Refractive and Corneal Topographic Changes after Primary Pterygium Excision and Comparison between Auto Grafting and using Mitomycin c.

Abstract

Background: Pterygium is a degenerative disorder of the conjunctiva. Horizontal flattening is the most frequent corneal topographic change in eyes with pterygia. Successful pterygium surgery significantly improves the refraction and manages the flattening effect of pterygium on corneal topography. Objective: Evaluate refractive and topographic changes occurring in cornea after pterygium surgery and differentiate between autografting and mitomycin c . Patients and Methods: A cross sectional observational study designed to analyze data of 30 eyes with pterygia arranged into 2 groups: (Group a: patients managed with auto grafting, Group b: patients managed with MMC) 15 eyes in each group. The study was performed in the time interval between January 2019 and October 2019. Results: the study showed improvement of spherical and cylindrical powers after surgery. Spherical corneal power showed significant change from 2.83 ± 2.11 SD to 1.45 ± 1.66 SD. Also cylindrical power showed significant reduction from -4.82 ± 3.71 SD to -2.55 ± 2.85 SD. There was significant improvement in the K readings and anterior corneal astigmatism. Mean improvement in K1 was noted from 39.19 ± 3.96 SD to 43.18 ± 2.23 SD, also K2 is significantly improved from 46.40 ± 4.99 SD to 44.35 ± 1.76 SD. Anterior corneal astigmatism showed marked improvement from -7.30 ± 7.45 SD to –1.16 ± 2.09 SD. K max also showed significant improvement from mean 49.16 ± 6.02 SD to 46.26 ± 2.17 SD. The average elevations in central 3 mm in anterior elevation map changed significantly from mean 4.14 ± 3.55 SD to 3.34 ± 1.75SD.The average elevations in central 3 mm in posterior elevation map changed significantly from mean 10.68 ± 15.97 SD to 5.50 ± 5.24 SD. Regarding the recurrence, only one case with autograft had recurrence compared to no recurrences with using MMC. Regarding the post operative hyperemia and inflammation, we noticed that MMC had alower rates of these complications post operatively. Conclusion: Successful pterygium surgery significantly improves the refraction and manages the flattening effect of pterygium on corneal topography. MMC decreases the rate of recurrence and post operative inflamations. Keywords: Mitomycin c. INTRODUCTION Pterygium is a degenerative disorder of the conjunctiva. It is usually seen as a triangular fleshy fibrovascular proliferation from the bulbar conjunctiva onto the cornea, located mostly on the nasal side. (McCarty CA, et al, 2000) In advanced cases it can affect vision as it invades the cornea causing astigmatism and scarring. Many people complain of cosmetic appearance. The most important complication after surgery is the recurrence rate. (Kosol K, 2003) Horizontal flattening is the most frequent corneal topographic change in eyes with pterygia. Several mechanisms have been reported to explain corneal flattening induced by pterygium. Pooling of tears at the pterygium apex plays an important role in corneal topographic changes. In fact, a tear meniscus developing between the corneal apex and elevated pterygium may flatten the normal corneal curvature in that area. Preoperative topography revealed the expected with the rule astigmatism in most of the younger patients and more bizarre patterns in the older patients. (Yilmaz S, et al 2008)