Morphological and functional changes in the rat cornea with an ethanol-mediated epithelial flap

Area of Science:

• Ophthalmology
• Regenerative Medicine
• Corneal Biology

Background:

• Laser-assisted subepithelial keratectomy (LASEK) involves creating a corneal epithelial flap.
• Understanding the biological response to flap creation is crucial for optimizing surgical outcomes.
• Ethanol application is a common method for detaching the corneal epithelium.

Purpose of the Study:

• To investigate the morphologic and functional changes in the rat cornea following 20% ethanol-mediated epithelial flap creation.
• To compare the wound-healing response of ethanol-mediated flaps with mechanically scraped corneas.

Main Methods:

• Corneal epithelial flaps were created using 20% ethanol or mechanical scraping in Sprague-Dawley rats.
• Morphologic changes were assessed using light and transmission electron microscopy.
• Apoptosis and proliferation were evaluated using TUNEL assays and PCNA staining, respectively.
• Stromal keratocyte counts and gene expression (MMP-9, AQP5, MUC1) were analyzed.

Main Results:

• Ethanol-mediated flaps showed damaged basal cells and peak cell death/keratocyte loss at day 1, with proliferation and MMP-9 expression peaking from days 1-3.
• Mechanical scraping resulted in faster epithelial coverage by day 3, but earlier peak cell death and keratocyte loss.
• Hemidesmosomes were absent until day 1 and present by day 3 in both groups.
• SRY gene detection confirmed epithelial cell integration post-transplantation.

Conclusions:

• Ethanol-mediated flap creation leads to less keratocyte loss and a more gradual wound-healing process compared to mechanical scraping.
• The repositioned epithelial flap may provide a protective function for the underlying stroma.
• This rat model is suitable for studying wound healing after LASEK procedures.