Photorefractive keratectomy in high myopic defects with or without intraoperative mitomycin C: 1-year results

PURPOSE. To study the results of the prophylactic use of mitomycin C (MMC) to reduce haze formation and refractive regression after excimer laser photorefractive keratectomy (PRK) for high myopic defects (> 5 diopters). METHODS. Prospective, consecutive, observational study. A total of 124 eyes of 62 patients were divided into two groups of 31 patients, 62 eyes each (Groups A and B). Only Group A was treated with MMC 0.02%. The data of the two groups of eyes, related to the best-corrected visual acuity (BCVA), to the difference of refraction pre- and post-treatment, and to the corneal haze, were analyzed through combined permutation tests by using the NPC Test software. RESULTS. BCVA of Group A, 1 year after treatment, was better than that of the control Group B (one-sided p value = 0.013): Group A - 3 eyes (4.8%) had a loss of a decimal fraction and no eyes > 1; Group B - 13 eyes (20.9%) had a loss of a decimal fraction and 1 eye (1.6%) of 2. There was a smaller difference between attempted and achieved SE correction in Group A with respect to Group B (one-sided p value = 0.068): Group A - 43 eyes (69.3%) within +/- 0.50 D; Group B - 31 eyes (50%) within +/- 0.50 D. there was a smaller incidence of corneal haze in the group for which MMC was used (one-sided p value = 0,005). CONCLUSIONS. In this study, the application of MMC 0.02% solution immediately after PRK produced lower haze rates and had better predictability and improved efficacy 1 year after treatment.