Two-Year Changes in Corneal Spherical Aberration After Laser-Assisted In Situ Keratomileusis and Photorefractive Keratectomy in Regular and Wavefront-Guided Ablations

The aim of this study was to analyze the changes in corneal spherical aberration following regular ablation (RA) and wavefront-guided (WFG) ablations in photorefractive keratectomy (PRK) and laser-assisted in situ keratomileusis (LASIK). A retrospective analysis was performed on the eyes that underwent femtosecond LASIK or PRK between January 2016 and December 2018. Changes in the corneal spherical aberration were measured preoperatively and postoperatively with a high-resolution Scheimpflug camera system, and they were correlated with the attempted correction and all other tomography parameters. Of the 3826 eyes that were reviewed, 484 eyes met the inclusion criteria and were enrolled in the study. Seventy-four eyes underwent PRK and 410 eyes underwent LASIK. The LASIK and PRK subgroups were similar in terms of the general demographics, preoperative higher-order aberrations, and manifest spherical equivalent. The changes in spherical aberration were significantly correlated with the attempted correction in both LASIK (y =  –0.35x and R2 = 0.42 for myopic WFG; y =  –0.18x and R2 = 0.19 for myopic RA; y =  –0.44x and R2 = 0.49 for hyperopic WFG; y =  –0.53x and R2 = 0.69 for hyperopic RA) and PRK (y = –0.20x and R2 = 0.25 for myopic WFG; y = –0.37x and R2 = 0.44 for myopic RA). No other preoperative parameters except corneal asphericity, axial length, and anterior chamber depth were significantly correlated with the changes in the spherical aberration. LASIK correction had a higher induction of spherical aberration compared with that of PRK, and the beneficial effect of the WFG treatment on spherical aberration was mainly visible in the PRK-treated eyes.