Jurnal Pterygium [PDF]

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DOI: 10.18410/jebmh/2015/832



ORIGINAL ARTICLE ASTIGMATISM IN PRIMARY PTERYGIUM AND ITS EFFECT ON VISUAL ACUITY Devika P1, Lakshmi K. S2, Rajani K3, Sudhir Hegde4, Asha Achar5, Ajay Kudva6 HOW TO CITE THIS ARTICLE: Devika P, Lakshmi K. S, Rajani K, Sudhir Hegde, Asha Achar, Ajay Kudva. “Astigmatism in Primary Pterygium and its Effect on Visual Acuity”. Journal of Evidence based Medicine and Healthcare; Volume 2, Issue 38, September 21, 2015; Page: 6036-6040, DOI: 10.18410/jebmh/2015/832



ABSTRACT: BACKGROUND: Pterygium is a fairly common condition in a tropical country like India with average incidence being 5.2%. Surgery being offered as a treatment for pterygium does not, at present, have a universally accepted indication based on the size. This study was done to make an attempt to define the indication for surgical exicision of pterygium. AIMS: To find out an association between increasing size of pterygium and degree of induced corneal astigmatism and to assess if corneal astigmatism induced by pterygium affects best corrected visual acuity (BCVA) and thus making it an indication for pterygium excision surgery. SETTINGS AND DESIGN: Hospital Out Patient Department (OPD) based prospective clinical cross sectional study on patients with unilateral pterygium. METHODS AND MATERIAL: 33 patients were included in this study who had unilateral pterygium of varying sizes. Evaluation was done using slit-lamp beam for size of pterygium in millimetre from the limbus, ketatometry using Bausch and Lomb keratometer, autorefractometer objective refraction readings, visual acuity and BCVA using Snellens chart. STATISTICAL ANALYSIS USED: Chi-square-test, Karl-Pearson correlation coefficient, Kruskal-Wallis-co-efficient using SPSS statistics 22.0. RESULTS: 33 people having unilateral pterygium were divided into three groups on the basis of size of the pterygium- ≤2mm, 2.1-3mm, >3mm. The co-relation coefficient between the astigmatism induced to BCVA was maximum for the 3rd group with pterygium size >3mm and was statistically significant. CONCLUSION: Pterygium induces ‘with the rule’ astigmatism. Surgery is indicated in patients of pterygium size >3mm as the astigmatism induced affects the BCVA. KEYWORDS: Pterygium, Unilateral, Astigmatism, BCVA. INTRODUCTION: Clinically, pterygia are fleshy, vascularized, often triangular formations of tissue that extend across the limbus and onto the cornea.[1] The histopathologic hallmark of pterygia and pingueculae is elastotic degeneration of the collagen of the substantiapropria[2] Pterygia are most common in southern latitudes and typically occur in patients who work outdoors.[1,3] Pterygium is commonly seen in India, a part of the “pterygium belt” described by Cameron.[4] Pterygium leads to a considerable effect on corneal refractive status which has been previously measured in various studies by refraction,[5,6] keratometry[7] and corneal topography.[8,9,10,11,12,13] In the present study, we assess the relationship between pterygium size and induced corneal astigmatism and to observe whether astigmatism secondary to pterygium is an indication for surgery. MATERIALS AND METHODS: 33 patients of unilateral pterygium were included in the study. The normal eye without pterygium had no abnormalities and had best corrected visual acuity of J of Evidence Based Med & Hlthcare, pISSN- 2349-2562, eISSN- 2349-2570/ Vol. 2/Issue 38/Sept. 21, 2015 Page 6036



DOI: 10.18410/jebmh/2015/832



ORIGINAL ARTICLE 6/6 was taken as control to compare with the other eye having pterygium for change in astigmatism pattern in relation to the size of pterygium. Evaluation of pterygium was done using.  Slit-lamp beam measurements of size of pterygium (in millimeters) from the limbus.  Ketatometry using Bausch and lomb keratometer.  Auto refractometer objective refraction readings.  Visual acuity and best corrected visual acuity using snellens chart. RESULTS: in our study of the 33 people having unilateral pterygium, of mean age 42.58 years±11.096 years, 17 (51.5%) were males and 16 (48.5%) were females. The total subjects (n=33) was divided into 3 groups on the basis of size of the pterygium



≤2 2.1-3 >3



Frequency 13 8 12



Percent 39.4 24.2 36.4



Table 1: Frequency distribution of subjects on the basis of size of petrygium In 19 subjects (57.6%), right eye was affected and in 14(42.4%), left eye was affected. 32 patients had nasal pterygium and 1 had temporal pterygium. In our study, pterygium induced with the rule astigmatism in all patients. Mean of BCVA Standard deviation in BCVA Group 1- 3mm 0.682 0.16 Table 2: Size of the pterygium in co-relation with BCVA This table indicates that as the size of pterygium goes on increasing, the mean BCVA keeps on decreasing. Size of pterygium BCVA 6/6 BCVA 3mm as compared to those with 3mm, probability of BCVA being 3mm. DISCUSSION: Pterygium is a worldwide disease which is particularly common in tropical and sub-tropical regions.[14] Through its astigmatic impact it is often the cause of several subjective visual complaints, which include decreased visual acuity or visual aberrations such as glare or diplopia.[15] The automated keratometer is readily available to the Ophthalmologist as compared to the other instruments. It’s utility in analyzing the astigmatic effects of pterygium and then deciding whether to excise it or not is very convenient. The type of astigmatism that pterygium causes in the majority of cases is with the rule. This astigmatism occurs by mechanical pull which causes localized flattening of horizontal meridian of the cornea occurring up to the leading apex of the pterygium.[16] However, pterygium also induces against the rule and oblique astigmatism.[3] LIN and STERN found asignificant correlation between the pterygium size and corneal astigmatism, they reported that pterygium induces significant degrees of corneal astigmatism once it exceeded (>45%) of the radius of the cornea or within (3.2) mm of visual axis.[15] The exact mechanism of flattening is not clear, it is thought that astigmatism is mainly caused by the formation of tear meniscus between the corneal apex and the elevated pterygium causing apparent flattening of the normal corneal curvature. [16,17] A study done by Dr. Qasim Kadhim Farhood et al in Iraq showed that Pterygium induces with the rule astigmatism and often leads to visual impairment more so if pterygium is more than 2 mm size from the limbus and they suggested pterygiumexicision surgery for the same.[18]



J of Evidence Based Med & Hlthcare, pISSN- 2349-2562, eISSN- 2349-2570/ Vol. 2/Issue 38/Sept. 21, 2015 Page 6038



DOI: 10.18410/jebmh/2015/832



ORIGINAL ARTICLE Another study by Rahim Avisar et al from Israel found that pterygium induced visually significant with the rule astigmatism if >1.1mm in size and suggested surgical exicision of pterygium if >1mm in size.[19] In this study, all our patients had a change towards with the rule astigmatism (100%) in comparison with the normal eye without pterygium i.e, in 8 patients against the rule astigmatism that decreased, 5 patients had with the rule astigmatism that increased and 20 patients had no astigmatism that became with the rule astigmatism. Our study showed that clinically significant astigmatism (astigmatism causing visual impairment which could be corrected by glasses) is induced by pterygium of more than 3 mm size from the limbus, this tends to increase significantly with increasing size of the pterygium and in turn leads to impairment of vision. In other words, the extension of pterygium is significantly correlated with the degree of corneal astigmatism with higher percentage of with the rule astigmatism, therefore surgical intervention of pterygium is indicated when the size of the lesion is more than 3 mm from the limbus. CONCLUSION: Nasal pterygium is more common when compared to temporal pterygium. Pterygium induces with the rule astigmatism. Surgery for pterygium is indicated in patients of pterygium size >3mm as the astigmatism induced affects the BCVA to a maximum extent. REFERENCES: 1. Eagle RC: Eye pathology: an atlas and basic text. Philadelphia, WB Saunders, 1999: 47, 7273. 2. Cameron ME: Histology of pterygium: an electron microscopic study. Br J Ophthalmol, 1983. 67: 604-608. 3. William Tasman, Edward A. Jaeger. Duane’s ophthalmology. London:Lippincott Williams & Wilkins;2007. 4. Demartini DR, Vastine DW. Pterygium. In: Abbott RL, editor. Surgical interventions Corneal and External diseases. Grune and Straton: Orlando, USA; 1987. p. 141. 5. Fong KS, Balakrishnan V, Chee SP, Tan DT. Refractive change following pterygium surgery. CLAO J 1998; 24: 115-7. 6. Maheshwari S. Effect of pterygium excision on pterygium-induced astigmatism. Indian J Ophthalmol 2003; 51: 187-8. 7. Hansen A, Norn M. Astigmatism and surface phenomena in pterygium. ActaOphthalmol (Copenh) 1980; 58: 174-81. 8. Lin A, Stern G. Correlation between pterygium size and induced corneal astigmatism. Cornea 1998; 17: 28-30. 9. Stern G, Lin A. Effect of pterygium excision on induced corneal topographic abnormalities. Cornea 1998; 17: 23-7. 10. Tomidokoro A, Miyata K, Sakaguchi Y, Samejima T, Tokunaga T, Oshika T. Effects of pterygium on corneal spherical power and astigmatism. Ophthalmology 2000; 107: 156871.



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DOI: 10.18410/jebmh/2015/832



ORIGINAL ARTICLE 11. Cinal A, Yasar T, Demirok A, Topuz H. The effect of pterygium surgery on corneal topography. Ophthalmic Surg Lasers 2001; 32: 35-40. 12. Yagmar M, Altan A, Ozcan MD, Sari S, Ersoz RT. Visual acuity and corneal topographic changes related with pterygium surgery. J Refract Surg 2005; 21: 166-70. 13. Oldenburg JB, Garbus J, McDonnell JM, McDonnell PJ. Conjunctival pterygia. Mechanism of corneal topographic changes. Cornea 1990; 9: 200-4. 14. Kamil Z, Bokhari SA, Rizwi F. Comparison of conjunctival autograft and intraoperative application of mitomycin-C in the treatment of primary pterygium. Pak J Ophthalmol 2011; 27: 221-5. 15. Jaffar S, Dukht U, Rizvi F. Impact of pterygium size on corneal topography. RMJ 2009; 34:145-7. 16. Lin A, Stern GA. Correlation between pterygium size and induced corneal astigmatism. Cornea 1997; 17: 22-7. 17. Salih PM, Sharif AF. Analysis of pterygium size and induced corneal astigmatism. Cornea 2008; 27: 434-8. 18. Qasim Kadhim Farhood et al. Pterygium and induced astigmatism. KufaMed. Journal 2012; 15; 341-4. 19. Rahim Avisar et al. Pterygium induced corneal astigmatism. IMAJ 2000; 2: 14-5.



AUTHORS: 1. Devika P. 2. Lakshmi K. S. 3. Rajani K. 4. Sudhir Hegde 5. Asha Achar 6. Ajay Kudva PARTICULARS OF CONTRIBUTORS: 1. Consultant, Department of Ophthalmology, AJ Institute of Medical Sciences, Mangalore. 2. Junior Resident, Department of Ophthalmology, AJ Institute of Medical Sciences, Mangalore. 3. Associate Professor, Department of Ophthalmology, AJ Institute of Medical Sciences, Mangalore. 4. Professor & HOD, Department of Ophthalmology, AJ Institute of Medical Sciences, Mangalore.



5. Assistant Professor, Department of Ophthalmology, AJ Institute of Medical Sciences, Mangalore. 6. Associate Professor, Department of Ophthalmology, AJ Institute of Medical Sciences, Mangalore. NAME ADDRESS EMAIL ID OF THE CORRESPONDING AUTHOR: Dr. Lakshmi K. S, # 450, 6th Floor, Staff Quarters, AJ Institute of Medical Sciences, Kuntikana, Mangalore-575004. E-mail: [email protected] Date Date Date Date



of of of of



Submission: 05/08/2015. Peer Review: 06/08/2015. Acceptance: 08/09/2015. Publishing: 18/09/2015.



J of Evidence Based Med & Hlthcare, pISSN- 2349-2562, eISSN- 2349-2570/ Vol. 2/Issue 38/Sept. 21, 2015 Page 6040