Role of Cistein in Corneal Reepithelization After Photorefractive Keratectomy

Abstract

Purpose: : to evaluate the effect of cystein oral supplements in the process of corneal reepithelization after photorefractive keratectomy (PRK).

Methods: : 100 patients ( 200 eyes) , divided into two groups ( Group 1 and Group2 ) with the same age and comparable refractive errors, each made of 100 patients , have been monitored. It was administered to patients in Group 1 oral L–cystein, with a daily dose of 200 mg for 15 days starting from 1 week before srgery, using the other group( Group 2) as a control. After surgery , patients have been daily monitored starting from 24 hours following surgery,through biomicroscopy , to measure the epithelial diameter defect; patients were then monitored on 1th , 2th, 3th, 4^th week after surgery trhough confocal microscopy, to value epithelial corneal thickness.

Results: : eyes in Group 1 showed a time of reepithelization inferior to patients in Group 2 ( 102 ± 15 verus 159± 9 hours); The following values of corneal epithelium thickness come from the measurements by confocal microscopy, during the pre–operative visit and on the 1^st , 2^nd , 3^rd and 4^th week after surgery. Mean value of corneal epithelium thickness before surgery was 51±5 µm (51±4 µm in Group 1 and 52±4 µm in Group 2). At week 1 the value of the thickness of the newly–formed epithelium was: 29+–4 µm in the patients of Group 1 and 22±3 µm in the control patients of. At week 2: 37±5 µm in Group 1 and 29±2 µm in Group 2. At week 3: 45±4 _m in Group 1 and 35±4 _m in Group 2. At week 4: 50± _m in Group 1 and 43±3 µm in Group 2. During the follow–up confocal microscopy showed a superior newly–formed corneal epithelium thickness in group 1. At week 4 mean value of corneal epithelium thickness observed in Group 1 was 7±2 µm greater than Group 2, (similar to mean value of the same patients during the pre–operative examination).

Conclusions: : Cisteyn, administered orally in a daily dose of 200 mgs, is shown to be effective in reducing time of corneal reepithelization after PRK and also aids the return of the epithelial thickness to the original levels without apparent inducing meaningful changes at a systemic level or ocular level.

Keywords: cornea: epithelium • refractive surgery: PRK • drug toxicity/drug effects