Results of photorefractive keratectomy with mitomycin C for high myopia after 4 years

This study assessed the long-term results of photorefractive keratectomy (PRK) with mitomycin C in high myopia (.7 diopter). In this retrospective study, visual acuity, refractive error, pachymetry, topography, contrast sensitivity, corneal haze safety, predictability and complications (with emphasis on ectasia) of 37 high myopic patients (72 eyes) who had PRK surgery with mitomycin C in the last 10 to 40 months were assessed. The exclusion criteria included previous ocular surgery other than LASIK, current ocular disease and any systemic illness. The mean follow up period was 27.2 ± 7.9 months. The spherical equivalent error was significantly reduced, from a mean of -9.10 ± 2.12 diopters (D) (range of -7 to -18.25 D) before PRK to a mean of -1.81 ± 1.57 D (range of - 8.5 to 0 D) after (P = 0.001). Postoperatively, 34.72% of eyes were within ± 0.5 D of attempted correction and 58.33% within ±1 D and 84.72% within ±2 D. 80.5% of eyes had a vision of 20/40 or better. Best corrected visual acuity (BCVA) was unchanged or improved in 93.05%. The safety index was 0.96 [the ratio of mean postoperative BCVA (0.84) to mean preoperative BCVA (0.87)] and efficacy index was 0.8 [the ratio of mean postoperative uncorrected visual acuity (0.7) to mean preoperative BCVA (0.87)]. Corneal haze formation was seen in 5 patients (6.9%) with grade +1. The minimum stromal residual bed was 400 Cm. No eyes had progressive corneal ectasias at the time of post-op control. The topical intraoperative application of 0.02% mitomycin C can reduce haze formation in highly myopic eyes undergoing PRK. Predictability of refractive results, however, was poor.