Effect of Ablation-Zone Diameter on Whole-Corneal Higher-Order Aberrations After LASEK: A Retrospective Study

Purpose: To evaluate whether modest differences in programmed ablation-zone diameter (AZD) during LASEK affect postoperative whole-corneal higher-order aberrations (HOAs), with emphasis on spherical aberration (SA) and coma (CA). Methods: This retrospective single-center observational study included 120 right eyes that underwent LASEK between January 2020 and June 2025. 120 eyes were grouped by programmed AZD: 5.75 mm (n=41), 6.00 mm (n=40), and 6.25 mm (n=39). Corneal HOAs (total HOA RMS, SA, CA, trefoil aberration) were measured by Pentacam at baseline, 1 and 3 months. Analyses included absolute changes, HOA normalized per treated diopter, and matched-pair sensitivity comparisons. Statistical tests included t tests, ANOVA and χ²; significance set at P<0.05. Results: All groups showed significant postoperative increases in total HOA, SA and CA at 3 months (P<0.001). In unadjusted analyses, larger programmed AZDs exhibited smaller absolute increases in total HOA, SA and trefoil (P<0.001). After normalization by diopter these zone-dependent differences were largely attenuated (P>0.05 for most comparisons). Matched-pair analyses confirmed AZD enlargement consistently reduced SA but tended to increase CA (matched comparisons P<0.05), yielding no uniform net reduction in total HOA. Conclusions: Larger programmed AZDs in LASEK are associated with smaller absolute induction of SA, CA and total HOAs at 3 months, but this apparent benefit is largely mediated by baseline refractive magnitude and is disappeard after diopter normalization. Matched-pair analyses showed AZD enlargement reduced SA but increased CA without net HOA benefit; therefore precise centration is essential.