Comparison of ablation centration in initial and retreatment active eye-tracker-assisted laser in situ keratomileusis and the effect on visual outcome

Abstract

Purpose: To evaluate the relationship between initial and retreatment ablation centers in active eye-tracker-assisted myopic laser in situ keratomileusis (LASIK) and determine whether the relationship between the 2 ablation centers influences the visual outcome after retreatment. Setting: Department of Ophthalmology, China Medical University Hospital, Taichung, Taiwan. Methods: This retrospective study comprised 21 eyes of 15 patients who had retreatment at least 3 months after primary myopic LASIK by lifting the initial flap. Corneal topography and best corrected visual acuity (BCVA) were evaluated preoperatively and 3 months postoperatively. The ablation centration was analyzed by corneal topography preoperatively and at 3 months. Results: The mean decentration of the primary treatment was 0.43 mm ± 0.21 (SD) and of the retreatment, 0.34 ± 0.15 mm. There was no significant difference between them ( P = .07). The 2 ablation centers were close each other. The mean distance between the 2 ablation centers was 0.29 ± 0.18 mm and the mean angle between them, 39.7 ± 46.2 degrees. The BCVA was unchanged after retreatment regardless of the relationship between the 2 ablation centers. Conclusions: With an active eye-tracking system, the retreatment center was not only close to the pupil center but also close to the primary ablation center. Regardless of the relationship between the 2 ablation centers, the BCVA did not change if the retreatment ablation was well centered.