The effect of phenylephrine on the cornea.

Rabbit corneas were treated with three drops of phenylephrine hydrochloride with the epithelium intact or denuded. Corneal thickness was measured before and after drug treatment, and at various times after treatment the corneas were fixed for scanning and transmission electron microscopic observation. The results of this study show that phenylephrine caused a dramatic increase in corneal thickness (drug-induced edema) and cellular vacuolation within the keratocytes and endothelial cells in the corneas without the epithelium. Corneal thickness did not change and the ultrastructural changes were minimal following drug application in those corneas with the epithelium intact. Results of this study also suggest that phenylephrine has a cytotoxic effect on the corneal endothelium and keratocytes when used in corneas where the epithelium has been removed. In coreas with intact epithelium, the damage was less severe and limited to the epithelium.