Establishing Analysis Parameters for Spherical Aberration after Wavefront LASIK

To compare preoperative and postoperative spherical aberration, coma, and other higher order aberrations from wavefront LASIK at varying pupil analysis diameters and different myopic corrections, and to determine acceptable parameters for wavefront measurements. Nonrandomized retrospective chart review. Twenty-one eyes of 12 patients who had CustomCornea LASIK with the LADARVision 4000 (Alcon, Fort Worth, TX). Wavefront analyses were performed before and 3 months after CustomCornea LASIK using a 6.5-mm central optical zone and blend zone to 9.0 mm. Wavefront measurements were made with pupil analysis diameters of 5.5, 6.0, 6.5, and 7.0 mm. Myopic corrections were divided into 3 spherical equivalent subgroups: low (6 D). Main outcome measures were compared based on myopic subgroup within each analysis diameter. Results were analyzed with analysis of variance and paired t tests. Spherical aberration, coma, and other higher order aberrations. There were no significant increases in coma or other higher order aberrations postoperatively or with larger analysis diameters. There was a significant increase in postoperative differences in spherical aberration between 6.5 and 7.0 mm for the >6-D myopic correction subgroup ( P = 0.03). Differences between other 0.5-mm intervals and other subgroups were not significant. The largest difference between preoperative and postoperative spherical aberration occurred at the analysis diameter 0.5 mm greater than the laser optical zone for the subgroup with high myopic correction. To detect larger degrees of induced spherical aberrations, analysis diameters 0.5 mm larger than the central laser optical zone should be considered.