CONSERVATIVE PHOTOREFRACTIVE KERATECTOMY FOR RESIDUAL MYOPIA FOLLOWING RADIAL KERATOTOMY

Objective: To evaluate the efficacy, predictability, stability and saf ety of a conservative approach to photorefractive keratectomy (PRK) (t reating only 60% to 70% of the residual myopia) for residual myopia fo llowing radial keratotomy (RK). Design: Case series. Setting: Laser ey e surgery centre in Windsor, Ont. Patients: Thirty-three eyes of 27 pa tients with an average age of 40.1 years who underwent PRK between Jan uary 1993 and July 1995, 12 months or more after RK. All were followed for at least 12 months after PRK. Outcome measures: Efficacy and safe ty were assessed by changes in the uncorrected and best corrected visu al acuity. Predictability was determined by the proximity of the final result to emmetropia. The stability of the refractive outcome was ass essed over the follow-up period. Results: At 12 months 12 eyes (36%) h ad 20/20 or better uncorrected visual acuity and 29 eyes (88%) had 20/ 40 or better uncorrected acuity. Twenty-seven eyes (82) were within 0. 50 D of emmetropia, and 30 eyes (91%) were within 1.00 D of emmetropia . There was a significant change in the mean postoperative spherical e quivalent between 1 and 3 months (p < 0.001); however, there was no si gnificant change after this time. Six eyes (18%) had a loss of 2 or mo re lines of best corrected visual acuity due to corneal haze; however, retreatment reduced this incidence-to 9% at 12 months. Conclusions: O ur results show that conservative PRK for residual myopia following RK is efficacious and predictable and produces stable results. However, the risk of postoperative haze reduces the safety of this procedure.