Effects of topical vitamin E on keratocyte apoptosis after traditional photorefractive keratectomy

Purpose: To evaluate the keratocyte apoptosis and effects of topical vitami n E on keratocyte apoptosis after photorefractive surgery. Methods: Rabbits were divided into 7 groups, and all groups were compared with controls aft er epithelial scraping, epithelial scrape and photorefractive keratectomy ( PRK) (traditional PRK), transepithelial PRK, production of a corneal flap w ith microkeratome and laser-assisted in situ keratomileusis (LASIK). The ef fects of topical Vitamin E treatment were investigated in the traditional P RK group. The terminal deoxyribonucleotidyl transferase-mediated dUTP-digox igenin nick-end labelling assay (to detect DNA fragmentation in situ) and l ight microscopy have been used to detect apoptosis in rabbit cornea, Result s: Transepithelial PRK induced minimal keratocyte apoptosis, less than in a ll other refractive surgical procedures. The greatest amount of keratocyte apoptosis was observed after traditional PRK (p = 0.001), therefore we test ed the effects of topical vitamin E in this group. The number of apoptotic keratocytes significantly reduced after vitamin E therapy (p < 0.005). Conc lusion: Keratocytes undergo apoptosis after refractive surgery in response to mechanical epithelial removal, preparing of corneal flap and excimer las er stromal photoablation. The topical application of vitamin E immediately after surgery can prevent keratocyte apoptosis, and this result suggests th at free radicals may be partly responsible for keratocyte apoptosis after e xcimer laser keratectomy. Copyright (C) 2001 S.Karger AG, Basel.