Corneal Higher-order Aberrations Changes after Accelerated Cross-linking for Keratoconus

Aim: To evaluate changes in corneal higher-order aberrations (HOAs) after accelerated corneal cross-linking (A-CXL) and the effect of change in HOAs on visual acuity between baseline and one year after A-CXL. Methods: : In this retrospective case-series, 32 eyes of 24 patients with keratoconus (KC) underwent accelerated corneal cross-linking. The following anterior corneal HOAs: total corneal HOAs, trefoil, secondary trefoil, coma, secondary coma, secondary astigmatism and spherical aberrations were measured and analysed using the Scheimpfug-Placido Sirius (CSO, Italy) topographer at baseline and 12 months after CXL. Multivariate analysis was used to evaluate the independent effect of HOA subtypes on changes in uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA). Results: : At one year post CXL, UDVA and CDVA were significantly improved, -0.13 ± 0.19 LogMar (P = 0.0005) and -0.08 ±.0.11 LogMar (P = 0.0003), respectively. The mean preoperative trefoil, secondary trefoil, secondary coma and secondary astigmatism were 0.95 ± 0.46; µm, 0.20 ± 0.11; µm, 0.29 ± 0.19; µm and 0.42 ± 0.17 µm, respectively. At one year, the mean values decreased significantly to 0.77 ± 0.47 µm, 0.15 ± 0.11 µm, 0.25 ± 0.18 µm and 0.34 ± 0.18 µm, respectively (P < 0.05, for all). While no independent relationship between any HOA changes and change in UDVA was observed, there was a significant effect of the change in secondary coma on the change in CDVA (95% CI 0.01-1.34, P = 0.048; β = 0.67). Conclusion: Accelerated corneal cross-linking was shown to be effective in improving corneal HOAs in eyes with progressive keratoconus at one year follow-up. A change in secondary coma had a significant and independent effect on CDVA.