Corneal Thickness and Topography Indices after Collagen Cross-linking for Keratoconus: 18 Months Follow-up and Literature Review

Abstract

ABSTRACT Objective: To evaluate the changes in corneal topography indices and corneal thickness after cross-linking treatment for keratoconus. Study Design: Retrospective Observational Study Patients and Methods: The data of patients who underwent corneal collagen cross-linking treatment for keratoconus were retrieved. Central corneal thickness (CCT), maximum and mean keratometry (Kmax, Kmean) values and topography indices: index of surface variance (ISV), index of vertical asymmetry (IVA), keratoconus index (KI), central keratoconus index (CKI), minimum radius of curvature (Rmin), index of height asymmetry (IHA), and index of height decentration (IHD) were obtained from Pentacam and Wavelight-Allegretto Wave Topolyzer outputs. Follow-up was 18 months. Results: The study comprised of 15 eyes of 10 patients with keratoconus. Central corneal thickness had decreased significantly 1 month after the procedure (p=0.003) but there were no statistically significant changes between the baseline values and last visits (p>0.05). Kmax and Kmean values were not statistically different from the preoperative values and at the last visits (p>0.05). Almost all of the corneal topography indices improved significantly after postoperative 6th month (p<0.05). Conclusion: There were improvements in topography indices during 18-month follow-up period, suggesting that the cornea becomes more optically regular and symmetrical after cross-linking.