Predictability of excimer laser treatment of myopia and astigmatism by the VISX Twenty-Twenty

Abstract

BackgroundTo determine the predictability of excimer laser photorefractive keratectomy (PRK) to correct myopia, astigmatism, or both between -1.00 and -19.00 diopters (D).SettingRoyal Victorian Eye and Ear Hospital, East Melbourne, Australia.MethodsThis study comprised 1218 consecutive eyes treated with a VISX Twenty-Twenty excimer laser and followed prospectively for 12 months. Low myopia was treated with one ablation zone (6.0 mm), high myopia with two ablation zones (5.0 and 6.0 mm), and extreme myopia with three ablation zones (4.5, 5.0, and 6.0 mm). Maximum spherical treatment was 15.00 D at the corneal plane. Data were analyzed to determine the predictability of the postoperative outco..