Penetrating corneal transplantation in the inbred rat: a new model

A model of orthotopic penetrating keratoplasty has been developed in the inbred rat using both avascular and prevascularized recipient beds. The surgical procedure is conventional and can be achieved with standard instrumentation. Isografts into avascular recipient beds (Fisher 344 into Fisher 344 strain combination) were successful and survived indefinitely with excellent corneal function judged either visually by clarity and lack of oedema, or histologically at autopsy. Allografts into avascular beds (DA into Fisher 344 strain combination) became cloudy and oedematous at a median of day 12 postgraft; 43% spontaneously recovered clarity while the remaining 57% remained opaque or became scarred. Penetrating grafts also were performed in eyes prevascularized by the placement of sutures approximately 3 weeks prior to transplantation. Most isografts into prevascularized and inflamed beds underwent a transient episode of oedema, which quickly resolved and was felt to result from postsurgical inflammation. All allografts into prevascularized beds became oedematous and cloudy; 76% went on to fail completely, while 24% cleared without treatment. End-point histology showed normal graft morphology in the isografts; failed allografts showed a picture consistent with immunologic rejection. The model, which allows corneal transplantation to be performed against a constant histocompatibility barrier, may be useful in studies of rejection.