plateau iris configuration.
■■References 1. Curran EJ. A new operation for glaucoma involving a new principle in the etiology and treatment of chronic primary glaucoma. Arch Ophthalmol 1920;49:131. 2. Chandler PA. Narrow angle glaucoma. Arch Ophthalmol 1952;47:69. 3. Pollack IP. Chronic angle closure glaucoma. Diagnosis and treatment in patients with angles that appear open. Arch Ophthalmol 1971;85: 67. 4. Bhargava SK, Leighton DA, Phillips CI. Early angle closure glaucoma. Distribution of irodotrabecular contact and response to pilocarpine. Arch Ophthalmol 1973;89:369.
5. Lowe RF. Primary creeping angle closure glaucoma. Br J Ophthalmol 1964;48:544. 6. Chandler PA, Trotter RR. Angle closure glaucoma. Subacute types. Arch Ophthalmol 1955;53:305. 7. Forbes M. Gonioscopy with corneal indentation. A method for distinguishing between appositional closure and synechial closure. Arch Ophthalmol 1966;76:488. 8. Tornquist R. Angle closure glaucoma in an eye with plateau type of iris. Acta Ophthalmol 1958;36:413. 9. Ritch R. Plateau iris is caused by abnormally positioned ciliary processes. J Glau 1992;1:23.
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Chapter 11
Primary Open Angle Glaucoma
Primary open angle glaucoma (POAG) is the most prevalent form of all glaucomas.1 It is typically defined by the following three criteria: an intraocular pressure consistently above 21 mm Hg at least in one eye, an open normal appearing anterior chamber angle with no apparent ocular or systemic abnormality that might account for the elevated IOP and typical glaucomatous visual field and/or optic nerve head changes. The risk for POAG increases with age.2,3,4 Other described risk factors are family history, myopia, hypertension, pigmented race and diabetes. POAG is more common in western countries whereas angle closure is more common in Asian population. POAG is relatively asymptomatic until late in disease, the incidence increases with age and has no definite sex predilection. It is often referred to as the “sneak thief of sight”. POAG has a genetic predilection and over the years several modes of inheritance have been noted. The risk of monocular blindness ranges from 14.6–27% and bilateral blindness between 6.4–9% in various studies.
■■Anatomy of open angle
4. Trabecular meshwork 5. Schwalbe’s line. Blood vessels though normally not seen in the angle, they may appear in front of the ciliary body band and less commonly over the scleral spur and trabecular meshwork. These vessels travel circumferentially in the angle.
■■Root of iris It is the posterior most structure in the angle on gonioscopy. Deep in the angle it may demonstrate iris processes or in case if angle closure, peripheral anterior synechiae or gonio synechiae. Iris processes are histologically analogous to the iris and are continuous with it. They are a normal developmental variant in the angle (Figure 11.2). They arise from the peripheral iris, bridge the angle and insert on the scleral spur or the ciliary body. Occasionally, they may have a higher insertion on the Schwalbe’s line. They are fine and lacy conform to the iris and contract on exposure to bright light. Often torn iris processes are seen as a sign of blunt globe trauma.
The anterior chamber angle by definition is open and grossly normal (Figure 11.1). The angle recess is wide, iris configuration is regular and all structures are visible without the need of manipulation. The following structures can be seen in a normal open angle: 1. Root of the iris 2. Ciliary body band 3. Scleral spur
■■Ciliary body band
Figure 11.1 Wide open angle
Figure 11.2 Iris processes
It is located between the root of the iris and the scleral spur. The amount of ciliary body band visible depends upon how far anterior or posterior does the iris insert. The color is typically gray. Widened ciliary body band as compared to the other eye is indicative of angle recession post closed globe trauma.
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Gonioscopy: A Text and atlas
■■Scleral spur It is the anterior extension of the sclera between the ciliary body and the trabecular meshwork. It is usually visible as a bright white line. Sometimes it is obscured by uveal trabecular meshwork.
■■Trabecular meshwork It is located immediately posterior to the Schwalbe’s line. It has anterior non-pigmented and a posterior pigmented part. The posterior pigmented part is the functional part of the meshwork. It is non-pigmented and dull gray at birth and later acquires increasing amount of pigmentation.
■■Schwalbe’s line It is the most anterior structure in the angle. It is the termination of the Descemet’s membrane. It is the most
Figure 11.3 Juvenile open angle glaucoma: Open angle with multiple fine iris processes
important landmark while performing gonioscopy. The peripheral cornea terminates into a groove in the anterior sclera. This anatomy helps identify the Schwalbe’s line on gonioscopy. If a narrow slit beam is projected into the angle, the beams striking the inner and outer surface of the cornea will form a parellelopiped which will converge on the Schwalbe’s line. In certain conditions like Axenfeld Rieger syndrome, the Schwalbe’s line is anteriorly displaced and may be visible on slit lamp examination itself. In that case it is termed as prominent posterior embryotoxon.
■■Juvenile open angle glaucoma It is a subset of open angle glaucoma with early onset. The gonioscopic findings are (Figures 11.3–11.5): 1. The angle is usually widely open 2. Prominent iris processes may be seen 3. Iris insertion may be high 4. Angle is usually pigmented.
Figure 11.4 High insertion of iris
Figure 11.5 JOAG with increased angle pigmentation
Primary Open Angle Glaucoma
■■References 1. Quigley HA, Broman AT. The number of people with glaucoma worldwide in 2010 and 2020. Br J Ophthalmol 2006; 90:262–267.
3. Mitchell P, Smith W, Attebo K, et al. Prevalence of open angle glaucoma in Australia. The Blue Mountains Eye Study. Ophthalmology 1996; 103:1661–1669.
2. Tielsch JM, Sommer A, Katz J, et al. Racial variations in the prevalence of primary open angle glaucoma. The Baltimore Eye Survey. JAMA 1991; 266:369–374.
4. Klein BE, Klein R, Sponsel WE, et al. Prevalence of glaucoma. The Beaver Dam Eye Study. Ophthalmology 1992; 99:1499-1504.
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Chapter 12
Congenital and Developmental Glaucoma
Gonioscopy in infants is performed with a smooth domed Koeppe lens or the Swan-Jacob goniolens using the hand held slit lamp or the operating microscope (Figure 12.1 and 12.2). This may be done in physician’s office by distracting the child’s attention using toys or sweets. Chloral Hydrate sedation at doses of 30–50 mg/kg is a useful adjunct. Gonioscopy is valuable in distinguishing primary congenital glaucoma from secondary glaucomas and it also helps guide the surgical intervention. Gonioscopic features include: 1. The angle recess is absent in normal infants and the iris inserts flatly on the ciliary body face. 2. The trabecular meshwork has the appearance of a smooth, homogenous membrane, extending from the peripheral iris to the Schwalbe’s line. 3. The peripheral iris in infants tends to be thinner and flatter. 4. Very little or no pigmentation is seen.
■■Primary congenital glaucoma Primary congenital glaucoma occurs in 1 in 10000 births. 80% of all cases occur in the first year of life and about 65–80% of all cases are bilateral. Most cases are sporadic with no known
Figure 12.1 Direct gonioscopy with Koeppe’s lens in congenital glaucoma
family history. 10% of cases though are familial inherited as an autosomal recessive inheritance with high penetrance. Mutations on the 2p21 locus CYPIBI gene (cytochrome P4501B1) have been documented in patients with congenital glaucoma worldwide. The genetic loci mapped are GLC3A, mapped to the 2p21 region and GLC3B mapped to 1p36 region. Congenital glaucoma present at birth or within one month of birth is termed as newborn or birth-onset glaucoma. The most common presentation is between one month and 2 years of age. This is termed as infantile onset primary congenital glaucoma. From two years to ten years of age it is termed as late recognized primary infantile glaucoma. Congenital glaucoma occurs due to the developmental arrest of the anterior chamber angle tissue (embryologically from the neural crest cells). The angle is immature and trabeculo-dysgenesis is the only ocular anomaly in approximately 50%. This leads to a higher insertion of the iris and ciliary body onto the posterior trabecular beams which causes their compression and hinders aqueous outflow. Presentation may be with one or more of the classical triad of epiphora, blepharospasm and photophobia. The gonioscopic features are as follows: 1. The characteristic appearance is an open angle with high insertion of the iris root which forms a scalloped line.1
Figure 12.2 Gonioscopy with Swan-Jacob lens
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Gonioscopy: A Text and atlas
a. Most common form is where the iris inserts either at or anterior to scleral spur and the ciliary body is obscured by this insertion. The invisibility of ciliary body in these eyes is the key distinction from normal infant angle. The surface of trabecular meshwork may have a stippled orange peel appearance. The peripheral iris stroma may appear thinned and expose radial blood vessels. b. Iris may also insert concavely into the chamber angle. The plane of iris is posterior to the scleral spur, but the anterior stroma sweeps up on the trabecular meshwork and inserts just behind the Schwalbe’s line. Thus, the iris forms a wrap around insertion (Figure 12.3). 2. Abnormal tissue with a shagreen, glistening appearance may be seen in the angle, and appears to pull the peripheral iris anteriorly. 3. Loops of vessels from the major arterial circle may be seen above the iris root, which is called the Loch Ness monster phenomenon.2 4. The peripheral iris may be covered by a fine, fluffy tissue—the Lister’s morning mist.2
■■Axenfeld-Rieger Syndrome Axenfeld-Rieger syndrome is a spectrum of disease comprising of Axenfeld anomaly (posterior embryotoxon associated with high peripheral iridocorneal adhesions), Axenfeld syndrome (Axenfeld anomaly with glaucoma), Rieger anomaly (Axenfeld anomaly, iris stromal thinning, iris holes, corectopia), Rieger syndrome (Rieger anomaly with systemic developmental anomalies). It is inherited as an autosomal dominant trait. Several gene loci have been identified 4q25 (PITX2), 6p25 (FOXC1), 13q14
Figure 12.3 Wrap around iris
(REIG2). Glaucoma is thought to be due to an underlying trabeculodysgenesis due to the developmental arrest of the anterior segment tissue derived from the neural crest cells. The gonioscopic features are as follows: 1. Gonioscopy reveals a prominent anteriorly displaced Schwalbe’s line (posterior embryotoxon) as seen in Figures 12.4 and 12.5. The extent to which the Schwalbe’s line is enlarged and anteriorly displaced may vary between individuals. Sometimes the line is suspended from the cornea by a thin membrane [posterior embryotoxon, a term coined by Axenfeld, can also occur in 8–15% of general population].3, 4 2. Tissue strands bridge the anterior chamber angle from the peripheral iris to the prominent ridge (Figures 12.6–12.14). These adhesions are similar in color and texture to the adjacent iris. The strands vary from threadlike structures to broad bands. 3. The angle however is open and the meshwork may be seen through the strands. 4. The scleral spur is obscured by the peripheral iris which inserts into the posterior part of the meshwork.5
■■Aniridia Aniridia is associated with glaucoma in approximately 50–70% of cases. Despite the name a rudimentary stump of the iris is usually present and evident on gonioscopy (Figures 12.15 and 12.16). Aniridia is associated with multiple ocular defects some of which are present at birth while some manifest later in life. It is inherited as an autosomal dominant trait with mutations in the PAX6 gene locus on 11p13. 30% of cases show sporadic inheritance. The sporadic cases have a high-risk of systemic association with Wilm’s tumor. The angle is usually open in infancy. Some patients have strands of tissue with occasional fine blood vessels extending from the iris root to the trabecular meshwork or higher.6 During
Figure 12.4 Posterior embryotoxon on diffuse illumination in Axenfeld anomaly
Congenital and Developmental Glaucoma
Figure 12.5 Posterior embryotoxon on gonioscopy in Axenfeld anomaly
Figure 12.6 Anteriorly displaced Schwalbe’s line with iridocorneal adhesions in Axenfeld Rieger syndrome
Figure 12.7 Fine iridocorneal adhesion in Axenfeld anomaly
Figure 12.8 Periphral iridocorneal adhesion in Axenfeld Rieger syndrome
Figure 12.9 Periphral iridocorneal adhesion in Axenfeld Rieger syndrome
Figure 12.10 Periphral iridocorneal adhesion in Axenfeld Rieger syndrome
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Gonioscopy: A Text and atlas
Figure 12.11 Periphral iridocorneal adhesion in Axenfeld-Rieger syndrome
Figure 12.12 Rieger Anomaly: Peripheral and Mid Peripheral Irido Corneal Adhesions
Figure 12.13 Rieger Anomaly: Peripheral and Mid Peripheral Irido Corneal Adhesions
Figure 12.14 Rieger Anomaly: Peripheral and Mid Peripheral Irido Corneal Adhesions
Figure 12.15 Aniridia: angle showing closed angle on gonioscopy with iris stump and ciliary processes visible
Figure 12.16 Aniridia: angle showing open angle on gonioscopy with iris stump and ciliary processes visible
Congenital and Developmental Glaucoma
the first 10–15 years of life, the angle progressively closes as the rudimentary stump of the iris comes to lie over the trabecular meshwork.7 The gonioscopic appearance correlates with the development of glaucoma.
■■IridoFundal Coloboma
Angle anomaly can be seen with primary as well as secondary developmental glaucomas. There can be anterior insertion of iris, prominent iris processes (Figures 12.19 and 12.20) and featureless angle. Iris processes represent the remnant of normal embryological development of angle and can be a normal variation as well.
Gonioscopy can be used to assess the angle structures (Figures 12.17 and 12.18).
Figure 12.17 Iridofundal coloboma
Figure 12.18 Iridofundal coloboma: gonioscopy
Figure 12.19 Prominent iris processes
Figure 12.20 Developmental glaucoma with prominent iris processes
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■■References 1. Walton DS. Primary congenital open angle glaucoma. In: Glaucoma. Chandler PA, Grant WM, eds. Philadelphia. Lea and Febiger. 1979, p. 329. 2. Worst JGF. The pathogenesis of Congenital Glaucoma. An Embryological and Goniosurgical Study. Springfield, IL. Charles C Thomas 1966. 3. Shields MB. Axenfeld Rieger syndrome. A theory of mechanism and distinctions from the iridocorneal endothelial syndrome. Trans Am Ophthalmol Soc 1983;81:736. 4. Wolter JR, Sandall GS, Fralick FB. Mesodermal dysgenesis of anterior eye with a partially separated posterior embryotoxon. J Pediatr Ophthalmol Strabismus 1967;4:41.
5. Burian HM, Braley AE, Allen L. External and gonioscopic visibility of the ring of Schwalbe and the trabecular zone. An interpretation of the posterior corneal embryotoxon and the so called congenital hyaline membranes on the posterior corneal surface. Trans Am Ophthalmol Soc 1955;51:389. 6. Grant WM, Walton DS. Progressive changes in the angle in congenital aniridia with development of glaucoma. Am J Ophthalmol 1974;78:842. 7. Margo CE. Congenital aniridia: A histopathologic study of the anterior segment in children. J Pediatr Ophthalmol Strabismus 1983;20:192.
Chapter 13
Angle Pathologies
■ NEOVASCULAR GLAUCOMA Neovacularization develops in response to retinal ischemia. The overall incidence and prevalence of neovascular glaucoma (NVG) is 3.9%. 1 Approximately 36% of NVG occurs after central retinal vein occlusion, 32% with proliferative diabetic retinopathy and 13% after carotid artery occlusion.2 The disease is more prevalent in older age group in patients who have significant cardiovascular risk factors like hypertension, diabetes, dyslipidemia and in smokers. Other uncommon causes are branch retinal vein occlusion, carotico-cavernous fistula, external beam irradiation, chronic retinal detachment, Takayasu arteritis, etc. The ischemic retina releases vascular endothelial growth factor (VEGF) which is a vasoproliferative substance. It acts on receptors on capillaries to stimulate growth of neo vessels. In cases where retina is extremely hypoxic, there are essentially very few viable retinal capillaries. In such cases, VEGF diffuses forward to the posterior iris. Fluorescein angiography of the anterior segment may be contributive to the early diagnosis of rubeosis iridis. The disease is divided into three stages: 1. Preglaucoma stage 2. Openangle glaucoma stage 3. Angleclosure glaucoma stage.
■ Preglaucoma Stage This stage is characterized by a normal IOP, unless preexisting chronic openangle glaucoma is present. Dilated tufts of pre-existing capillaries, with randomly oriented vessels on the surface of the iris appear at the pupillary margin. These vessels are characterized by leakage of fluorescein. Usually neovascularization appears first on the pupillary margin, but it may be first seen in the anterior chamber angle.3 Angle neovascularization is characterized by: 1. Single vascular trunks which cross the scleral spur 2. Arborizes on the trabecular meshwork (Figure 13.1) 3. Does not follow any regular, radial or circumferential pattern like normal blood vessels but meander in an irregular fashion.
Figure 13.1. Neovascular glaucoma with neo vessel in the angle
4. Leaks fluorescein in anterior segment angiography 5. The trabecular meshwork may take on a reddish coloration 6. Spontaneous hyphemas
■ Open Angle Glaucoma Stage These vessels are accompanied by a fine fibrous membrane.4,5 The angle may appear open on gonioscopy but actually the fibrous membrane is obstructing the aqueous flow. The fibrous membrane is usually invisible on gonioscopy and may only be demonstrated on histopathologic examination of the trabecular meshwork. A rise in IOP occurs in this apparently open angle with the presence of a turbid aqueous (increased leakage of protein). The importance of gonioscopy lies in the fact that angle neovascularization can occur in the absence of iris neovascularization.
■ Angle Closure Glaucoma stage 1. The fibrovascular membrane which accompanies neovascularization of the angle has a tendency to contract and pull the vessels taught, bridging the angle initially and then tenting the iris towards the trabecular meshwork, leading to PAS formation (Figure 13.2).6 2. As these synechiae coalesce, synechial angle closure develops.7 3. The stroma of the iris becomes flattened assuming a smooth, glistening appearance.
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Gonioscopy: A TexT And ATlAs
Figure 13.2. Neovascular glaucoma: closed angle with neovascularization of iris
4. The radial traction along the surface of the iris pulls the posterior pigment layer of the iris around the pupillary margin, onto the anterior iris surface—Ectropion uveae. 5. Eventually total synechial closure develops. The examiner should be careful as the new vessels may regress and sometimes a pigmented Schwalbe’s line can be mistaken for the trabecular meshwork and the angle labeled as being open, while actually it is closed. The corneal wedge method should be used to identify the angle structures. The fibrovascular membrane cannot grow over the healthy corneal endothelium, the PAS therefore ends at the Schwalbe’s line, which distinguishes this condition from secondary angle closure glaucomas that results from an abnormal corneal endothelium such as the ICE syndrome. Rarely, anterior segment neovascularization may occur without demonstrable retinal ischemia, as in Fuch’s heterochromic iridocyclitis and other types of uveitis, exfoliation syndrome, or isolated iris melanomas. When an ocular cause cannot be found, carotid artery occlusive disease should be considered (Figures 13.3–13.4). It is also important to distinguish between dilated iris vessels associated with inflammation from newly formed abnormal blood vessels.
Figure 13.3 Ocular ischemic syndrome with cataract, ectropion uveae
Figure 13.4 Ocular ischemic syndrome with closed angle
■ IRIDOCORNEAL ENDOTHELIAL (ICE) SYNDROME These rare disorders share a typical corneal endothelial abnormality that causes varying degrees of corneal edema, iris atrophy, and secondary angle closure glaucoma (Figure 13.5–13.12). They are usually unilateral and the diagnosis of ICE should be considered in young to middle-aged patients who present with unilateral angle closure glaucoma. It is more common in females. There are three variants of the disease:
Figure 13.5 Iridocorneal endothelial syndrome
Angle pathologies
Figure 13.6 Chandler variant of ICE syndrome
Figure 13.9 Progressive iris atrophy
Figure 13.7 PAS extending anterior to Schwalbe’s line
Figure 13.10 Irido corneal adhesion in ICE
Figure 13.8 Progressive iris atrophy: corectopia
Figure 13.11 Cogan–Reese syndrome
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Gonioscopy: A TexT And ATlAs
■ LENS INDUCED GLAUCOMAS
Figure 13.12 Irido corneal adhesion in Cogan–Reese syndrome
• Chandler’s syndrome—Changes in iris are mild, corneal edema predominates often with edema even at normal intraocular pressures. • Iris nevus/Cogan-Reese syndrome—Nodular, pigmented lesions of iris are the hallmark and may be seen with a spectrum of corneal and other iris defects. • Essential iris atrophy—Iris changes predominate with marked corectopia, atrophy and hole formation. There is a hammered silver/gray appearance to the corneal endothelium which is clearly evident on slit lamp examination. Specular microscopy shows polymegathism and pleomorphism with dark areas with only a light central spot and light peripheral zone. These cells are called ICE cells. The abnormal endothelial cells with epithelial properties, migrate over the anterior chamber angle and onto the iris surface. This causes formation of peripheral anterior synechiae. Confocal microscopy demonstrates “epithelial” like changes in the endothelium. Exact cause is not known but Herpes or an Epstein–Barr viral etiology has been postulated. The progressive iris atrophy is characterized by marked iris atrophy with variable degrees of corectopia and ectropion uvea. The hall mark of progressive iris atrophy is hole formation which are of two forms either a stretch hole or a melting hole. Although the anterior chamber angle abnormalities may be found in all variations of iridocorneal endothelial syndrome the associated glaucoma appears to be more common in progressive iris atrophy and Cogan–Reese syndrome. The peripheral anterior synechiae in ICE syndrome tend to extend anterior to the Schwalbe’s line and close the anterior chamber angle causing glaucoma.8 PAS results from contraction of single or multiple layers of endothelial cells and the surrounding fibrous tissue that extends from the corneal endothelium onto the trabecular meshwork and the iris. The degree of synechial closure does not correlate with the IOP as the trabecular meshwork may be functionally closed by the endothelial membrane without synechial closure.
Lens induced glaucomas can be either open angle mechanism based or closed angle. Open angle lens induced glaucoma is of three types: phacolytic, phacoanaphylactic and lens particle glaucoma. 1. Phacolytic glaucoma: This entity was named by Flocks et al. in 1955. It is associated with hypermaturity of crystalline lens with liquefaction of lens cortex and passage of lens proteins through the lens capsule. The patients are typically elderly and present with sudden painful diminution of vision with prior history of diminished vision due to cataract. Examination reveals elevated intraocular pressure with corneal edema, prominent flare reaction and anterior chamber cells. a. Gonioscopy exhibits an open angle and is grossly normal. b. It may be difficult to comment on angle status at instances due to corneal edema and anterior chamber inflammation. c. Chunks of white material may be seen in aqueous, anterior lens capsule and angles which may consist of macrophages, lens protein and calcium oxalate or cholesterol crystals. The lens exhibits advanced cataractous change of Morgagnian nature with liquefied cortex. Medical treatment with aqueous suppressants and corticosteroid is to be initiated preoperatively followed by extracapsular cataract extraction with PCIOL implantation which forms the definitive treatment. 2. Lens particle glaucoma: Elevated IOP here is due to retained lens material in aqueous. This entity is associated with antecedent trauma with disruption of lens capsule or an intraocular surgery like an ECCE or phacoemulsification. It is characterised by lens fragments in the anterior chamber. Eye remains congested with elevated IOP, corneal edema and marked cell and flare reaction. a. Gonioscopy may reveal lens particle overlying the trabecular meshwork. Diagnosis can be confirmed by anterior chamber paracentesis wherein the samples retrieved would show lens particle and macrophages. Treatment consists of aqueous suppressants, topical steroids and cycloplegics. Surgical treatment may be needed if medical treatment fails or if patient has pre-existing glaucoma and if patient is in early postoperative period. 3. Lens induced uveitis: This entity was initially termed endophthalmitis phacoanaphylactica by Verhoeff in 1922. It is more appropriately known as lens induced uveitis as it is an inflammation seen due to abnormal intolerance to self-antigens with intense intra ocular inflammation induced by residual lens material in eye. It is charecterized by zonal granulomas formed by concentric layers of macrophages, lymphocytes, multi nucleated giant cells and epitheloid cells surrounding
Angle pathologies
the lens material. It may present hours to months after surgery or trauma. Severe inflammation and sterile hypopyon may be seen on gonioscopy. Low intraocular pressure may be seen in these patients. Medical treatment consists of topical and systemic corticosteroids, cycloplegics. However definitive treatment is removal of all residual lens matter. Lens induced angle closure mechanisms include phacomorphic glaucoma and phacotopic glaucoma. 1. Phacomorphic glaucoma : An intumescent or hypermature cataractous lens may narrow the angle and cause glaucoma. This is termed as phacomorphic glaucoma. If the condition persists over 72 hours, usually peripheral anterior synechiae develops which causes angle closure glaucoma. However in this case there is no iris bombe and the chamber is uniformly shallow. Cataract extraction can reduce the IOP but if peripheral anterior synechiae develop a combined cataract extraction with trabeculectomy may be needed. The fellow eye may have an open angle, distinguishing it from primary angle closure glaucoma. 2. Phacotopic glaucoma: It is angle closure secondary to the position of the lens. Ectopia lentis can lead to pupillary block with typical iris bombe formation and closure of the angle (Figure 13.13). Uveitis associated with lens induced glaucomas can cause inflammatory debris to accumulate in the iridocorneal angle. This may cause the iris to adhere to the trabecular meshwork leading to PAS formation.
pseudoexfoliation develop raised IOP of which about 30% develop glaucoma. Patients with pseudoexfoliation with raised IOP are twice as likely to develop open angle glaucoma as compared to normals. Glaucoma in pseudoexfoliation is more resistant to medical therapy than POAG. The pathology is chronic accumulation of abnormal fibrillar matrix product. The theory proposed is that of a stress induced elastosis. It is an elastic microfibrillopathy associated with excessive production of elastic microfibrils and their aggregation into typical mature fibrils by a variety of potential elastogenic cells. 1. Gonioscopy reveals the presence of increased pigmentation (moderate to dense) on the trabecular meshwork (Figures 13.14 – 13.16).9
■ PSEUDOEXFOLIATION SYNDROME This condition is characterized by the deposition of fibrillar protein material throughout the anterior segment of the eye. Exfoliation material tends to be deposited on the corneal endothelium, anterior surface of the lens, the iris, on the zonules and the ciliary body. About 25% of patients with
Figure 13.13 Secondary angle closure due to subluxation of lens
Figure 13.14 Target sign: Pseudoexfoliation syndrome
Figure 13.15 Exfoliative material at pupillary margin
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■ PIGMENT DISPERSION SYNDROME
2. Pigment may be deposited anteriorly to the Schwalbe’s line (Sampaolesi line) also. 3. The distribution in the meshwork tends to be uneven or splotchy, less black and well-defined when compared to the pigment dispersion syndrome. It follows a discontinuous segmental fashion. 4. Flecks of exfoliation material may be seen adherent to the trabecular meshwork. 5. Weakness of the zonules with subluxation or dislocation of the lens may be seen. 6. The severity of pigment or exfoliative material does not correlate with the severity of glaucoma. 7. Narrow angles may be seen in 23–32% of patients with peripheral anterior synechiae in 10–15% cases.
This is a bilateral disorder characterized by the liberation of pigment from the iris pigment epithelium and its deposition throughout the anterior segment. The diagnostic triad consists of slit like mid peripheral iris transillumination defects, diffuse and dense brownish pigmentation of the anterior chamber angle and pigment granules on the corneal endothelium (Krukenberg spindle Figures 13.17 and 13.18). When accompanied by glaucoma the term used is pigmentary glaucoma. The typical patient affected is a young myopic male. The male to female ratio is 3:1. The disease process can be divided into three phases. The first is the active pigment dispersion phase which can start as early as the mid teens. During this phase pigment is actively liberated which starts accumulating in the anterior chamber structures. This phase is mostly asymptomatic but in few individuals there may be an acute attack type of a picture due to sudden liberation of pigment after physical exertion, stress or a drug induced mydriasis especially after phenylephrine. The second stage is the conversion stage wherein 10% of pigment dispersion cases eventually develop glaucoma over 5 years. The third stage is a possible self-healing stage wherein the pigment starts clearing as time passes and the IOP falls. It is hypothesized that in these eyes, the iris is more posteriorly inserted on the sclera, the anterior chamber is deeper than normal and the iris stroma is floppy. This causes a posterior bowing of the iris tissue which rubs on the zonules. This rubbing releases pigment from the posterior iris epithelium with loss of melanosomes. 1. The angle is usually open with a deep anterior chamber.
Figure 13.17 Pigment dispersion syndrome – Krukenberg spindle
Figure 13.18 Pigment dispersion syndrome—Krukenberg spindle
Figure 13.16 Exfoliative material in angle: Pseudoexfoliation syndrome
Angle pathologies
2. The iris assumes a marked concave configuration most prominently in the midperiphery (Figure 13.19). 3. Pigmentation may be noted anterior to the Schwalbe’s line (Sampaolesi line, Figures 13.20 and 13.21). 4. The pigment deposition in the angle unlike in pseudoexfoliation is a homogenous dense, very dark band (muscara line) covering the trabecular meshwork, sometimes extending to the scleral spur (Figure 13.22– 13.26).10 5. The normal angle structures may be obscured. 6. The severity of glaucoma seems to correlate with the amount of pigment deposition in the angle.
■ UVEITIC GLAUCOMA The angle may be open or closed in uveitic glaucoma. Open angle glaucoma may be due to hypersecretion of aqueous humor, trabecular obstruction by serum components or
trabecular precipitates, trabeculitis, scarring of trabecular meshwork or corticosteroid induced. Closed angle glaucoma may be due to pupillary block, iris bombe, PAS, anterior rotation of lens iris diaphragm or neovascularization. Gonioscopy helps to study the etiology of uveitis and the damage to the angle. Uveitis can cause rise in IOP both during the acute phase and the chronic healed phase. In the acute phase usually the IOP is low due to a cyclitis which causes aqueous suppression. But sometimes the component of trabeculitis is larger as occurs in herpetic etiology. This causes obstruction to the outflow and causes raised IOP. In the chronic stage, there may be multiple peripheral anterior synechiae and various amount of post inflammatory scarring of the trabecular meshwork which cause secondary glaucoma. The following findings may be noted on gonioscopic examination: 1. Inflammator y precipitates on the trabecular meshwork.
Figure 13.19 Concave iris configuration in Pigment Dispersion syndrome
Figure 13.21 Sampaolesi line
Figure 13.20 Sampaolesi line in Pigment Dispersion syndrome
Figure 13.22 Heavily pigmented angle in Pigment Dispersion syndrome
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Figure 13.23 Heavily pigmented angle in Pigment Dispersion syndrome: high magnification
Figure 13.25 Heavily pigmented angle in Pigment Dispersion syndrome (mascara line pigmentation): high magnification
Figure 13.24 Heavily pigmented angle in Pigment Dispersion syndrome (mascara line pigmentation): high magnification
Figure 13.26 Heavily pigmented angle in Pigment Dispersion syndrome
2. Peripheral anterior synechiae—they may occur due to a swollen and sticky iris. These synechiae are usually broad based and may close the angle and cause secondary glaucoma (Figures 13.27 – 13.38). 3. Iris bombe may occur due to pupillary block. 4. Neovascularization of the angle may be seen in chronic uveitis cases. 5. In Fuch’s heterochromic iridocyclitis – fine vessels may be noted in the angle, which usually do not form PAS. These vessels can bleed on paracentesis of the eye during surgery (Amsler’s sign) or while doing gonioscopy.
patients may not give a history of trauma as the time interval between the onset of late post-traumatic glaucoma and the injury may be more than 10–20 years.11 Gonioscopy must be performed in any patient who presents with an unexplained unilateral glaucoma. It helps the examiner to assess the angle damage and gives information about the risk for future development of glaucoma. It also helps in the localization of occult foreign bodies in the angle, in eyes with an open globe injury. It is generally advisable to defer gonioscopic assessment for six weeks after the injury to avoid further damage to ocular structures and precipitate bleeding into the anterior chamber (Figures 13.39 – 13.64). The following signs may be noted in a patient with blunt trauma: 1. A bleeding vessel may be noted. 2. Angle structures may be obscured by a layer of fibrin or blood clot.
■ POST-TRAUMATIC GLAUCOMA Gonioscopy is an invaluable tool for identifying the signs of old concussion trauma. This is important because many
Angle pathologies
Figure 13.27 Peripheral anterior synechiae in uveitic glaucoma
Figure 13.30 Uveitic glaucoma
Figure 13.28 Peripheral anterior synechiae with irregular angle pigmentation
Figure 13.31 Uveitic glaucoma
Figure 13.29 Areas of irregular pigmentation with synechiae in uveitic glaucoma
Figure 13.32 Uveitic glaucoma: pigment clumps
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Figure 13.33 Uveitic glaucoma: pigment clump
Figure 13.36 Uveitis: inflammatory exudates in angle
Figure 13.34 Broad based synechiae In uveitis
Figure 13.37 Uveitis: Inflammatory exudates in angle
Figure 13.35 Uveitis: Pseudo Trabecular Meshwork
Figure 13.38 Sarcoid: Inflammatory nodule in angle
Angle pathologies
Figure 13.39 Post-traumatic angle recession with PAS
Figure 13.41 Wide ciliary body band suggestive of angle recession
Figure 13.40 Angle recession
Figure 13.42 Angle recession: low magnification
Figure 13.43 Angle recession: high magnification
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Figure 13.44 Angle recession
Figure 13.45 Wooden stick in the angle
Figure 13.46 Synechiae in a case of post-traumatic glaucoma
Angle pathologies
Figure 13.47 Synechiae in a case of post-traumatic glaucoma
Figure 13.50 Post-traumatic cyclodialysis cleft
Figure 13.48 Blood in angle
Figure 13.51 Post-traumatic cyclodialysis cleft
Figure 13.49 Post-traumatic angle recession and cyclodialysis
Figure 13.52 Iris incarceration at the site of entry wound in a case of repaired corneal perforation
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Figure 13.53 Membranous growth in angle in a case of repaired corneal perforation
Figure 13.56 Post-traumatic iridodialysis
Figure 13.54 Post-traumatic iridodialysis
Figure 13.57 Irregular pigmentation with pigment clumps in a case of post-traumatic glaucoma
Figure 13.55 Post-traumatic iridodialysis
Figure 13.58 Post-traumatic glaucoma: diffuse and dense pigmentation
Angle pathologies
Figure 13.59 Foreign body in angle
Figure 13.60 Foreign body in angle
Figure 13.61 Foreign body in angle
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Figure 13.62 Post-traumatic iris cyst
Figure 13.63 Closed angle in iris cyst
Figure 13.64 Closed angle in iris cyst
Angle pathologies
3. 4. 5. 6.
7. 8. 9.
10.
Tears in the trabecular meshwork may be seen (rarely). Goniosynechiae. Increased irregular pigmentation Scleral spur may appear abnormally white. The underlying sclera is more visible through the thin remnant of the longitudinal ciliary muscle, which remains attached to the ciliary body. Retrodisplacement of the iris root. Rupture of normally present iris processes. A gray white membrane may be seen covering the angle recess many years after injury (fibrosis of the angle). Angle recession: This is the most important sign which points to a concussion injury to the globe. It refers to a broadened ciliary body band (as compared to the fellow eye) due to a tear between the longitudinal and circular muscles of the ciliary body. The presence of an irregularly broadened ciliary body and an asymmetry
between the two eyes establishes the diagnosis of angle recession. The amount of angle recession determines the risk of development of glaucoma, which is highest when the recession is more than 270 degrees. Angle recession perse does not cause glaucoma, it is only an indicator/ marker of trabecular injury. It is the accompanying trabecular meshwork damage that is responsible for the development of glaucoma.
■ NEOPLASTIC ACTIVITY Iris and ciliary body tumors can lead to glaucoma and gonioscopy may be the first to pick up signs of anterior chamber neoplastic activity. The mechanism of glaucoma may be a direct invasion of the angle, neovascularization, pressure on the lens, tumor pushing the peripheral iris forward and closing the angle, inflammation and tumor necrosis (Figures 13.65 – 13.70).12
Figure 13.65 Limbal ocular surface squamous neoplasia
Figure 13.67 The mass seen as a brownish opacity on gonioscopy: high magnification
Figure 13.66 The mass seen as a brownish opacity on gonioscopy
Figure 13.68 Ciliary body tumor invading into angle
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Figure 13.69 Ciliary body tumor invading into angle: gonioscopic view
Figure 13.71 Fibrous downgrowth
shallowing and flattening of the anterior chamber and increased IOP. Gonioscopy reveals completely closed angles with peripheral irido corneal adhesions. This entity does not show improvement with miotics and on the contrary shows lowering of IOP with mydratic and cycloplegics, aqueous suppressants and osmotic treatment. This condition is usually cured by disruption of anterior hyaloid face by laser or vitreous surgery.
■ Epithelial and Fibrous Downgrowth Figure 13.70 Ciliary body melanoma eroding into angle
Iris and ciliary body melanomas may have the following gonioscopic features: 1. The tumor appears as a chocolate brown mass sitting on the angle. Some tumors may be non-pigmented. Prominent telangiectasia on tumor surface may be seen and is characteristic. 2. Black hypopyon: necrotic debris in the angle may be seen. 3. Angle neovascularization may also be seen. 4. The iris may be pushed forward closing the angle in a particular quadrant.
■ GLAUCOMA AFTER ANTERIOR SEGMENT SURGERY ■ Malignant Glaucoma The term first coined by von Graefe is a complication that occurs after an intraocular surgery characterized by axial
Epithelial and fibrous downgrowth (Figure 13.71) are rare surgical complications which can lead to secondary angle closure. The predisposing factors are hypotony and fistula. Of the two the former has a graver prognosis. Epithelial tissue can be differentiated from fibrous tissue by treating the suspected tissue with argon laser—epithelial tissue characteristically turns fluffy (popcorning). Surgical removal or destruction of the pathologic tissue can be helpful treatment option. Medical and surgical treatment may be ineffective.
■ Aphakic and Pseudophakic Glaucoma It may be due to open and closed angle pathophysiologic entities. The causative mechanisms are many depending on whether the onset of rise in IOP is early, intermediate or late. Gonioscopy may reveal blood in angles, lens particle, vitreous, heavy pigmentation of the angles with associated iris transillumination defects in open angle conditions (Figures 13.72 – 13.94). In angle closure mechanisms gonioscopy may reveal inflammatory membranes, epithelial downgrowth, malignant glaucoma, sutures distorting the angle, peripheral anterior synechiae due to iridovitreal block, pupillary block, anteriorly vaulted IOL, haptics in angle, etc.
Angle pathologies
Figure 13.72 Vitreous in angle in aphakic glaucoma
Figure 13.75 Vitreous wick syndrome: magnified view
Figure 13.73 Steel sutures visible through the gonioscope
Figure 13.76 Prolene haptic in angle
Figure 13.74 Vitreous wick syndrome
Figure 13.77 Haptic in angle causing repeated uveitis and glaucoma in pseudophakia
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Figure 13.78 Pseudophakic glaucoma: Optic and haptic of posterior chamber intraocular lens in angle
Figure 13.81 Post extracapsular cataract extraction increased pigmentation of angle
Figure 13.79 Phakic IOL causing angle closure
Figure 13.82 Post extracapsular cataract extraction synechiae
Figure 13.80 Lens epithelial cell proliferation in inferior angle
Figure 13.83 Iris adhered to ECCE wound
Angle pathologies
Figure 13.84 10-0 MFN suture in angle
Figure 13.87 Post penetrating keratoplasty glaucoma showing synechiae at graft host junction
Figure 13.85 10-0 MFN suture in angle: high magnification
Figure 13.88 Post penetrating keratoplasty glaucoma
Figure 13.86 10-0 MFN suture
Figure 13.89 IOL haptic in angle lying near PI
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Figure 13.90 IOL haptic coming through PI in angle
Figure 13.92 Suture with synechiae in angle: pseudophakic glaucoma
Figure 13.91 Broken haptic in angle
Figure 13.93 Haptic of intraocular lens in angle with dense adhesions around it: pseudophakic glaucoma
Figure 13.94 Iris claw lens with synechiae in angle
Angle pathologies
Gonioscopy is also helpful in identification of the cause for pseudophakic glaucoma, especially in eyes with an anterior chamber IOL. The relationship of the haptic with the angle structures is clearly visible on gonioscopy. Gonioscopy is a vital part in the preoperative evaluation for patients with high refractive errors who want to undergo phakic IOL implantation. Secondary IOL implantation in aphakia also must be preceded by a thorough study of the entire circumference of the angle. Any area of PAS should be noted and IOL haptics positioned away from these areas.
■ Glaucoma After Posterior Segment Surgery
not uncommon. Post vitreoretinal surgery increase in IOP can be due to pupillary block which can be avoided with an inferior iridectomy. Most of the patients with increase IOP respond to medical management. In early postoperative period increased IOP can be due to overfill of silicone oil with shallow anterior chambers. Secondary glaucomas have also been noted with emulsified silicone oil blocking the trabecular meshwork (Figures 13.95 – 13.99). Histopathology has shown obstruction of trabecular meshwork by minute silicone bubbles, pigmented cells, silicone laden macrophages. Scleral buckling has also been associated with secondary glaucoma as a result of shifting of lens-iris diaphragm anteriorly or due to choroidal effusions.
With recently vitreoretinal surgery gaining its pace, secondary glaucoma postposterior segment surgery is also
Figure 13.95 Silicone oil droplets in angle
Figure 13.96 Emulsified Silicone oil droplets in angle
Figure 13.97 Emulsified Silicone oil droplets in angle
Figure 13.98 Emulsified Silicone oil droplets in angle
Figure 13.99 Silicone oil bubble in angle
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■ ELEVATED EPISCLERAL VENOUS PRESSURE INDUCED GLAUCOMA
■ POST SURGICAL EVALUATION OF ANTERIOR CHAMBER ANGLE
A carotid-cavernous fistula, dural sinus fistula, AV malformation in the orbit, orbital venous compression, orbital varices, superior vena cava syndrome and the Sturge – Weber syndrome are all conditions associated with a raised episcleral venous pressure. Examination reveals markedly engorged vessels in the episclera, conjunctival chemosis, proptosis may also be seen with ocular pulsations in eyes with AV fistula and an audible bruit. Goniocopic examination can demonstrate blood in the Schlemm’s canal.13 Some cases may develop angle closure due to choroidal effusion or suprachoroidal hemorrhage, while neovascular glaucoma can also be seen due to ischemia.
Gonioscopic evaluation is of importance in determining the outcome of a glaucoma filtering surgery. After a trabeculectomy, the view from the gonioscope shows a cleft in the sclera at the level of the scleral spur from where the block of tissue was removed during surgery (Figures 13.100 to 107). One can see if the iris tissue or any other material which is adherent to and blocking the site of the fistula. Laser can be used to open the blockage. Following the new glaucoma surgery of deep sclerectomy, laser is performed under gonioscopic visualization to penetrate the Descemet’s membrane, to enhance the success rate of surgery.
Figure 13.100 Synechiae in a case of operated trabeculectomy
Figure 13.102 Ostium in trabeculectomy
Figure 13.101 Surgical PI and ostium
Figure 13.103 Internal sclera opening in trabeculectomy
Angle pathologies
Figure 13.104 Internal sclera opening in trabeculectomy
Figure 13.105 Ostium in trabeculectomy blocked by iris
Figure 13.107 Releasable suture in trabeculectomy
Figure 13.106 Ostium in trabeculectomy blocked by iris
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■ GLAUCOMA DRAINAGE DEVICES The idea of implanting materials to shunt aqueous from the anterior chamber dates back to 1906. In the beginning variety of materials were used to serve as wicks to drain the aqueous from the anterior chamber to sub-conjunctival space. Most of these implants were solid materials rather than setons (tubular). The first of modern glaucoma drainage implants was designed by Molteno. The glaucoma drainage implants have a silicone tube that shunts aqueous humor to an end plate located in the
equatorial region of the globe. A fibrous capsule forms around the endplate after implantation which remains non adherent to the end plate and aqueous pools in the space between the endplate and the overlying capsule. This aqueous then drains out through the capsule by diffusion or absorption by periocular capillaries. The tube inserted can get migrated or obstructed. Migration of the tube further into the eye can be visualized through the slit lamp itself but if the tube has slipped out, the end of tube can be tried to visualize using a gonioscope. The obstruction of the tube by iris, vitreous or blood can be better visualized using a gonioscope (Figures 13.108 – 13.113).
Figure 13.108 Ahmed glaucoma valve
Figure 13.109 Gonioscopy showing Ahmed Glaucoma Valve in angle
Figure 13.110 Gonioscopy showing ahmed Glaucoma Valve blocked with iris
Figure 13.111 Gonioscopy showing: Express shunt in angle
Angle pathologies
Figure 13.112 Gonioscopy showing drainage device in angle
Figure 13.113 Gonioscopy showing drainage device in angle: magnified view
■ REFERENCES 1. Mocanu C, Barascu D, Marinescu F. Neovascular glaucoma- retrospective study. Ophthalmologica 2005;49:58–65. 2. Vancea PP, Abu-Taleb. Current trends in neovascular glaucoma treatment. Rev Med Chir Soc Med Nat Iasi 2005;109:264–268.
8. Shields MB: Axenfeld Rieger syndrome. A theory of mechanism and distinctions from the iridocorneal endothelial syndrome. Trans Am Ophthalmol Soc 1983;81:736. 9. Ritch R: Exfoliation syndrome and occludable angles. Trans Am Ophthalmol Soc 1994;92:845.
3. Blinder KJ, Friedman SM, Mames RN: Diabetic iris neovascularisation. Am J Ophthalmol 1995;120:393.
10. Lichter PR, Schaffer RN: Iris processes and glaucoma. Am J Ophthalmol 1970;70:905.
4. Schulze RR: Rubeosis iridis. Am J Ophthalmol, 1967 63:487. 5. Anderson DM, Morin JD, Hunter WS: Rubeosis iridis. Can J Ophthalmol, 1971;6:183.
11. Blanton FM: Anterior chamber angle recession and secondary glaucoma. A study of the after effects of traumatic hyphemas. Arch Ophthalmol 1964;72:39.
6. John T, Sassani JW, Eagle RC Jr: The myofibroblastic component of rubeosis iridis. Ophthalmology 1983;90:721.
12. Yanoff M: Glaucoma mechanisms in ocular malignant melamonas. Am J Ophthalmol 1970;70:898.
7. Nomura T: Pathology of the anterior chamber anglein diabetic neovascular glaucoma: Extension of corneal endothelium onto iris surface. Jpn J Ophthalmol 1983;27:193.
13. Chandler PA, Grant WM: Glaucoma, 2nd edition Philadelphia, Lea and Febiger, 1979. p 267
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Chapter 14
Sterilization of Gonioscopes
Gonioscopy is an invasive procedure. As the lens comes in contact with cornea and the tear film, it has the potential to cause infections and spread serological diseases. Various bacterial and viral infections can spread through infected gonioscopes, even epidemics of viral keratoconjunctivitis.1 Currently there is a concern regarding the spread of lethal viruses like the HIV and the Hepatitis B and C viruses among others.2,3,4 Hence sterilization and disinfection of gonioscopes between uses is imperative. Before performing gonioscopy, a meticulous history and a detailed ocular examination are of paramount importance. History concerning presence of symptoms suggestive of serological diseases and prolonged systemic disorder should be elicited. History of blood transfusions, organ transplants, renal dialysis and drug addiction should be sought. The eyes should be examined for the presence and evidence of any active infection. Presence of conjunctival hyperemia, mucopurulent discharge, matting of eyelashes, occult or evident globe perforation, history of recent ocular trauma, corneal epithelial defect, active herpes or local cellulitis would contraindicate performing a gonioscopy procedure.
■■Ideal sterlization method An ideal sterilization method should be as follows: 1. It should be effective against the common viruses and bacteria including adenoviruses, herpes virus, hepatitis virus and HIV. 2. The method should not cause wear and tear of the gonioscope. 3. Should be easy to clean off the contact area and should not harm the cornea. 4. Should be easy to carry out, practical and repeatable. The cleaning, disinfection and sterilization of the goniolenses should be done in a systematic manner. After removing the lens from the patient’s eye, it should be immediately rinsed with clean cold water. Then the lens surface should be cleaned with a cotton bud soaked in mild soap or detergent with circular motions. Again it is rinsed with cold clean water and dried with a non-linting cloth. After cleaning, the lens is disinfected. Disinfection is carried out using either glutaraldehyde or bleaching powder. The lens is soaked in 2% glutaraldehyde for at least 20 minutes or a 10% bleach solution (sodium hypochlorite) at 1 part bleach to 9 parts water for 10 minutes. The lens is then thoroughly rinsed with clean cold water and air dried. The gonioscope can also be wiped for 10 seconds with a
sterile swab soaked in 70% isopropyl alcohol or cleaned with 1:1000 merthiolate solution. Sterilization follows disinfection which is achieved by ethyelene oxide exposure (ETO). The sterilization of direct gonioscopes (Koeppe, Swan Jacob, etc.) used during surgery can be done with ethylene oxide gas sterilization. ETO is achieved by exposure at 56°C (130°F) for one hour.
■■Cleaning and sterilization: Points to remember 1. To avoid damage to the lens, do not exceed recom mended exposure time 2. Rinse lens thoroughly to remove disinfection solution 3. Never Steam Autoclave or Boil listed lenses 4. Never soak in Alcohol, Acetone or Other Solvents 5. Always use antibiotic eye drops after doing gonioscopy 6. Always check for epithelial defect after gonioscopy especially in first few cases and in patients with history of diabetes or other epithelial disorders.
■■Common Errors while performing Gonioscopy 1. Air bubble may obstruct the view of angle. If the bubble is small, tilt the lens to remove the bubble and if this is not possible, remove and reinsert the goniolens 2. Inadequate coupling fluid 3. Lack of elbow support makes it difficult to keep the hand still for continuous viewing during gonioscopy 4. Excessive pressure with Goldmann type lenses can lead to artifactual narrowing / distortion of the angle 5. Excessive pressure with Zeiss type goniolenses can cause Descemet’s folds and widely open a narrow angle 6. Pigmentation present anterior to or on the Schwalbe’s line may be confused as the trabecular meshwork unless the corneal wedge method is used to identify the angle structures 7. Blood in Schlemm’s canal can occur due to excessive pressure 8. Prolonged pressure can lead to corneal edema 9. Light of the slit lamp passing through the pupil can cause opening of an occludable angle due to papillary constriction, so dim illumination in short slit is a must when grading narrow angles.
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10. Excessive pressure with Goldmann type lens can cause false narrowing of angle 11. Gonioscopy is not a one time examination and must be repeated atleast once a year during the follow up of glaucoma patients as one can get progressive
narrowing of the angle with thickening or anterior displacement of the lens with age. 12. The operating microscope must be tilted to get an adequate view of the angle while doing direct gonioscopy with Koeppe type lenses in congenital glaucoma.
■■References 1. Buchler JW, Finton RJ, Goodman RA, Choi K, Hierholler JC, Sikes K, et al. Epidemic keratoconjunctivitis: report of an outbreak in an ophthalmology practice and recommendations for prevention. Inf Control 1984;5:390–94. 2. Fujikawa GS, Palestine AG, Nussenblatt RB, Salahuddin SZ, Masur H, Gallo RC. Isolation of lymphotropic virus type III from tears of a patient with AIDS. Lancet 1985;2:529–30.
3. Fujikawa LS, Salahuddin SZ, Abhilashi D, Palestine AG, Masur H, Nussenblatt RB, et al. HTLV-III in tears of AIDS patients. Ophthalmology 1986;93:1479–81. 4. Gastaud P, Bandraun CH, Ouzan D. Detection of HBS antigens, DNA polymerase activity and hepatitis B virus DNA in tears: relevance to hepatitis B transmission by tears. Br J Ophthalmol 1989;73:333–36.
Chapter 15
RetCam Gonioscopy
Gonioscopy is the current reference standard for assessing the anterior chamber angle (ACA). The advantages of gonioscopy include the ability to visualize a whole quadrant of the ACA at one time, the use of the corneal wedge to help identify landmarks in the angle such as Schwalbe’s line, and the ability to dynamically indent the angle and distinguish peripheral anterior synechiae (PAS) from appositional closure. Various grading schemes have been developed to categorize eyes on the basis of gonioscopic assessment of the ACA, but such schemes are based on subjective and at best semiquantitative assessments. However, factors such as the type of lens used, the technique used, and the skill of the observer affect the variability of gonioscopy findings. Documentation of gonioscopic findings is often poor, with most clinicians recording them in charts without images or photographic records. The RetCam, popularly known as the Eyecam, (Clarity Medical Systems, Pleasanton, CA, USA) is a new technology (Figure 15.1) originally designed to yield wide-field photographs of the pediatric fundus for the diagnosis and management of posterior segment diseases.1 With modifications in the optical technique and the inclusion of a 130 degree lens, the device can be used to visualize angle structures in a manner similar to direct gonioscopy. The hardware consists of a hand-held digital video camera connected fiberoptically to a light-emitting control unit and computer assembly. The operator controls focus, illumination, and the acquisition of images with a foot switch. Images are automatically saved to a computer hard drive. Alternatively, a short video stream can be captured, with still frames selected from the video and saved at the end of the imaging session. For imaging, patients are positioned supine and the lens probe is placed on a coupling gel without direct contact onto the cornea (Figure 15.2), minimizing alteration of angle configuration due to compression artifact and causing less discomfort than gonioscopy. To image a particular angle quadrant, the patient is instructed to look in the direction of that angle. The probe is positioned at the opposite limbus to the angle being photographed and light from the fiber optic probe is directed toward the angle of interest and then tilted downward, to bring the angle structures into view while minimizing pupillary constriction. The RetCam is thus a new and objective way of documenting angle configuration, using a photographic method similar to goniophotography. The images produced are easy for clinicians to interpret as the angle appears
Figure 15.1 RetCam
Figure 15.2 RetCam hand piece with 130 degrees lens with patient in supine position
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Gonioscopy: A Text and atlas
similar to what is seen during gonioscopy. Images recorded by the RetCam can be saved on a computer thus allowing comparisons to be made over time (Figure 15.3). Such “goniographic” documentation by RetCam allows for monitoring of angle changes over time, tracking of angle changes with disease progression as well as treatment effects and use as patient education tools. The RetCam can also help identify some etiologies of open angle glaucoma such as pigment dispersion syndrome, pseudoexfoliation syndrome and neovascular glaucoma, as it produces a high magnification, true color view of the structures within the iridocorneal angle. Perhaps the simplest yet most noticeable advantage of the Retcam technology over traditional gonioscopy relates to patient comfort. Unlike gonioscopy, the Retcam is applied lightly to the limbus and with the patient in a semi-recumbent position, which limits the patient’s natural reflex to move during an examination. The lens probe is placed on a coupling gel without direct contact onto the cornea, eliminating the concern of compression
artifact. Light from the fiber optic probe is directed into the angle as opposed to the pupil to reduce light artifact. Lastly, a trained ophthalmic technician can acquire images for each of the Retcam applications. Then, the images can be either evaluated locally or sent remotely for evaluation by a clinician. The imaging system is designed to enable tele-ophthalmology applications via the Internet. In a study comparing these two modalities, Perera et al. found that the agreement between RetCam and gonioscopy in detecting closed quadrants in the superior, inferior, nasal and temporal quadrants based on AC1 statistics was 0.73, 0.75, 0.76 and 0.72, respectively. RetCam had 76% sensitivity and 81% specificity for detecting eyes with angle closure using the two-quadrant definition of angle closure to categorize each eye.2 Although the RetCam is as yet unable to provide quantitative measurements of anterior chamber depth like the AS-OCT or UBM, it provides a 360 degree visualization of the entire ACA compared with the ASOCT and UBM, which provide only cross-sectional views.
Figure15.3 RetCam gonioscopy showing high definition images of the angle
RetCam Gonioscopy
The device has some limitation:2 imaging of the ACA using RetCam takes longer than gonioscopy (about 5–10 min per eye). The device is more expensive than gonioscopy and additional space is required for supine examination. It is not known if supine positioning would widen the angle due to the effect of gravity on the lens-iris diaphragm. The light source from the RetCam, delivered via a fiber optic cable, may cause pupil constriction, artificially altering ACA
configuration. Unlike with dynamic gonioscopy, it is difficult to discern the presence of PAS due to the inability to indent the angle. Similarly, determination of iris configuration is difficult with the two-dimensional RetCam images. Reproducibility may also be compromised as, with repeat imaging, each photograph may be slightly rotated and images may not be obtained over the exact same location, unless certain landmarks on the iris are used as anchors.
■■References 1. Calafati J, Naqi A, Ahmed I. Ocular Surgery News. US ed. Digital imaging system an alternative to traditional process, 2009.
2. Quek DTL, Nongpiur ME, Perera SA, and Aung T. Angle imaging: Advances and challenges. Indian J Ophthalmol. 2011;59(Suppl1):S69–S75.
91
Gonioscopy Atlas
Open Angle Open angle as seen on gonioscopy
Open angle on gonioscopy high magnification
96
GOniOscOpy: A TexT And ATlAs
Open angle on gonioscopy with angle structures visible
Open angle on gonioscopy
Wide open angle on gonioscopy
Gonioscopy Atlas
Myopia Open angle in myopia with pigmentation
Wide open angle in myopia
97
98
GOniOscOpy: A TexT And ATlAs
Angle Closure A closed angle
synechial angle closure
Gonioscopy Atlas
Closed Angle Opening on Manipulation Angle structures not visible in gonioscopy
same angle opening on manipulation
99
100
GOniOscOpy: A TexT And ATlAs
Areas of synechiae in angle closure
closed angle in pAcG
closed angle with pigmentation
Gonioscopy Atlas
Goniosynechiae
Apex of corneal wedge not visible in a closed angle
Occludable angle with a steep iris configuration
101
102
GOniOscOpy: A TexT And ATlAs
Occludable angle
central goniosynechiae
Gonioscopy Atlas
Anterior Iris Insertion Juvenile Glaucoma with anterior insertion of iris
Multiple iris processes seen in JOAG
103
104
GOniOscOpy: A TexT And ATlAs
Angle Recession Angle recession lateral view
Angle recession
Gonioscopy Atlas
Wide ciliary body band in angle recession
105
106
GOniOscOpy: A TexT And ATlAs
Aniridia Rudimentary iris stump in aniridia
Atrophic ciliary processes in aniridia
Gonioscopy Atlas
Aniridia with a small iris stump
small iris stump with atrophic ciliary processes in aniridia
107
108
GOniOscOpy: A TexT And ATlAs
Anterior Chamber Intraocular Lens Kelman multiflex anterior chamber intraocular lens in angle
Kelman multiflex Anterior chamber intraocular lens in superior angle near the peripheral iridectomy
Gonioscopy Atlas
Axenfeld-Rieger Syndrome iris attached to peripheral part of cornea in Axenfeld-Rieger syndrome
Anterior synechiae in Axenfeld-Rieger syndrome
109
110
GOniOscOpy: A TexT And ATlAs
Rieger syndrome synechiae
Broad and anterior synechiae in Axenfeld-Rieger syndrome
synechiae in Axenfeld-Rieger syndrome
Gonioscopy Atlas
prominent schwalbe’s line with iris strands
111
112
GOniOscOpy: A TexT And ATlAs
Blood in the Angle Resolving Hyphema obscuring the angle
Blood in angle low magnification
Gonioscopy Atlas
Ciliary Body Melanoma ciliary body melanoma eroding into the angle
ciliary body tumor in the inferior angle
113
114
GOniOscOpy: A TexT And ATlAs
ciliary body tumour with prominent blood vessels
Gonioscopy Atlas
Corneal Wedge corneal wedge
identifying schwalbe’s line with corneal wedge
115
116
GOniOscOpy: A TexT And ATlAs
Cotton Fibers in the Angle cotton fibers in the angle high magnification
cotton fibers in the angle
Gonioscopy Atlas
Cyclodialysis post-traumatic cyclodialysis cleft
cyclodialysis in inferior angle
117
118
GOniOscOpy: A TexT And ATlAs
cyclodialysis cleft
post-traumatic cyclodialysis
Gonioscopy Atlas
Express Implant express implant in angle overlying peripheral iridectomy
express implant in angle
119
120
GOniOscOpy: A TexT And ATlAs
implant in angle in high magnification
implant in angle
Gonioscopy Atlas
Fibrous Ingrowth Fibrous ingrowth with broken iOl haptic
121
122
GOniOscOpy: A TexT And ATlAs
Foreign Body in the Angle Foreign body in angle high magnification
Foreign body in angle
Gonioscopy Atlas
Goniosynechiae Goniosynechiae with iris adherent to trabecular meshwork
Goniosynechiae
123
124
GOniOscOpy: A TexT And ATlAs
Haptic of PC IOL in Angle through Iridectomy Haptic of intraocular lens in angle coming through peripheral iridectomy high magnification
Haptic of intraocular lens in angle coming through peripheral iridectomy
Gonioscopy Atlas
Iridodialysis post-traumatic irididoalysis high magnification
post-traumatic iridodialysis
125
126
GOniOscOpy: A TexT And ATlAs
Irido-fundal Coloboma irido-fundal coloboma
View of peripheral iris in typical coloboma
Gonioscopy Atlas
Iris Adherent to Cataract Surgical Wound iris adherent to incision
iris incarcerated in surgical wound with visible nylon suture
127
128
GOniOscOpy: A TexT And ATlAs
Iris Bombe closed angle with iris bombe
slit view of closed angle in iris bombe
Gonioscopy Atlas
Iris PE Cyst Causing Segmental Angle Closure iris pigment epithelial cyst tenting the iris
segmental angle closure in inferior angle
129
130
GOniOscOpy: A TexT And ATlAs
Kayser–Fleischer Ring KF ring seen in Wilson’s disease
KF ring pigment seen anterior to schwalbe’s line
Gonioscopy Atlas
Neovascularization of Angle neovascularization of angle causing synechial closure of angle
new vessel seen in superior angle
131
132
GOniOscOpy: A TexT And ATlAs
neovascularization of the angle
new vessels in superior angle
new vessels in the angle
Gonioscopy Atlas
Ocular Ischemic Syndrome closed angle in ocular ischemic syndrome
secondary angle closure in ocular ischemic syndrome
133
134
GOniOscOpy: A TexT And ATlAs
Pigment Dispersion Syndrome concave iris configuration in pigment dispersion syndrome
Heavily pigmented angle in pigment dispersion syndrome high magnification
Gonioscopy Atlas
Heavily pigmented angle in pigment dispersion syndrome
Muscara line like pigmentation in pigment dispersion glaucoma
pigmented angle in pigment dispersion syndrome
135
136
GOniOscOpy: A TexT And ATlAs
sampaolesi line
Magnified view of pigment band over trabecular meshwork
Gonioscopy Atlas
Plateau Iris Configuration with Double Hump Pattern plateau iris configuration double hump pattern
plateau iris configuration
137
138
GOniOscOpy: A TexT And ATlAs
Post Cataract Surgery Gonioscopy cataract surgical wound with suture
continuous suturing of corneoscleral incision
Gonioscopy Atlas
Post Surgical Angle Pigmentation irregular angle pigmentation post surgery
pigment clumps in the angle
139
140
GOniOscOpy: A TexT And ATlAs
irregular patchy angle pigment post surgery
post cataract surgery angle pigmentation
Gonioscopy Atlas
Post-traumatic Iridodialysis with Central PAS iridodialysis with central synechiae high magnification
iridodialysis with central synechiae
141
142
GOniOscOpy: A TexT And ATlAs
Post-traumatic Angle Pigmentation dense and diffuse angle pigmentation in a case of blunt trauma with areas of synechiae
post-trauma pigmentation of angle
Gonioscopy Atlas
post-traumatic synechiae in angle
View of ciliary body with a cyclodialysis cleft on the left side
143
144
GOniOscOpy: A TexT And ATlAs
Prominent Iris Processes Few prominent iris processes
prominent iris processes high magnification
Gonioscopy Atlas
prominent iris processes in juvenile open angle glaucoma
prominent iris processes
145
146
GOniOscOpy: A TexT And ATlAs
Prominent Schwalbe’s line Anteriorly placed prominent schwalbe’s line
pigmentation in area of schwalbe’s line
Gonioscopy Atlas
Band like schwalbe’s line at apex of corneal wedge
pigments and synechiae in schwalbe’s line
prominent schwalbe’s line high magnification
147
148
GOniOscOpy: A TexT And ATlAs
prominent schwalbe’s line with iris processes
prominent schwalbe’s line
synechiae to schwalbe’s line
Gonioscopy Atlas
Pseudophakia with Glaucoma Haptic of posterior chamber intraocular lens in angle with pigmentation causing secondary glaucoma
Haptic of posterior chamber intraocular lens in angle with pigmentation
149
150
GOniOscOpy: A TexT And ATlAs
pseudophakic glaucoma haptic of posterior chamber intraocular lens in angle with pigmentation
Haptic of posterior chamber iOl in angle
Gonioscopy Atlas
Pseudophakia with Glaucoma with AC IOL pseudophakic angle closure glaucoma with Ac iOl
pseudophakic glaucoma with synechial angle closure and pigment clumps
151
152
GOniOscOpy: A TexT And ATlAs
secondary angle closure due to Ac iOl haptic
iris wrapped around Ac iOl haptic
Vitreous and hyphema in angle in pseudophakia
Gonioscopy Atlas
Pseudotrabecular Meshwork in a Closed Angle pseudotrabecular meshwork in closed angle low magnification
Apex of corneal wedge posterior to pigmented line
153
154
GOniOscOpy: A TexT And ATlAs
Sarcoidosis Nodules in the Angle sarcoid nodule in angle
inflammatory nodules visible in inferior angle
Gonioscopy Atlas
Secondary Angle Closure due to High Vaulted ICL secondary angle closure due to high vault of implantable collamer lens
secondary glaucoma due to high vault of implantable collamer lens
155
156
GOniOscOpy: A TexT And ATlAs
Sentinel Synechiae sentinel synechiae in uveitic glaucoma
sentinel synechiae
Gonioscopy Atlas
Silicone Oil emulsified silicone oil and silicone oil bubble
emulsified silicone oil
157
158
GOniOscOpy: A TexT And ATlAs
Trabeculectomy Ostium closed ostium
Filtering ostium in trabeculectomy
Gonioscopy Atlas
iris Around Ostium
iris blocking the ostium with releasble sutures seen in high magnification
iris blocking the ostium with releasble sutures seen
159
160
GOniOscOpy: A TexT And ATlAs
iris stump blocking trabeculectomy ostium
Ostium blocked with iris tissue
Ostium blocked with iris
Gonioscopy Atlas
patent trabeculectomy ostium
Ostium visible as a crater in the sclera
Ostium with releasable sutures
161
162
GOniOscOpy: A TexT And ATlAs
Uveitic Glaucoma closed angle due to synechiae in uveitis
peripheral anterior synechiae in uveitis
Gonioscopy Atlas
Multiple synechiae in inferior angle
Broad based synechaie
Multiple broad based synechaie
163
164
GOniOscOpy: A TexT And ATlAs
Vitreous Strands in the Angle Gonioscopy showing vitreous in angle
Vitreous strand bridging the angle
Gonioscopy Atlas
Vitreous in superior angle
Vitreous strand in angle
165
166
GOniOscOpy: A TexT And ATlAs
View of Ciliary Body and Peripheral Retina ciliary body
ciliary processes and peripheral retina
Gonioscopy Atlas
Ahmed Glaucoma Valve Ahmed Glaucoma Valve blocked with iris
Ahmed Glaucoma Valve in angle
167
168
GOniOscOpy: A TexT And ATlAs
Ahmed Glaucoma Valve in superior angle
Index Note: Page numbers followed by f refer to figure and t refer to table
■■ A Ahmed glaucoma valve 84f, 167 blocked with iris 167 in angle 84f, 167 in superior angle 168 Anatomy of open angle 49 Angle causing synechial closure of angle 131 closure 98 glaucoma stage 59 opening on manipulation 24f, 25f pigmentation 50f recession 41, 69f, 70f, 140 Angular width of angle recess 37, 38 Aniridia 54, 56f, 106, 107 Anterior chamber angle 89 intraocular lens 108 insertion of iris 41 iris insertion 103 pigmentation in closed angle 46f Anteriorly placed prominent Schwalbe’s line 146 Apex of corneal wedge in open angle 30f Aphakic and pseudophakic glaucoma 76 glaucoma 77f Atrophic ciliary processes in aniridia 106 Axenfeld anomaly 54, 54f with glaucoma 54 Axenfeld-Rieger syndrome 54, 109, 109f, 110
■■ B Barkan lens 11 Biometric gonioscopy 23, 27 Bleeding spots 41 Blood in angle 112 low magnification 112 Schlemm’s canal 41
■■ C Carotid artery occlusive disease 60 Cataract surgical wound 127, 138 Central goniosynechiae 102 Chandler syndrome 62 variant of ICE syndrome 61f Chronic primary angle closure glaucoma 43f, 46
Ciliary body 166 and peripheral retina 166 band 29, 31, 33f, 49 in angle recession 105 melanoma 113 tumor 75f, 76f in inferior angle 113 with prominent blood vessels 114 Closed angle 98, 162 in iris cyst 74f in ocular ischemic syndrome 133 in PACG 45f, 100 in primary position 24f opening on manipulation 99 with iris bombe 128 with neovascularization of iris 60f with pigmentation 100 Closed ostium 158 Cogan–Reese syndrome 61f, 62 Collagen vascular disorders 8 Concave iris configuration 31f in pigment dispersion syndrome 134 Congenital and developmental glaucoma 53 Conjunctivitis 8 Contact lenses for gonioscopy 11t Continuous suturing of corneoscleral incision 138 Contour of iris 30 Convex iris configuration 31f, 46f Convexity of iris 35 Corneal epithelial defects 8 wedge 115, 147 Cotton fibers in angle 116 high magnification 116 Cyclodialysis 41, 117 cleft 118 in inferior angle 117 Cysts 41
■■ D Degree of angle closure 35 trabecular pigmentation 29 Dense and diffuse angle pigmentation 142 limbus 8 Descemet’s membrane 41 Determination of angle width 35 Diameter of contact 15 Direct gonioscopy 11, 12f, 53f Dynamic gonioscopy 15
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Gonioscopy: A Text and atlas
■■ E Elevated episcleral venous pressure induced glaucoma 82 Emulsified silicone oil 157 Essential iris atrophy 62 Evaluation of functional status of angle 35 Excimer laser trabeculotomy 7 Exfoliation syndrome 33 Express implant in angle 119 overlying peripheral iridectomy 119
■■ F Father of gonioscopy 3 Fibrous ingrowth 41, 121 Fine iridocorneal adhesion in Axenfeld anomaly 55f Flecks of exfoliation 64 Foreign body in angle 73f, 122 high magnification 122
■■ G Glaucoma after anterior segment surgery 76 after posterior segment surgery 81 drainage devices 84 Goldmann lens 20f single 15f, 16 mirror 11, 15 six mirror lens 15f three mirror 15, 15f triple mirror lens 16 type gonioscopes 26 lenses 23 Gonioplasty 7 Gonioscopy 3t, 7t, 8t, 36, 53f, 57f, 84f, 85f, 87, 164 grading systems 37 on slit lamp biomicroscope 20f with corneal lenses 21 with scleral lenses 19 Goniosynechiae 75, 101, 123 in angle 44f Goniotomy 7
Inflammatory nodule in angle 68f Insertion of Goldmann lens 19f Posner corneal gonioscope 21f Internal sclera opening in trabeculectomy 82f, 83 Iridocorneal adhesion 41 in Axenfeld–Rieger syndrome 55f in Cogan–Reese syndrome 62f in ICE 61f endothelial syndrome 41, 60, 60f Iridodialysis 41, 125 with central synechiae 141 Irido-fundal coloboma 57, 57f, 126 Iris bombe 128 configuration 37 holes 54 nevus 62 pigment epithelial cyst tenting iris 129 processes 30, 41 stump blocking trabeculectomy ostium 160 Irregular angle pigmentation post surgery 139 patchy angle pigment post surgery 140 Irrigation 21, 22
■■ J Juvenile glaucoma with anterior insertion of iris 103 open angle glaucoma 50, 50f
■■ K Kayser–Fleischer ring 8f, 130 Kelman multiflex anterior chamber intraocular lens 108 Keratitis 8 Koeppe’s goniolenses 12f lens 11, 12f in congenital glaucoma 53f Krukenberg spindle 64, 64f
■■ L ■■ H Haptic of intraocular lens 124 posterior chamber intraocular lens in angle with pigmentation 149, 150 High insertion of iris 50f Hyphema 8, 41 Hypopyon 41
■■ I Implantable Collamer lens 155 Indentation gonioscopy 7, 18, 23, 26, 27f, 47 Indications of gonioscopy 7 Indirect gonioscopy 11, 12f, 14
Large goniosynechiae in angle 44f Laser goniophotocoagulation 7 trabeculoplasty 7 Lens induced glaucomas 62 uveitis 62 insertion 19, 21 particle glaucoma 62 removal 21, 22 Level of iris insertion 29, 37 Limbal ocular surface squamous neoplasia 75f Limbus corneal scars 8 Low slit illumination 41 Lower lid margin 20f
Index ■■ M Malignant glaucoma 76 Manipulation 19, 22 Manipulative gonioscopy 23 Mascara line pigmentation 66f Mirror angulation 15 height 15 Multiple broad based synechiae 163 synechiae in inferior angle 163 Muscara line like pigmentation in pigment dispersion glaucoma 135 Myopia 97
■■ N Nd-Yag laser after deep sclerectomy 7 Neovascular glaucoma 59, 60f Neovascularization of angle 131, 132 Non-pigmented trabecular meshwork 29 Normal anterior chamber angle 32f blood vessels 34 gonioscopic anatomy 29
■■ O Occludable angle 43, 45f, 101, 102 Ocular goniolenses 17t ischemic syndrome 60f, 133 Koeppe lens 17 Open angle glaucoma stage 59 in myopia with pigmentation 97 on gonioscopy 32f, 33, 96 high magnification 95 in high myopia 33 Ostium blocked with iris 160 in trabeculectomy 82f
■■ P Patent trabeculectomy ostium 161 Pediatric surgical goniolens 13f Periodic gonioscopy 47 Peripheral and mid peripheral iridocorneal adhesions 56f anterior synechiae 37, 43, 45f, 46f, 89 in uveitic glaucoma 67f in uveitis 162 with irregular angle pigmentation 67f iridectomy 124 iridocorneal adhesion in Axenfeld-Rieger syndrome 55f, 56f Phacomorphic glaucoma 63 Phacotopic glaucoma 63 Phakic IOL causing angle closure 78f Pigment clumps in angle 139 dispersion syndrome 33, 64f-66f, 134
Pigmented angle in pigment dispersion syndrome 135 trabecular meshwork 29 Placement of posner lens 21f Plateau iris configuration 47, 47f, 137 Posner goniolens 14f lens 16 Postacute attack of angle closure 44f Postcataract surgery angle pigmentation 140 gonioscopy 138 Posterior embryotoxon on gonioscopy in Axenfeld anomaly 55f Postextracapsular cataract extraction synechiae 78f Postpenetrating keratoplasty glaucoma 79 Postsurgical angle pigmentation 139 evaluation of anterior chamber angle 82 Post-trauma pigmentation of angle 142 Post-traumatic angle pigmentation 142 recession and cyclodialysis 71f cyclodialysis 117, 118 glaucoma 66, 72f iridodialysis 72, 125 iris cyst 74f synechiae in angle 143 Preglaucoma stage 59 Pressure or dynamic gonioscopy 26 Prevalence of neovascular glaucoma 59 Primary angle closure disease 43 glaucoma 43 congenital glaucoma 53 open angle glaucoma 49 Principle of gonioscopy 5, 5f Progressive iris atrophy 61, 61f Proliferative diabetic retinopathy 35f Prominent iris processes 57f, 144, 145 Schwalbe’s line 11, 34, 35f, 146-148 Pseudoexfoliation syndrome 63, 63f, 64f Pseudophakia 77f with glaucoma 149, 151 Pseudophakic angle closure glaucoma with AC IOL 151 glaucoma 78, 80f haptic of posterior chamber intraocular lens 150 Pseudotrabecular meshwork 68f in closed angle 153 low magnification 153 Pupillary size 35
■■ R Radius of curvature 15 Reopening of blocked trabeculectomy opening 7 RetCam gonioscopy 89, 90f Retrodisplacement of iris root 75 Rieger anomaly 54, 56, 56f, 110 Ritch trabeculoplasty lens 11 Root of iris 49
171
172
Gonioscopy: A Text and atlas
RPC classification 37, 38 Rudimentary iris stump in aniridia 106
■■ S Sampaolesi’s line 64, 65f, 136 in pigment dispersion syndrome 65f Sarcoid 68f nodule in angle 154 Sarcoidosis nodules in angle 154 Scheie system 38, 38t Schlemm’s canal 19, 29, 33 Schwalbe’s line 27, 29, 29f, 32f, 33f, 34, 35f, 37, 44f, 49, 50, 55f, 61f, 64, 115f, 130, 146, 148, 147 Scleral spur 29, 31, 49, 50 type lenses 22 Secondary angle closure 63f in ocular ischemic syndrome 133 Segmental angle closure 46f, 129f in inferior angle 129 Sentinel synechaie 156 in uveitic glaucoma 156 Shaffer grading of angle width 37f system 37, 37t Silicone oil 157 bubble 157 Site of iris insertion 30 Size of rim 15 Slit lamp gonioscopy technique 19 Spaeth grading of angle width 38f peripheral iris curvature 38f site of iris insertion 38f Spontaneous hyphemas 59 Square configuration 21 Sterilization of gonioscopes 87 Subluxation of lens 63f Sussman type goniolens 14f Swan Jacob lens 11, 13f, 53f Synechiae in Axenfeld-Rieger syndrome 110 case of post-traumatic glaucoma 70, 71 Synechial angle closure 98 closure 25f
■■ T Three finger technique 19 Total internal reflection in eye 5f Trabecular meshwork 33, 33f, 49, 50 pigmentation 38 Trabeculectomy 82f, 83f ostium 158 Two finger technique 19 Type of lens 15
■■ U Uveitic glaucoma 65, 67f, 68f, 162 Uveitis 68, 68f Vascular endothelial growth factor 59
■■ V Vitreous strand bridging angle 164 in angle 164 wick syndrome 77f Volk goniolenses 16t
■■ W Wide open angle in myopia 97 on gonioscopy 96 Wilson’s disease 130 on gonioscopy 8f on slit lamp examination 8f Wrap around iris 54f
■■ Z Zeiss four mirror 11, 15 lens 16, 21
