Reducing higher-order aberrations after keratorefractive lenticule extraction using asymmetric spacing spot/track distances with low-energy levels

Abstract

Purpose: To compare the visual outcomes and changes in corneal higher-order aberrations (HOAs) after keratorefractive lenticule extraction (KLEx) using conventional symmetric spot/track distance laser spacing vs modified asymmetric spot/track distance laser spacing. Setting: Yonsei University College of Medicine and Eyereum Eye Clinic, Seoul, South Korea. Design: Retrospective comparative case series. Methods: This study included patients who underwent KLEx for myopia treatment. These patients were treated with either conventional symmetric spot/track distance laser spacing or modified asymmetric spot/track distance laser spacing, with both protocols maintaining constant treatment dose and pulse energy. Visual acuity and corneal HOAs were measured preoperatively and 1 month postoperatively. Results: 530 eyes of 265 patients were analyzed. The postoperative uncorrected distance visual acuity and corrected distance visual acuity showed no significant differences between the symmetric and asymmetric spacing groups. The postoperative total HOAs in the symmetric and asymmetric spacing groups were 0.62 +/- 0.20 and 0.50 +/- 0.15, respectively ( P < .001). The postoperative total coma in the symmetric and asymmetric spacing groups was 0.38 +/- 0.20 and 0.29 +/- 0.14, respectively ( P < .001). The postoperative spherical aberration (SA) in the symmetric and asymmetric spacing groups was 0.36 +/- 0.14 and 0.24 +/- 0.14, respectively ( P < .001). Analysis of the induced HOAs in both groups revealed that the asymmetric spacing group experienced lower induced total HOAs, vertical coma, and SAs ( P < .001). Conclusions: KLEx using modified asymmetric laser spacing yielded postoperative visual outcomes comparable with those achieved with conventional symmetric laser spacing while inducing significantly fewer corneal HOAs in the early postoperative period.