BIOLOGICAL CORNEAL REPLACEMENT - ALTERNAT IVE TO KERATOPLASTY AND KERATOPROSTHESIS - A PILOT-STUDY WITH HETEROLOGOUS HYALINE CARTILAGE IN THE RABBIT MODEL

Background In patients with corneal opacity caused by diseases like ok ular pemphigoid, Stevens-Johnson-Syndrome or burns, visual rehabilitat ion can only be achieved with keratoplasty or keratoprosthesis. The fi rst has generally a poor prognosis in these circumstances, and the lat ter bears several problems in the postoperative course as well. A biol ogical, corneal replacement could possibly combine the advantages offe red by keratoplasty (no interaction between host tissue and plastic) a nd keratoplasty is (more permanent transparency). Theoretical consider ations and practical experience suggest that the best candidate would be hyaline cartilage. Material and methods Bovine sterni were used to obtain circular cartilage slices which were approximately 60 mu m thic k, having a diameter of approximately 6 mm. These slices were implante d in one eye each of 4 rabbits instead of the natural cornea. The eyes were enucleated after 8 to 29 days. Results The cartilage remained so transparent that the iris and to a certain extent the fundus blood ve ssels could be visualized. Connective tissue served to bind the host c ornea to the cartilage, but did not infiltrate the cartilage. Perforat ion was observed in 3 animals. The extent of epithelialization of the cartilage slices ranged form ca. 30% to 95%. None of the animals exhib ited an intraocular inflammation. The cartilage did not proliferate an d remained avascular. Secondary intraocular changes, with the exceptio n of anterior synechiae, could not be detected. Conclusions A tissue f or biological corneal replacement has to fullfill many requirements wh ich to a certain extent can be achieved with the use of hyaline cartil age. Despite numerous, unsolved problems, a biological corneal replace ment as an alternative to keratoplasty and keratoprosthesis in cases o f corneal blindness does not seem out of imagination.