Collagens and proteoglycans of the cornea: importance in transparency and visual disorders
To investigate the expression of extracellular matrix collagens and their relationship to corneal opacities after implantation of epithelial cells in the flap–stroma corneal interface. A corneal flap was made on rabbit eyes, and epithelial cells, mechanically scraped from tissue surrounding the flap, were implanted beneath the flap. The corneas were harvested 1, 3, 7, and 30 days following surgery. Histological and immunohistochemical examinations were performed. The expression and localization of types I, III, and IV collagens and gelatinase A were determined. Slit-lamp examination showed corneal opacity in the area where the epithelial cells were implanted. Histological study revealed clusters of epithelial cells between the flap and stromal interface. One week and 1 month after the implantation, intense immunoreactivity for collagen type IV was detected at the perimeters of the intrastromal epithelial islands, but not in the interface outside the implanted epithelial cells. Weak positive staining for gelatinase A was detected in the implanted epithelial cells and surrounding keratocytes. The heavy deposition of collagen type IV surrounding the implanted epithelial cells indicated that it might be an essential component of the interface haze observed in patients following laser in situ Keratomileusis. Gelatinase A may also play a role in the regulation of stromal remodeling after epithelial ingrowth.