Corneal Endothelial Cell Changes after Photorefractive Keratectomy for Low to Moderate Myopia With and Without Mitomycin-C

Abstract
Background: Mitomycin-C was suggested for application during surface ablation procedures to reduce post-operative haze formation. It can effectively reduce haze formation and hence, improve the predictability of visual outcomes following refractive surgery. Despite these advantages, MMC can po-tentially damage all three main corneal cell types including epithelial (differentiated epithelium and limbal cells), stromal (keratocytes), and endothelial cells.
Aim of Study: To investigate the croneal endothelial cell changes after Photorefractive Keratectomy (PRK) with and without Mitomycin-C 0.02% for low to moderate myopia.
Patient and Methods: This prospective, randomized, comparative study included 60 eyes of 30 patients who were chosen from Ophthalmology Clinic at Tanta University Hos-pital and Shorouk Laser Vision Correction Centre for 6 month from December 2017 to May 2018 and scheduled for Photo-refractive Keratectomy (PRK) using193nm wavelength exci-mer laser system Allegretto EX500, (Wave Light Technologie., USA). These patients were randomly divided into two groups. Group (A) were scheduled for (PRK) with adjunctive mito-mycin-C 0.02% and patients of Group (B) were scheduled for (PRK) without mitomycin-C. Informed consents were obtained from all study participants.
Results: In Group A the mean Endothelial Cell Density (ECD) was 2891.61±272.41 and at three months after surgery was 28 13.04±276.55cells/mm2 (p=0.289), pre-operative mean of Coefficient of Variation (CV) was 34.87±4.37 and post-operatively was 34.70±4.06 (p=0.877), the pre-operative mean of Central Corneal Thickness (CCT) was 523.00±26.14 m  and 467.36±40.61 m  post-operatively (p=0.001), the mean of hexagonality pre-operatively was 64.26±8.64% and 59.96±  8.15% post-operatively (p=0.059) which was statistically insignificant. In Group B the mean Endothelial Cell Density was (ECD) 2874.50±314.48 and at three months after surgery was 2777.23±302.44cells/mm2 (p=0.227), pre-operative mean of Coefficient of Variation (CV) was 33.49±4.98 and post-operatively 33.55±4.10 (p=0.962), pre-operative mean of central corneal thickness was 538.03±26.03 and 484.50±20.55 post-operatively (p=0.001), the mean of hexagonality pre-operatively was 63.00±7.74 and 61.43±7.29% post-operatively (p=0.423).
Conclusions: There's no significant effect on endothelium in patients underwent to PRK in low to moderate myopia with or without mitomycin-C. We can't judge the same results for patients with high myopia because the ablation depth will be more and theoretically the diffusion of mitomycin-C to en-dothelium would affect its function or count.