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 (Kmax) value of more than 58 diopters (D). METHODS: This prospective interventional case series involved patients with advanced progressive keratoconus with a Kmax of more than 58 D. The best-corrected visual acuity (BCVA), uncorrected visual acuity (UCVA), Kmax, mean keratometry (Kmean) 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 μm to 431.43 ± 61.92 μm (P = 0.005) after 24 months. The decreases in the mean logMAR of the BCVA, Kmax and Kmean 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 Kmax value of more than 2.0 D, which was indicative of treatment failure. In contrast, most other eyes showed a decrease in the Kmax 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.