Excimer laser photorefractive keratectomy for myopia.

Abstract

To evaluate the safety, effectiveness and stability of excimer laser photorefractive keratectomy (PRK) treatment, we studied its posttreatment results in 44 normal-sighted myopic eyes where a 193-nm emission wavelength excimer laser was used to correct myopia. The eyes were divided into three groups according to the preoperative refractive error and attempted correction: group I, preoperative myopia < or = 6.00 diopters (D), full correction; group II, preoperative myopia between 6.00 and 8.00 D, full correction; group III, preoperative myopia > 8.00 D, attempted correction of 8.00 D. Percentages of relative spherical equivalents (ie, observed spherical equivalent -- expected spherical equivalent) within +/- 1.0 D 3 months after treatment were 95% in group I, 64% in group II and 67% in group III. Uncorrected visual acuity of 20/40, or better, was achieved in 100% of eyes in group I, and 92% in group II at 6 months. Initial overcorrection followed by myopic regression was observed in all groups. The refractive outcome in our study was stable 3 months after surgery. Anterior stromal haze was mild and disappeared gradually 3 months postoperatively. The greater the diopter correction needed, the higher the grade of corneal haze (p < 0.01). There were no significant complications. The results of this study demonstrated that excimer laser PRK appears to be a reasonably predictable and stable procedure to correct low to moderate myopia.