COMPARATIVE STUDY BETWEEN EPITHELIUM ON AND EPITHELIUM OFF COLLAGEN CROSS LINKING WITH RIBOFLAVIN AND UVR IN TREATMENT OF EARLY KERATOCONUS

Abstract

Objective: To compare the safety and efficacy epithelium on versus epithelium off collagen crosslinking with riboflavin and UVR in treatment of early keratoconus. Patients and Methods: Thepresent study was a prospective, randomized study. 40 eyes from 25 patients with a mean age of 24years (range: 15–35 years) were included. There were 15 males and 10 females, and all of themunderwent corneal CXL using riboflavin and ultraviolet-A light at the Tipa Eye Hospital, Assuit.Results: Among the included samples, 20 eyes underwent epithelium-on corneal collagen CXL, and20 eyes underwent epithelium-off corneal CXL. The incidence of postoperative pain was lowered byabout 20% in the trans-epithelial group as compared with the epithelial-off group in the first postoperative week. In addition, the incidence of postoperative corneal haze was lowered by about 50% inthe transepithelial group as compared with the epithelial-off group in the first postoperative week. Itwas also noticed that the CXL was formed in the upper-third of the corneal stroma, 20-30 μmbeneath bowman membrane in the transepithelial CXL technique, while in the classic debridementtechnique; it was formed much deeper in the stoma. In group I, after 3 and 6 months, there was anon-statistically significant corneal thinning. In group II, none statistically significant corneal thinningwas detected after 3 months, but after 6 months there was some regression in the form of cornealthinning by nearly 5-10 μm in 20% of cases. Conclusion: Both epithelium-off CXL and the epitheliumon CXL were effective in stabilizing the progression of keratoconus at least for 6 months; however,the epithelium-off CXL appeared to be much more effective in improving the refractive best-correctedvisual acuity and topographic outcomes in keratoconic eyes compared with the epithelium-on CXL.