Abstract
Purpose: :
Corneal collagen cross-linking (CXL) using riboflavin (Vitamin 2) and UVA irradiation is a non-invasive therapeutic option to treat progressive keratoconus. We previously reported that CXL procedure induces endothelial down-function causing both stromal edema and keratocyte death, in hens. To avoid direct radiation over endothelium, CXL procedure was tested over corneal flaps.
Methods: :
Corneal flaps (6,00 mm diameter, 70 µm thickness) were performed "in vivo" in both eyes of 30 adult hens, by means of a femtosecond laser. Right flaps, were UVA-irradiated (360-380 nm, 3 mW/cm2), during 30 minutes. A 0,1% riboflavin-20% dextran solution was administered 5 minutes prior irradiation and then every 5 minutes during the procedure. Left fellow corneas were used as control. Follow-up was carried out under a surgical microscope. Measurements of corneal thickness and transparency were assessed. At different time points (6 hours-6 months), animals were euthanized and corneas fixed for pathology. Both morphologic changes and cell biology parameters were evaluated by optical and fluorescence microscopy.
Results: :
The surgical procedure was successfully developed and characterized. No differences in either edema or corneal thickness were observed among right and left corneas. No sub-epithelial haze or endothelial damage was found by slip lamp in any cornea. A significant increase in the transmission of light was observed in CXL corneas respect to the controls (p<.01). Although keratocyte death was seen around the stromal bed and flap, differences were not significant between groups. No myofibroblast, no new collagen and no endothelial damage were found in any cornea.
Conclusions: :
A new way to perform CXL was developed in corneas of hens. This technique avoids some complications of the classical procedure. Further works will be necessary for clinical application.
Keywords: cornea: stroma and keratocytes • cornea: endothelium • wound healing