Long-term outcomes of photorefractive keratectomy for low to high myopia: 13 to 19 years of follow-up.

PURPOSE To evaluate long-term outcomes after photorefractive keratectomy (PRK). METHODS A retrospective follow-up study of patients who received PRK at 5.0- to 6.5-mm optical zones, using the Summit broad beam excimer laser (Summit Technology, Inc., Waltham, MA) at Odense University Hospital, Odense, Denmark, between 1992 and 1998. One randomly selected eye of each patient was used in the statistical analyses. Re-treated eyes were excluded. RESULTS One hundred sixty eyes were included. Mean follow-up time was 16 years (range: 13 to 19 years). Mean preoperative spherical equivalent was -4.84 ± 2.95 diopters (D) (range: -20.25 to -1.25 D). At last follow-up examination, achieved refraction was -1.00 ± 1.56 D (range: -10.75 to +1.00 D) from attempted refraction, and the change in mean refractive error from 6 months postoperatively was less than 1.00 D. Results from a subgroup of unilateral treated patients indicated that myopic progression was the main reason for the residual refractive error. For eyes with low myopia (n = 124), the proportion of eyes within ± 1.0 D of attempted refraction was 72%, and for eyes with high myopia (-6.00 D or more, n = 36) it was 47%. Forty-five percent had uncorrected distance visual acuity of 20/20 or better at last follow-up examination. Three eyes (2%) lost two or more lines and 13 eyes (8%) gained two or more lines of corrected distance visual acuity. Fourteen percent had haze (grade 0.5 to 2). Eighty-one percent were satisfied with the surgery. CONCLUSION PRK for low degrees of myopia seemed safe and effective up to 19 years after surgery with conventional broad beam laser ablation. Refractive predictability was significantly lower and the occurrence of haze was higher in eyes with high myopia.