AUG 04, 2008
This study investigated the combined effects of ethanol and mitomycin C 0.02% (MMC) application on the corneal stroma of rabbits that underwent PRK. The study's findings indicated that ethanol application for epithelial removal during PRK seemed to produce a synergistic effect with MMC, resulting in fewer keratocytes in the anterior stroma of rabbit corneas than in corneas treated with MMC alone after PRK.
Twenty-four eyes of 24 rabbits underwent PRK to correct 9 D of myopia, after which MMC was applied for 12 seconds. Prior to removal of the epithelium, 20% ethanol solution was applied for 30 seconds to 12 eyes. The epithelium was manually removed from the remaining eyes without the use of ethanol. Twelve rabbits were sacrificed after four hours and after four weeks. Immunohistochemistry was performed with the TUNEL assay, alpha-smooth muscle actin (alpha-SMA) and DAPI.
Significantly more TUNEL-positive cells were found in the ethanol-treated group compared with the mechanical debridement group four hours after surgery. No significant difference in the number of alpha-SMA-positive cells was detected between the two groups four weeks after surgery. However, the loss of keratocyte density in the anterior stroma was significantly more pronounced in the ethanol group compared with the mechanical debridement group.
Based on the study's results and the possibility of long-term diminished keratocyte density in the anterior stroma following prophylactic MMC treatment, the study's authors suggested that the epithelium be manually removed during PRK instead of using ethanol for the procedure. While the use of MMC prophylactically in conjunction with PRK has become popular for preventing corneal haze, the possible synergistic effect of ethanol with MMC may further compromise stromal keratocyte density and increase the risk of long-term corneal complications, they said.
Dr. Stahl is a consultant for AcuFocus, Inc.