Long-term results of excimer photorefractive keratectomy for myopia and astigmatism using an aspherical algorithm

Abstract Purpose. To assess the efficacy of an aspherical algorithm in correcting myopia and myopic astigmatism. Methods. A Nidek EC 5000 laser was used. The calculation of the aspherical algorithm was based on the preoperative and intended corneal curvatures, the optical zone (OZ) size and the diameter of the aspherical peripheral ablation. The algorithm requires 25% less tissue ablation as compared to the multiple OZ strategy. 493 eyes with preoperative myopia ranging from -2.0 to -15.0 D and astigmatism ranging from 0.50 to 7.0 D were treated. Minimum follow-up time was one year. No topical corticosteroids were used postoperatively. Results. Mean sphere at 12 months for the -2.0 to -6.0 D eyes (group A) was +0.08 ± 0.89 D, for the -6.25 to -10.0 D eyes (group B) -0.67 ± 1.93 D, and for the -10.25 to -15.0 D eyes (group C) -2.25 ± 1.93 D. Mean cylinder at 12 months for group A was 0.97 D, for group B 0.45 D and for group C 1.37 D. Best corrected visual acuity was improved by one Snellen line in groups A and B, and remained unchanged in group C. Mean uncorrected visual acuity at 12 months was 0.76 ± 0.44 (decimal scale) in group A, 0.51 ± 0.41 in group B, and 0.38 ± 0.27 in group C. Maximum haze at 12 months was 1+ in groups A and B, 2+ in group C. Conclusions. These results are comparable or better than previous studies in which, however, steroids were needed. Tissue loss was reduced by 25% for equivalent OZ diameters. -------------------------------------------------------------------------------- Reaxys Database Information |