Effect of Mitomycin C to Inhibit Corneal Haze Formation after Photorefractive Keratectomy for High Myopia

Purpose: To evaluate the safety and results of the prophylactic use of 0.02% mitomycin C (MMC) to inhibit haze formation after excimer laser photorefractive keratectomy (PRK) for high myopia in eyes that were not good candidates for laser in situ keratomileusis (LASIK) because of inadequate corneal thickness. Methods: On thirty eyes with high myopia (-6.0 to -10.13 diopters), PRK with intraoperative topical 0.02% MMC application was performed. Visual acuity, refraction, keratometry, corneal haze, central corneal thickness, corneal endothelium, repair of corneal epithelium, and other complications were evaluated for 1 year. Results: No eyes showed any BCVA loss, and some even presented a BCVA increase, except in one case: one eye had lost a line 1 year after PRK. At 1 year after surgery, the spherical equivalent was within ±0.5 D of the desired refraction in 73.33% of the cases, and 86.67% were within ±1.0 D of the intended refraction. At 3 months after surgery, the mean corneal haze scale stabilized at about 0.22, and decreased further thereafter. Central corneal thickness increased steadily postoperatively, whereas endothelial density decreased significantly, however, the percentage of hexagonal cells and coefficient of variation in cell area showed no change. Epithelial regeneration was complete within 4 days, and there were no other complications. Conclusions: The prophylactic use of a 0.02% MMC applied intraoperatively after PRK produced lower haze rates and a better visual outcome. But, due to the decrease in endothelial cell density, the safety of MMC can be determined only after long-term observation.