The corneal host-graft function. Physiopathology of the scar.

The scar of penetrating homografts was studied in experimental grafts in rabbits and monkeys. The purpose of the study was to analyze the healing process in those grafts and correlate these findings to clinical situations of abnormal graft healing. Light, transmission and scanning electron microscopy were done for morphological studies. Radioautography with tritiated thymidine and S-35 sulfate was done to study cell repopulation and ground substance development in the scar. More than 50 p. 100 of cells present in the scar came from the host and lay down circular collagen fibers in the stroma and new Descemet's material at the endothelial level. Very tight (continuous) 10-0 nylon sutures produce necrosis of the edge of the wound and delay healing. From the morphological point of view it appears that very thin scars have less tensile strength than wider scars. These usually show circular and crisscrossing collagen fibers. Radial scars induced by silk sutures or through and through placed monofilament nylon add tensile strength to the wound.