PHOTOREFRACTIVE KERATECTOMY FOR RESIDUAL MYOPIA AFTER RADIAL KERATOTOMY

Purpose: To evaluate the visual outcomes in patients having photorefra ctive keratectomy (PRK) to correct residual myopia after radial kerato tomy (RK). Setting: Nine refractive surgery centers in the United Stal es and one in South Korea. Methods: This retrospective analysis compri sed 38 eyes of 32 patients treated with PRK after RK and followed for 12 months. Analysis was based on pre-RK and pre-PRK refraction as well as response to RK (pre-RK minus pre-PRK refractions). Results: Mean p re-RK and pre-PRK refractions were -8.11 diopters (D) +/- 2.92 (SD) an d -4.28 +/- 2.08 D, respectively. One month after PRK, mean refraction was +0.42 +/- 1.56 D and regressed to -0.95 +/- 1.24 D at 12 months. At 12 months, 65% of eyes had an uncorrected visual acuity of 20/40 or worse, and 11.1% lost 2 or more lines of best corrected acuity. Of ey es with an original error of -6.00 or less, 81.8% were within +/-1.00 D of intended correction at 12 months and of those with an original er ror of -9.12 to -20.00 D, 50.0% (P = .004). All eyes with residual (pr e-PRK) errors of -3.00 D or less and 42.9% with a residual error of -6 .12 to -9.00 D were within +/-1.00 D of intended correction (P = .07). There were no statistically significant differences in the response t o PRK between eyes that had an RK response of 0 to 3.00, 3.12 to 6.00, or 6.12 to 12.00 D. Conclusion: Patients with lower original and resi dual myopia achieved better visual outcomes after PRK than those with higher myopia. The amount of myopic correction achieved using RK was n ot predictive of the amount of myopic correction using PRK.