Eighteen-year follow-up of excimer laser photorefractive keratectomy

PURPOSE: To evaluate the long-term efficacy of photorefractive keratectomy (PRK). SETTING: University Hospital, London, United Kingdom. DESIGN: Prospective case series. METHODS: One eye of patients who had PRK 18 years previously was examined. All had myopic corrections with a 6.0 mm optical zone. RESULTS: Forty-six patients were examined. The mean preoperative spherical equivalent (SE) refractive error was -4.86 diopters (D) (range -2.75 to -7.375 D). The mean programmed correction was -4.43 D (range -2.50 to -7.00 D). Between 1 year and 18 years, the mean change in SE was -0.31 D (P = .06) and a significant increase in variance occurred (P < .002). The mean change in SE was -0.54 D in patients younger than 40 years at the time of correction (P<.02) and -0.05 D in patients older than 40 years (P =.9). The mean SE change was -0.40 D in women (P<.04) and -0.08 D in men (P = .8). The efficacy index was 0.58. The safety index was 0.998. The corrected distance visual acuity (CDVA) improved significantly from 1 to 18 years (P<.01). Ninety-six percent of corneas were clear at 18 years, with a reduction in haze scores (P<.001). There was no evidence of ectasia. CONCLUSIONS: A significant increase in myopic SE occurred between 1 year and 18 years after PRK in patients younger than 40 years and in women. Predictability decreased between 1 year and 18 years. The procedure was safe with no long-term complications. The CDVA and corneal transparency improved with time.