The Outcome of Corneal Collagen Cross-Linking in Patients with Advanced Progressive Keratoconus: A 2-Year Follow-up Study

PURPOSE: The aim of this study was to evaluate the safety and efficacy of collagen cross-linking (CXL) in advanced progressive keratoconus with a maximum keratometry (K-max) value of more than 58 diopters (D). METHODS: This prospective interventional case series involved patients with advanced progressive keratoconus with a K(ma)x of more than 58 D. The best-corrected visual acuity (BCVA), uncorrected visual acuity (UCVA), K-max, mean keratometry (K-mean) value, corneal astigmatism, and thinnest corneal thickness before surgery and 24 months after CXL were determined for 30 eyes of 27 patients. A Pentacam was used to measure the paraclinical parameters. RESULTS: The mean age of the patients was 24.47 +/- 3.33 years. The mean logarithm of the minimum angle of resolution (logMAR) of the uncorrected visual acuity UCVA decreased from 0.73 +/- 0.36 D at baseline to 0.48 +/- 0.30 D (P = 0.01), while the mean thinnest point thickness of the cornea decreased from 438.65 +/- 40.11 mm to 431.43 +/- 61.92 mm (P=0.005) after 24 months. The decreases in the mean logMAR of the BCVA, K-max and K-mean values, and corneal astigmatism were not statistically significant (P=0.05) at the 24-month follow-up. Progression was halted in 29 eyes (96.6%); only 1 eye (3.3%) showed an increase in the K-max value of more than 2.0 D, which was indicative of treatment failure. In contrast, most other eyes showed a decrease in the K-max value although it was not statistically significant. There were no major complications in any of the patients during the study period. CONCLUSION: Standard CXL treatment was safe and stabilized both the visual acuity and tomographic parameters at the 2-year follow-up in eyes with advanced progressive keratoconus.