Evaluation of photorefractive keratectomy retreatments after regressed myopic laser in situ keratomileusis

Abstract

Purpose To evaluate the results of photorefractive keratectomy (PRK) enhancements in eyes previously treated by myopic laser in situ keratomileusis (LASIK) showing an undercorrection due to either a refractive regression or a primary undercorrection, when an in-the-bed enhancement was not advisable because of residual stromal thickness limitations. Design Noncomparative, prospective, interventional case series. Participants Seventeen eyes of 17 patients previously treated by LASIK for a spherical equivalent (SE) correction of −8.125 to −12.50 diopters (D; mean, −9.45 ± 1.01 D), that after a follow-up of 6 to 14 months ended up with a refraction of −1.50 to −3.75 D (SE; mean, −2.48 ± 0.74 D). Intended flap thickness was 160 μm for all eyes. In all cases, the residual stromal bed under the flap was considered too thin (255–305 μm) to allow an in-the-bed enhancement without exceeding an assumed safety thickness limit (250 μm). Intervention Eyes were treated by PRK at least 6 months after LASIK. The PRK ablation parameters (diameter, attempted correction) were selected to avoid theoretical flap perforation. The deepest ablation was 60 μm, for a −3.75-D correction. We used a Bausch & Lomb 217 C excimer laser (Bausch & Lomb, Rochester, New York). Main outcome measures Refraction, uncorrected and best-corrected visual acuity (BCVA), slit-lamp evidence of corneal opacity or other visible complications, and corneal topography. Results Although the initial postoperative period was characterized by very satisfactory refractive results (mean SE error at 1 month, −0.04 ± 0.37 D; range, +0.75 to −0.625 D), during follow-up, a dense haze (grade 3 and 4) developed in 14 eyes (82.3%) that induced a further myopic regression (SE, −1.725 to −5.50 D; mean, −3.11 D) and BCVA loss (two to six lines). These 14 eyes underwent a further surgical treatment to remove the severe haze at 3 to 10 months after PRK. Conclusions Based on these results, we strongly advise against PRK as a possible option to correct eyes previously treated by myopic LASIK that resulted in an undercorrection.