MULTICENTER TRIAL OF PHOTOREFRACTIVE KERATECTOMY FOR RESIDUAL MYOPIA AFTER PREVIOUS OCULAR SURGERY

Purpose: The Summit Therapeutic Refractive Clinical Trial is a nine-ce nter prospective, nonrandomized, self-controlled trial to assess the e fficacy, stability, and safety of using a standardized technique of ex cimer laser photorefractive keratectomy (PRK) to correct residual myop ia in eyes with previous refractive surgery or cataract surgery. Patie nts and Methods: Eligible eyes with a mean residual myopia of -3.7 +/- 1.8 diopters (D) (range, -0.63 to -11.00 D) underwent PRK with a 193- nm excimer laser for myopic corrections between -1.50 and -7.50 D, Sta ndardized settings were used for the ablation zone, ablation rate, rep etition rate, and fluence. One hundred seven of the first 114 treated eyes were examined 1 year after PRK, with 98% of eyes having had refra ctive keratotomy and 2% having had cataract surgery. Results: One year postoperatively, the mean manifest spherical equivalent refraction wa s -0.6 +/- 1.4 D (range, -6.50 to 2.50 D); 63% of eyes were within +/- 1.00 D of the attempted correction; and uncorrected visual acuity was 20/40 or better in 74% of eyes. Twenty-nine percent of eyes lost two or more Snellen lines of best-corrected visual acuity, and central cor neal haze was moderate or severe in 8% of eyes. Conclusion: Excimer la ser PRK is effective in reducing residual myopia after previous refrac tive and cataract surgery. However, it is less accurate than PRK in ey es that did not undergo surgery and is more likely to cause a loss of best-corrected visual acuity 1 year after treatment.