The Effect of Ethanol Treatment on Rabbit Corneal Epithelium: A Histological Study

Abstract

Abstract: : Purpose: Laser Epithelial Keratomileusis (LASEK) is a refractive surgical technique which involves creating a corneal epithelial flap by exposure of the corneal surface to ethanol for a brief period of time. This complete chemical debridement of corneal epithelial cells with ethanol has yet to be studied in depth. Here we assess the effect of corneal debridement with ethanol (25%) on rabbit corneal epithelium by electron microscopy. Methods: Rabbit corneas were de-epithelialized by the application of ethanol (25%) for 3 minutes, after which they were thoroughly washed with balanced saline solution. A hinged epithelial flap was created and repositioned one minute later. Bandage contact lenses were placed on the eyes of each rabbit to keep the ocular flap in place, and topical Ofloxacin and Betamethasone were applied. In no cases were epithelial defects visible before placement of the bandage contact lens. Ten corneas were evaluated by scanning and transmission electron microscopy immediately after exposed to ethanol and at time 0, 1, 3 and 7 days thereafter. Ultrastructural studies were performed to assess the histological change of the cornea at various times after the ethanol procedure. Results: Corneas treated with ethanol showed a decrease in microvilli along with breaks in intercellular junctions, epithelial cell edema and damage of the basal membrane. These toxic changes receded after 24 hours and rapidly improved over the following week. Wing cells showed no damage at any stage. Conclusions: Although ethanol seems to have a toxic effect on rabbit epithelial cells, this effect does not persist over time and the first recovery signs are observed as soon as 24 hours after ethanol debridement. Complete recovery occurs within the following week. The path by which ethanol reaches the central basal membrane seems to be centripetally from around the cut and down through the basal membrane, leaving the wing cells intact and allowing epithelial separation at the basement membrane.

Keywords: cornea: epithelium • refractive surgery: other technologies • microscopy: electron microscopy