Impact of eye movement on postoperative optical aberrations and refractive outcomes in LASIK surgery

PURPOSE: To examine the influence of eye movement variability on postoperative higher-order aberrations (HOAs), and refractive and astigmatic changes after femto laser in situ keratomileusis (LASIK). SETTING: American University of Beirut Medical Center. DESIGN: Retrospective study. METHODS: A retrospective analysis was conducted on 94 eyes from 47 patients treated with the SCHWIND AMARIS system. Intraoperative eye-tracking data captured horizontal (X) and vertical (Y), and radial (R) positional shifts, with variability quantified using mean and SD. Correlation analyses examined the impact of movement fluctuations on postoperative corneal HOAs at 3 months, both unscaled and scaled by planned spherical equivalent (SEq) and astigmatism. Analyses were conducted on the full dataset and repeated using 1 eye per patient (right eyes only) after exclusion of high-influence points to eliminate pseudoreplication and assess robustness. RESULTS: Increased intraoperative fixation variability was associated with greater postoperative aberrations, with the strongest and most consistent correlations observed for spherical aberration (SA). Variability in horizontal, vertical, and radial eye positions showed significant associations with induced SA, which were strengthened when positional measures were scaled by planned SEq. Several associations, particularly those involving SA, remained significant after removing high-influence points and were partially preserved in the 1-eye sensitivity analysis. CONCLUSIONS: Fixation instability (leading to movement variability) is consistently associated with increased induction of SA, and to a lesser extent, other HOAs after FemtoLASIK. Improvements in eye-tracking technology performance and fixation stability may reduce aberration induction and improve refractive outcomes.