Comparison on 3 methods of transepithelial corneal collagen cross-linking for the treatment of keratoconus

Abstract

Objective To compare the efficacy of 3 different methods of transepithelial corneal collagen cross-linking (CXL) techniques for the treatment of keratoconus. Methods Retrospective cases analysis. Thirty eyes of 24 cases with keratoconus were divided randomly into 3 groups. Each group contained 10 eyes. Group A received hypotonic CXL, group B received iontophoresis CXL (I-CXL) for 5 min, and group C received I-CXL for 10 min. All cases received visual acuity, Phoroptor, Pentacam, confocal laser corneal microscopy examination before and 1, 3, 6 and 12 months after surgery. Optical coherence tomography was taken 1 week after surgery. Results The uncorrected visual acuity (UCVA, log MAR) 12 months after surgery was improved in group C (t=2.646, P=0.023), and UCVA in group B wasn’t significantly increased (t=1.458, P=0.170). The best corrected visual acuity (BCVA) in 3 groups were improved in some degree after surgery. Maximal keratometry (Kmax) slightly decreased in group C, and Kmax in group A and group B were stable. The phenomenon of stroma cell apotosis-activate-regeneration appeared most significant in group C. The corneal thickness of thinnest point and the density of endothelial cell among 3 groups were not changed between preoperatively and 12 months postoperatively. Demarcation line by OCT showed (143.8±37.9) μm in group A, (213.6±42.3) μm in group B and (237.0±46.4) μm in group C. The differences were statistically significant among the 3 groups (F=7.703, P=0.003). Conclusion Three methods of the CXL can control the progression of keratoconus, among which the most effective program is 10 minutes I-CXL. Key words: Keratoconus; Corneal collagen cross-linking, transepithelial, iontophoresis, hypotonic