Epithelial removal with the excimer laser (laser-scrape) in photorefractive keratectomy retreatment

Abstract

Objectives To retrospectively evaluate refractive and topographic outcomes after excimer laser photorefractive keratectomy (PRK) retreatment using the laser-scrape technique for epithelial removal. Design Retrospective clinical study. Participants Thirty eyes of patients who had PRK retreatment for undercorrection after primary PRK were examined. Intervention The PRK retreatment was performed using a laser-scrape technique in which the excimer laser was used to remove the majority of the epithelium overlying the anterior stromal surface before additional PRK ablation. Main outcome measures Uncorrected visual acuity, best-corrected visual acuity (BCVA), surface regularity index (SRI), and surface asymmetry index were measured. Results Primary PRK was performed for myopia of −5.1 ± 1.7 diopters (range, −1.1 to −7.5 diopters). Mean spherical equivalent (SE) was −1.3 ± 0.4 diopters (range, −0.6 to −2.0 diopters) before retreatment. Mean SE 6 months after retreatment decreased to +0.1 ± 0.4 diopter (range, +1.25 to −0.75 diopters; P < 0.0001). Four eyes (15%) were more than +0.5 diopter overcorrected at 6 months. Ninety-six percent of eyes achieved mean SE within ±1 diopter and 77% within ±0.5 diopter of emmetropia after retreatment. Visual acuity improved significantly 6 months after reablation ( P < 0.0001) with 100% 20/40 or better and 73% 20/25 or better without correction. Final BCVA also improved compared with before retreatment ( P = 0.02). Twelve eyes gained 1 line of BCVA and no eye lost more than 1 line of BCVA. The SRI before retreatment was 0.6 ± 0.3 (range, 0.0–0.9) and remained the same 0.6 ± 0.2 (range, 0.1–1.0; P = 0.8), 6 months after retreatment. Conclusion Excimer laser PRK retreatment using the laser-scrape technique for epithelial removal is an accurate and safe procedure for treating undercorrection of eyes after PRK for low-to-moderate myopia.