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

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.

Prospective randomized clinical trial.

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.

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.

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.