Comparative analysis of the corneal biomechanical characteristics between transepithelial and epithelium-off corneal cross-linking in keratoconus

Purpose This study aimed to compare corneal biomechanical changes after epithelium-off (OFF) versus transepithelial (ON) corneal collagen cross-linking (CXL) in patients with keratoconus. Methods A total of 148 eyes from 103 patients were included, with 86 eyes undergoing OFF-CXL and 62 eyes undergoing ON-CXL. Comprehensive preoperative assessments using Corvis ST imaging were performed and repeated at 1 and 6 months postoperatively. Changes in 30 dynamic corneal response (DCR) parameters from baseline to each follow-up time point were calculated and compared between groups. Statistical analyses were performed using independent samples t-tests for normally distributed data and non-parametric tests for non-normal data, with statistical significance defined as P ≤ 0.05. Results The OFF-CXL group exhibited significantly greater reductions in A1 velocity, A2 velocity, and HC deflection amplitude, as well as greater increases in ARTh at both 1 and 6 months (P < 0.05). Additionally, five other DCR parameters—Deflection Amplitude Max, Peak Distance, A2 Deformation Amplitude, and Integrated Radius—showed significant intergroup differences at 6 months, all demonstrating greater changes in the OFF-CXL group. Conclusion These results indicate that epithelium-off CXL induces more pronounced biomechanical strengthening compared to transepithelial CXL, potentially leading to a reduced risk of disease progression. Although transepithelial CXL offers advantages in safety and patient tolerance, protocol refinements may be necessary to achieve biomechanical efficacy comparable to that of epithelium-off CXL.