Inhibition of vascularization in rabbit corneas by heparin: cortisone pellets

The purpose of this work was to study the effectiveness of heparin plus cortisone, and of cortisone alone in control of corneal vascularization in rabbit eyes. Corneal vascularization was induced by de-epithelialization of the cornea and limbus and part of the bulbar conjunctiva with concurrent trephination and excision of a central 2-mm diameter corneal button. Inhibition of vascularization by polymer pellets impregnated with heparin (Panheprin, Abbott Laboratories; Chicago, IL) and cortisone, or neither drug was studied by implanting the pellets into the eyes at the time of injury and following the eye clinically and histologically. Wounded corneas with empty pellets developed vascularization extending from the limbus to the central cornea within 3 wk (n = 10). In other wounded eyes, heparin:cortisone pellets prevented vascularization (n = 10) while cortisone pellets slowed, but did not totally inhibit vascularization (n = 6). In other eyes, clear autografts were transplanted into vascularized eyes; and the ability of the drug-impregnated pellets to inhibit grafts vascularization was evaluated. In eyes with heparin:cortisone pellets inserted into the donor button at the time of keratoplasty, the autografts remained clear for at least 6 wk (n = 10) but subsequently vascularized if the sutures were not removed, while cortisone pellets slowed but did not block vascularization (n = 6). If heparin:cortisone pellets were inserted into the vascularized host tissue, rather than into the donor button, vascularization of the graft occurred (n = 6). Thus, heparin (Panheprin, Abbott Laboratories; Chicago IL) plus cortisone inhibited vascularization in rabbit cornea in the models studied: The effect of other commercially available heparins remains to be studied.