Prospective study of photorefractive keratectomy for myopia using the VISX StarS2 excimer laser system.

摘要

PURPOSE: To evaluate the safety, efficacy, and predictability of excimer laser photorefractive keratectomy (PRK) for compound myopic astigmatism using the VISX StarS2 excimer laser system with international version 3.1 software. METHODS: We report a prospective consecutive study of myopic excimer laser PRK, performed in a multi-surgeon environment with 200 eyes of 117 patients, to correct naturally occurring compound myopic astigmatism of between -0.50 to -5.90 D manifest refractive sphere and up to -3.50 D manifest refractive astigmatism. Patients were assessed prior to surgery and at 1, 3, 6, and 12 months after treatment. RESULTS: One hundred and ninety-eight of 200 treatments (99%) were reviewed 1 year after surgery; 193 of 198 eyes (97%) achieved 20/40 or better uncorrected visual acuity and 163 of 198 eyes (82%) achieved 20/20 or better. One eye lost two lines of Snellen visual acuity assessed at 12 months but recovered acuity when assessed at 18 months. Mean spherical equivalent corneal plane power was reduced from -3.50 to +0.90 D 1 month after treatment and 0 D at 12 months (SD 0.67 D). Three eyes of three patients underwent further treatment, two with LASIK and one with PRK for residual refractive error. Refractive astigmatism of >1.00 D was reduced from a mean -1.70 to -0.70 D at 1 year after treatment. Vector magnitude was 79% of that intended and mean vector axis error (absolute) was 8.5 degrees. No eye had a severe haze response. Pelli-Robson contrast acuity was significantly reduced after treatment from a mean 1.72 D preoperatively to 1.63 D at 12 months (P<.01). CONCLUSIONS: PRK for myopia using the VISX StarS2 excimer laser system was effective in the treatment of low myopic astigmatism, although there was a significant reduction in Pelli-Robson contrast sensitivity.