Myopia Research Today is a free monthly online journal that collates and summarizes the latest research about Myopia, including details on treatment, prevention, causes, correction.

A prospective randomized clinical trial of laser in situ keratomileusis with two different lasers.

Twa MD, Lembach RG, Bullimore MA, Roberts C

College of Optometry, The Ohio State University, Columbus 43210, USA.

PURPOSE: To compare optical quality, visual function, corneal shape, ocular wavefront aberrations, and patient-reported symptoms and satisfaction after laser in situ keratomileusis (LASIK) with two different excimer lasers. DESIGN: Prospective randomized clinical trial. METHODS: In an institutional practice setting, 60 eyes of 30 patients with low to moderate myopia were randomized to receive LASIK in one eye with the Technolas 217A; the other eye was treated with the VISX S3. Patients were followed for 6 months after surgery. The primary outcome measure was best spectacle-corrected visual acuity. RESULTS: At 6 months, the mean best-spectacle corrected high contrast visual acuity was similar between the two treatment groups: mean difference (95% confidence interval) was -0.01 logarithm of minimal angle of resolution (logMAR) (-0.03 to +0.01 logMAR). Uncorrected visual acuity differences were also not significant. The difference in residual spherical equivalent subjective refractive error between treatment groups was -0.15 diopter (-0.34 to +0.05 diopter). Spherical aberration increased in both groups after treatment, and the change in root mean square (RMS) ocular wavefront error was greater in the VISX group by +0.07 microm (+0.03 to +0.11 microm). After LASIK, corneal curvature was steeper in the midperipheral region among VISX-treated eyes by +1.39 diopters (+2.06 to +0.72 diopters). There were no patient-reported differences in satisfaction between eyes. CONCLUSIONS: There were no significant differences in visual acuity or refractive outcomes attributed to either laser under any of the conditions measured. There was also no significant difference in patient-reported symptoms, satisfaction with treatment, or eye preference associated with either laser. Additional study is needed to establish the importance of differences in higher-order optical aberrations and corneal shape that we observed in these two treatment groups.

Published 9 August 2005 in Am J Ophthalmol, 140(2): 173-83.
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