MULTICENTER STUDY OF PHOTOREFRACTIVE KERATECTOMY FOR MYOPIA OF 6.00 TO 8.00 DIOPTERS

PURPOSE: To summarize the initial results of excimer laser photorefrac tive keratectomy (PRK) on 89 eyes of 80 patients with moderate myopia (myopia of - 6.00 to - 8.00 diopters [D]; mean - 6.98 +/- 0.90 D) at n ine investigational sites. METHODS: All treatments used an argon fluor ide excimer laser (VISX, Inc, Santa Clara, Calif) using standard setti ngs. Sixty eyes received single-zone 6.0-millimeter ablations and 29 e yes received two-zone ablations. Follow up ranged from 1 month (n = 89 ) to 6 months (n = 46). RESULTS: At 3 months, uncorrected visual acuit y measured 20/40 or better in 75% and 20/20 or better in 18%; 78% were within +/- 1.00 D of intended correction, 38% were within +/- 0.50 D, and 9% lost two or more lines of spectacle-corrected visual acuity. A t 6 months, uncorrected visual acuity measured 20/40 or better in 74% and 20/20 or better in 17%; 67% were within 1.00 D of intended correct ion, 38% within 0.50 D, and 2% (1/46) lost two lines of spectacle corr ected visual acuity. CONCLUSIONS: PRK for moderate myopia with large d iameter ablation zones appears safe and more predictable than that don e using smaller ablation zone diameters. Longer follow up is needed to better define stability, the effects of postoperative corticosteroids , and the use of single- versus double-zone ablations.