Higher-order aberration 4 years after corneal collagen cross-linking

Abstract

Purpose: Corneal collagen cross-linking (CXL) is a treatment strategy used in keratoconic eyes. Evaluation of long-term changes of higher-order aberrations (HOAs) after CXL is useful in understanding the efficacy of this procedure in improving optical, refractive, and visual acuity. This study aims to investigate the long-term effect of CXL on ocular HOA in patients with progressive keratoconus (KC). Methods: Using an OPD-Scan II aberrometer, ocular HOAs measurements of 56 eyes of 56 patients that underwent CXL was evaluated at the baseline, 1, 2, and 4 years after the procedure. All OPD-Scan measurements were decomposed into Zernike coefficients from 3^rd to 6^th order. Results: The results revealed that except for a few parameters, most of the aberration parameters continuously decreased during the study. In the 4-year postoperative period, a statistically significant improvement in all HOA parameters except 5^th order Zernike polynomials (Z₅¹, Z₅⁻¹, Z₅³, Z₅⁻³, Z₅⁵, and Z₅⁻⁵) was observed. All the values significantly decreased compared to the preoperative measurements (P < 0.05). The mean ± standard deviation (SD) root mean square of the 3^rd, 4^th, and the 5^th order as well as coma, coma like, and total HOA parameters were significantly decreased compared to both preoperative and previous visits (P < 0.001). There were significant correlations between preoperative measurements of HOAs parameters with best-corrected visual acuity (BCVA) including Z₃¹, Z₃⁻¹, Z₄⁰, Z₅¹, and Z₄². Moreover, all the HOAs parameters in 4 years after the CXL were significantly correlated with BCVA (P < 0.05). Conclusion: CXL is effective in improving HOA parameters in eyes with progressive KC during a long-term follow-up.