A primate model of human corneal transplantation

Human donor corneas were used for penetrating keratoplasty in one eye of each of 12 rhesus monkeys. In six animals, a 9.5-mm cornea was sutured into a 9.0-mm recipient bed by means of interrupted 10-0 nylon sutures. Six other animals received a 6.5-mm cornea in a 6.0-mm bed. Biomicroscopy, pachymetry, and specular microscopy revealed two distinct healing patterns. Of the six eyes receiving the smaller grafts, five showed prompt, stable clearing and thinning of the grafts with endothelial cell densities ranging from 850 to 1600 cells/mm2 Two of the six animals receiving larger grafts developed fibrinous reactions in the immediate postoperative period, and the grafts never cleared. Three showed a satisfactory early course, but after 10-16 days, developed endothelial keratic precipitates, anterior chamber reaction, and progressive graft edema. The sixth graft remained technically satisfactory 1 year later. This study indicates that the application of small human donor grafts in monkey eyes can provide a useful, clinical model for the future exploration of the response of human corneal transplants to materials such as epidermal growth factor and for the study of surgical manipulation of postkeratoplasty astigmatism.