Effect of optical zone ablation diameter on LASIK-induced higher order optical aberrations.

PURPOSE: To compare the postoperative higher order aberrations among eyes that had received conventional laser in situ keratomileusis (LASIK) treatment at different optical zone diameters using the Alcon LADARVision 4000 platform (Alcon, Ft Worth, Tex).

METHODS: Monochromatic wavefront aberrations at 6.5-mm pupil size of 96 eyes of 96 Hong Kong Chinese patients with normal myopic astigmatism were objectively measured using the Alcon LADARWave aberrometer before and after (at least 6 months) conventional LASIK with the Autonomous LADARVision 4000 excimer laser. Patients were divided into three groups according to optical zone diameter--group 1 (n=32), optical zone diameter <6.5 mm; group 2 (n=32), optical zone diameter 6.5 mm; and group 3 (n=32), optical zone diameter >6.5 mm).

RESULTS: Mean optical zone diameters of groups 1, 2, and 3 were 6.2+/-0.1 mm, 6.5+/-0.0 mm, and 6.9+/-0.2 mm, respectively. Total higher order, coma, and spherical aberrations before LASIK were 0.67+/-0.27 microm, 0.27+/-0.17 microm, and 0.41+/-0.14 microm in group 1; 0.56+/-0.26 microm, 0.28+/-0.15 microm, and 0.32+/-0.11 microm in group 2; and 0.62+/-0.25 microm, 0.34+/-0.15 microm, and 0.37+/-0.09 microm in group 3. After surgery, the aberrations increased to 1.20+/-0.21 microm, 0.71+/-0.25 microm, and 0.70+/-0.19 microm in group 1; 0.97+/-0.18 microm, 0.47+/-0.22 microm, and 0.69+/-0.13 microm in group 2; and 0.91+/-0.20 microm, 0.41+/-0.22 microm, and 0.56+/-0.12 microm in group 3. Compared to group 1, groups 2 and 3 had significantly less coma aberrations after LASIK (P=.03); the total high order aberration in group 3 was also significantly lower than in group 1 (P=.04) after treatment.

CONCLUSIONS: In conventional LASIK treatment using the Alcon LADARVision 4000 platform, a larger surgical optical zone diameter significantly decreases higher order aberrations after LASIK.