Abstract
PURPOSE: To assess the retinal peripheral defocus changes following femtosecond laser in situ-keratomileusis (FS-LASIK) in myopic adults and analyse influencing factors. METHODS: This study recruited 202 patients who underwent FS-LASIK with myopia at Beijing Ming Vision Eye Hospital. Participants were divided into low myopia (LM, -0.50D to -3.00D), moderate myopia (MM, -3.00D to -6.00D), and high myopia (HM, ≥-6.00D) groups according to spherical equivalent (SE). We measured axial length (AL), total retinal defocus (TRDV), and defocus values at eccentricities ranging from 0° to 53° from the fovea, and defocus values at the superior, inferior, temporal, and nasal quadrants. With a 3-month follow-up, changes in peripheral defocus (ΔRDV) were recorded and analysed. RESULTS: No significant differences were observed in TRDV, RDV20°-53°, and RDV-S among the three groups after surgery (all P > 0.05). RDV at 10°-53° increased with eccentricity, while all groups showed significant reductions in hyperopic defocus at 20°-53° compared to preoperative measurements (all P < 0.05). This reduction was more pronounced with severe myopia and greater eccentricity. Correlation analysis revealed that ΔRDV20°-30° and ΔRDV30°-40° positively correlated with SE and negatively correlated with AL and cutting thickness. ΔRDV40°-53° negatively correlated with AL. ΔRDV-T negatively correlated with SE, ΔRDV-N positively correlated with SE and negatively correlated with AL and cutting thickness (all P < 0.05). CONCLUSION: FS-LASIK does not change the asymmetric distribution of RDV after surgery. It effectively reduces hyperopic defocus within the 20°-53° range around the fovea, with greater reductions noted peripherally. Higher myopia and greater cutting thickness are associated with larger defocus reductions.