Quality of vision improves with wavefront-guided system

February 15, 2005

Barcelona, Spain—The Zyoptix system (Bausch & Lomb) for wavefront-guided ablation is as effective as the conventional Planoscan (Bausch & Lomb) LASIK procedure in the correction of low to moderate myopia. Zyoptix, however, is advantageous because it induces less total, higher-order, and third-order aberrations. In addition, the quality of vision under low illumination and with low-contrast objects is better than that achieved with Planoscan, according to Jorge Castanera, MD, and Carlos Rios, OC.

The investigators conducted a study at the Instituto de OftalmologíCastanera, Barcelona, Spain, in which they evaluated the efficacy and safety of the two systems. The 25 study patients were treated in one eye with the Zyoptix system with Zylink 2.33 software and in the other eye with Planoscan.

"We used very strict inclusion criteria so that both eyes were equal. We then selected randomly one eye for Zyoptix treatment and the contralateral eye served as control and was treated with Planoscan," explained Dr. Castanera, medical director, Instituto de Oftalmología Castanera.

In the eyes treated with Planoscan, the mean spherical equivalent was -4.14 ± 1.91 D (range, -1.13 to -9 D), the sphere was -3.90 ± 1.82 D (range, -1 to -8.5 D), and the cylinder was -0.48 ± 0.44 D (range, 0 to -1.5 D).

In the eyes treated with Zyoptix, the mean spherical equivalent was -4.15 ± 1.77 D (range, -1.5 to -9 D), the sphere was -3.85 ± 1.66 D (range, -1.5 to -8.5 D), and the cylinder was -0.59 ± 0.44 D (range, 0 to -1.75 D). Dr. Castanera reported that the results were analyzed for up to 3 months after the treatment and that there was no difference in the refractive results or in the uncorrected visual acuity between the two groups.

The spherical equivalent was very stable and similar in the two groups at 1 week, 1 month, and 3 months after the surgery, 0.13, -0.01, and -0.09 D, respectively, in the eyes treated with Zyoptix and -0.24, -0.08, and -0.18 D in the eyes treated with Planoscan. The uncorrected visual acuity levels in LogMAR units at 1 week, 1 month, and 3 months in the eyes treated with Zyoptix were -0.08, -0.1, and -0.09, respectively. In the eyes treated with Planoscan the respective values were 0.24, -0.08, and -0.18.

Dr. Castanera also reported that the eyes treated with Zyoptix had significantly less total and higher-order aberrations and less third-order aberrations. Both comparisons reached statistical significance at the 3-month time point (p = 0.002 for total higher-order aberrations and p = 0.0003 for third-order aberrations).