Assessing Eye Movement Dynamics and Fixation Stability Between Eyes During Same-Session Bilateral LASIK

To investigate eye movement dynamics during excimer laser ablation, specifically femtosecond laser-assisted in situ keratomileusis (FS-LASIK), and compare movement patterns between the right eye (always operated on first) and the left eye (operated on second), analyzing direction, magnitude, and temporal changes.

A retrospective analysis was conducted on 92 eyes from 46 patients who underwent FS-LASIK with the SCHWIND AMARIS system (SCHWIND eye-tech-solutions). Eye-tracking data were collected to record horizontal and vertical directional movements; variability was assessed using standardized metrics. Temporal trends were analyzed using split-interval and correlation methods.

Eye movement patterns revealed greater variability in the vertical direction (t-test [t] = -2.32, P = .02) than in the horizontal direction (t = -0.27, P = 0.79) for both eyes. The second eye showed more variability, particularly in the vertical direction, with earlier and more dynamic increases (correlation [r] = 0.20, slope 0.50, both P < .0005). Horizontal movements were initially reduced but gradually increased after 22 seconds (t = 2.02 for right eye, t = 2.09 for left eye, P = .04 for both). Vertical movements increased significantly after 13 seconds in the right eye (t = -2.06, P = .04) and 5 seconds in the left eye (t = -2.40, P = .02).

Eye movements during FS-LASIK exhibit dynamic variability, especially in the vertical direction. The second eye showed earlier, more pronounced movements as surgery progressed. These findings suggest the need to consider eye movement dynamics in surgical planning and system design.