Studies of Laser Subepithelial Keratomileusis (LASEK) using Leghorn Chick Eye

ABSTRACT

PURPOSE: Using the effect of 20% ethanol on Leghorn chick cornea, a suitable animal model for LASEK(Laser subepithelial keratomileusis) and effect on LASEK were evaluated. METHODS: Twenty Chick corneas were divided into 4 groups (n=5/group) to be exposed to 20% ethanol for 30 sec, 45 sec, 1 minute and 2 minutes respectively and changes were observed. Another 4 groups of Chick cornea, total of 20 (n=5/group) were prepared to perform nothing, PRK after mechanical or 20% ethanol-assisted debridement, or LASEK respectively and corneal changes were observed. RESULTS: Exposure of the corneal epithelium to 20% ethanol for more than 30 seconds allowed reproducible separation of epithelial flaps in Leghorn chick eyes. TUNEL staining of corneas obtained 4 hours after surgery revealed TUNEL-positive cells in the central superficial stroma and more abundantly in the peripheral superficial stroma around the epithelial flap margin and in the epithelial flap itself, particularly in the basal epithelial layer. Transmission electron microscopy showed similar evidence of apoptosis in the epithelium and anterior stroma. CONCLUSIONS: The Leghorn chick eye appears to be a reasonable model for LASEK surgery. Treatment with 20% ethanol for 30 seconds results in reproducible epithelial flap creation in the chick cornea and in relatively low levels of stromal and epithelial cell death after surgery.