Delayed epithelial healing following photorefractive keratectomy with mitomycin C treatment

Purpose: To evaluate the epithelial healing following photorefractive keratectomy (PRK) with mitomycin C (MMC) 0.02%. Methods: A total of 1520 eyes of 760 patients with myopia with spherical equivalent between -1.5 and -8.0 dioptres underwent PRK during 2004-2008. The epithelium was removed mechanically, and laser ablation was followed by topical application of MMC (0.02%) for 20 seconds. A therapeutic contact lens (TCL), kept in 4°C, was fitted and worn until complete epithelialization. Antibiotic, steroid and diclofenac drops were instilled during the healing phase. Steroid drops were used for 6-8 weeks and gradually reduced. The results were compared with a retrospective analysis of 500 myopic eyes which underwent PRK without MMC therapy during 2002-2004. Results: In 30 MMC treated eyes (2%), epithelial healing was delayed with a stellate defect which healed after 12-14 days. Another fifteen eyes (1%) revealed loose midperipheral epithelium and complete epithelialization took 10-14 days after scraping. Two of these eyes developed recurrent erosion treated by scraping and TCL. Seven eyes (0.5%) revealed delayed healing with paracentral epithelial plaques which were scraped and complete healing took 12-14 days. No final haze was found in the MMC-treated eyes. In comparison, only 0.8% of the eyes which had undergone PRK without MMC revealed epithelial problems. Haze was found in 8% of these eyes. A statistically significant difference was found between the rate of epithelial problems of the two groups (p ≤ 0.002). Conclusions: MMC (0.02%) applied for 20 seconds post-PRK was found to delay epithelial wound healing up to 14 days in 3.5% of patients with myopia compared to 0.8% of PRK eyes without MMC application. Final haze was not found despite delayed epithelialization because of MMC treatment.