Objectives: The present study compares the results obtained with single zone PRK versus multiple zones PRK for treating low myopia. Methods: Nineteen patients presenting spherical equivalent up to 6.00 diopters of myopia, were submitted to PRK using two different approaches. Ramdomly one eye received a 6.0 mm spherical ablation (SZ) while the fellow eye was treated with two optical zones, 6.0 mm and 6.5 mm (MZ). All the procedures aimed to correct total spherical equivalent. Follow-up was carried out for at least 6 months. Results: The multizone group (MZ) presented a preoperative mean spherical equivalent of -2.87 diopters, ranging from -1.25 to -4.62D. In the single zone group, the mean spherical equivalent was -2.78 diopters, ranging from -1.37 to -4.62D. No significant difference was observed between the two groups considering final spherical equivalent (p=0.391). In the first postoperative month, 84% of the patients in the MZ group and 95% in the SZ group presented uncorrected visual acuity equal to or better than 20/40. No difference was detected regarding time necessary to achieve best uncorrected vision. Conclusion: Results obtained using different ablation profiles were similar in regard to spherical equivalent, induced astigmatism and complications. A better final uncorrected visual acuity trend was observed in the SZ group but it was not considered clinically significant. We believe that any of the evaluated approaches are valued methods for treating low myopia.
Keratectomy; Photorefractive; Excimer laser; Myopia
