The Change of Cornea after 20% Ethanol Treatment in LASEK

ABSTRACT

PURPOSE: Recently, 20% ethanol has been used to make a corneal epithelial flap effectively. We investigated the toxicity of ethanol using the corneal epithelial cell line and rat cornea. METHODS: Cultured corneal epithelial cells were exposed to different concentrations (5~60%) of ethanol for different exposure time (20~120 seconds). And then cell viability was measured with MTT assay. In vivo, rat central corneas (3mm in diameter) were exposed to 20% ethanol for 30 seconds. The eyes were enucleated, fixed and processed for light microscopy (LM) and transmission electron microscopy (TEM) at indicated interval (0, 4, 8 and 12hours, 1, 3 and 7 days). TUNEL assay was used to detect apoptotic cells. RESULTS: Cultured epithelial cells showed survival rate of over 50% in ethanol concentration of below 20% (76.2 +/- 7.4%) and exposure time of below 1 minute (54.8 +/- 6.5%). In vivo experiment, after 20% ethanol exposure for 30 seconds, vacuoles were detected in the nuclei of epithelial cells and gradually disappeared. Hemidesmosomes were detected in the basement membrane at all times. TUNEL positive cells were detected in the epithelial layer and anterior stroma at the edge until 8hrs. CONCLUSIONS: Our results showed 20% ethanol exposure for 30 seconds did not seems to induce significant damage to the cornea. Corneal epithelial damage could occur by physical force during epithelial flap making.