Abstract
Abstract: :
Purpose: To determine the epithelial growth patterns after different techniques of experimental human amniotic membrane (AM) transplantation in rabbit corneal ulcers. Methods: Standardized corneal ulcers (150 µm deep; 6 mm diameter) were induced with the 2.94 µm Er:YAG laser in 14 rabbits, which were subsequently operated with three different techniques of AM transplantation: patch (onlay = single layer of AM from limbus to limbus), graft (inlay = one layer of AM inside the borders of epithelial debridement around the ulcer) and sandwich (inlay + onlay = combination of single graft and patch). After 3, 7 or 21 days the eyes were enucleated and fixed in a buffered 10% paraformaldehyde solution. Serial sections stained with periodic acid-Schiff (PAS) and Masson's trichrome were analyzed by light microscopy. Normal human AM was used for comparison. Time-course of reepithelialization was compared to four rabbit corneal ulcers without AM. Results: After 3 days the central ulcer was partly and after 7 days completely covered by rabbit corneal epithelium independent of the surgical technique used compared to 15 - 17 days in the controls without AM. Rabbit epithelium grew onto and below the graft, and recovered the normal rabbit corneal epithelial phenotype already beginning after one week. Using a patch the epithelium grew on the corneal stroma below the AM. Using the sandwich technique, corneal epithelial growth on top of the graft seemed to be promoted. The patch was gone after one week in all eyes. AM basement membrane and dense AM subepithelial stromal network of grafts partly disintegrated during the first 3 weeks. Conclusion: Human amniotic membrane transplantation facilitates quick reepithelialization of rabbit corneal ulcers. While a graft may be integrated primarily as a new basal membrane, the patch seems to promote the epithelial growth on the denuded corneal stroma. AM constituents rapidly disintegrated after transplantation.
Keywords: 372 cornea: epithelium • 631 wound healing • 607 transplantation