Comparison of Standard versus Accelerated corneal collagen cross-linking for keratoconus: one-year outcomes from Save Sight Keratoconus Registry study

Abstract

Purpose : The literature on effectiveness of Standard (UV power: 3mW/cm², UV duration: 30 min) vs Accelerated (UV power: 9mW/cm², UV duration: 10 min) corneal cross-linking (CXL) for stabilizing progressive keratoconus is divided. The aim of this study was to compare the efficacy and safety of these protocols in keratoconus using real-world data from the Save Sight Keratoconus Registry (SSKR).

Methods : This observational study included 233 eyes (197 patients) who had Standard CXL and 375 eyes (292 patients) who had Accelerated CXL, with a follow-up visit at one-year post CXL. The changes in presenting visual acuity, maximum keratometry (Kmax), and central keratometry (K2) were the primary outcome measures. Secondary outcome measures included the changes in pinhole visual acuity, thinnest corneal pachymetry, and incidence of adverse events. Independent t-tests or chi-squared tests were performed when appropriate.

Results : Age, gender, visual acuity, Kmax and thinnest pachymetry at baseline were similar between the Standard and Accelerated CXL groups. One-year post CXL, both groups had increase in presenting visual acuity (mean gain in logMAR letters: 5.0 [95% CI, 2.9 to 7.2] vs 4.8 [95% CI, 3.3 to 6.4], respectively) and pinhole visual acuity (mean gain in logMAR letters: 2.9 [95% CI, 1.4 to 4.4] vs 2.0 [95% CI, 1.0 to 3.1], respectively). Similarly, both Standard and Accelerated CXL groups had a decrease in Kmax (mean change: -0.8 [95% CI, -1.3 to -0.3] D vs -1.6 [95% CI, -2.2 to -1.0] D, respectively), K2 (mean change: -0.5 [95% CI, -1.0 to -0.1] D vs -0.8 [95% CI, -1.1 to -0.5] D, respectively) and thinnest pachymetry (mean change: -12.5 [95% CI, -16.4 to -8.6] µm vs -17.2 [95% CI, -20.2 to -14.2] µm, respectively). However, there was no statistically significant difference between the CXL groups for any of these outcome measures (p > 0.05 in all cases). The incidence of adverse events, particularly haze, was higher in the Accelerated CXL group (all adverse events: 69 eyes, 18.4%; haze: 62 eyes,16.5%) than the Standard CXL group (all adverse events: 24 eyes, 10.3%; haze: 19 eyes, 8.2%; p-value <0.05 in both cases).

Conclusions : This study found that both Standard and Accelerated CXL were similarly effective in stabilizing progressive keratoconus. However, the incidence of adverse events was higher in the Accelerated CXL group.

This is a 2020 ARVO Annual Meeting abstract.