Effect of mechanical vs dilute ethanol epithelial removal on keratocyte apoptosis and polymorphonuclear leukocyte migration.

Abstract

To investigate keratocyte apoptosis and polymorphonuclear (PMN) cell infiltration to the corneal stroma after mechanical epithelial scraping and chemical de-epithelialization with 18% ethanol solution. Twelve New Zealand Albino rabbits (24 eyes) were randomly divided into three groups. Group A was the control group with no epithelial removal. Group B underwent a 7.5-mm mechanical epithelial removal with a blunt spatula. Group C underwent 7.5-mm chemical de-epithelialization with 18% ethanol-balanced salt solution. Corneas were stained with terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick-end labeling (TUNEL) assay after 24 h. Only nuclear staining in keratocytes was counted. Polymorphonuclear (PMN) leukocyte densities were also assessed by light microscopy. Mechanical de-epithelialization (group B) and chemical de-epithelialization with 18% ethanol (group C) showed no difference in keratocyte apoptosis compared with the control group. There was also no difference between groups B and C. Group B showed no difference in PMN leukocyte counts compared with the control group. But the number of PMN leukocytes observed in group C was significantly higher than those encountered in the corneas of the control group (P < 0.05) and group B (P < 0.05). Dilute alcohol induces more PMN cell infiltration when compared with mechanical de-epithelialization although there is no difference in the apoptosis rates.