Corneal Aberration Changes After Hyperopic LASIK: A Comparison Between the VISX Star S2 and the Asclepion-Meditec MEL 70 G Scan Excimer Lasers.

PURPOSE: To compute and compare anterior corneal aberration changes following hyperopic LASIK using two different excimer lasers: the VISX Star S2 and the Asclepion-Meditec MEL 70 G Scan. METHODS: The right eyes of 43 patients with preoperative refraction ranging from +0.75 to +5.50 diopters (D) and astigmatism ranging from 0.00 to 1.00 D were randomly divided into two groups. The first group was operated with the Star S2, a broad-beam excimer laser (n=22), and the second group with the MEL 70, a flying-spot excimer laser (n=21). Total higher order aberrations (Z_nⁱ, n≥3), coma (Z^±1/3, Z^±1/5), and spherical aberration (Z₄⁰) values were computed from videokeratography using CTView software preoperatively and 6 months postoperatively, for 3.0- and 6.5-mm aperture diameters. RESULTS: Higher order aberrations, coma, and spherical aberration increased after hyperopic LASIK and were greater for larger pupil diameters in both groups. No statistically significant differences were found between the Star S2 and MEL 70 excimer lasers in terms of aberrometric increase, mean postoperative visual acuity, and residual refraction. CONCLUSIONS: Anterior corneal aberrations increase after hyperopic LASIK. The type of laser (Star S2 versus MEL 70) seems to have no impact on the amount of anterior corneal aberrations induced after hyperopic LASIK. [ABSTRACT FROM AUTHOR]