title: [Biological corneal replacement--an alternative to keratoplasty and keratoprosthesis? A pilot study with heterologous hyaline cartilage in the rabbit model].
abstract: BACKGROUND
  In patients with corneal opacity caused by diseases like okular pemphigoid, Stevens-Johnson-Syndrome or burns, visual rehabilitation can only be achieved with keratoplasty or keratoprosthesis. The first has generally a poor prognosis in these circumstances, and the latter bears several problems in the postoperative course as well. A biological, corneal replacement could possibly combine the advantages offered by keratoplasty (no interaction between host tissue and plastic) and keratoprosthesis (more permanent transparency). Theoretical considerations and practical experience suggest that the best candidate would be hyaline cartilage.
  
  
  METHODS
  Bovine sterni were used to obtain circular cartilage slices which were approximately 60 microns thick, having a diameter of approximately 6 mm. These slices were implanted 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 vessels could be visualized. Connective tissue served to bind the host cornea to the cartilage, but did not infiltrate the cartilage. Perforation was observed in 3 animals. The extent of epithelialization of the cartilage slices ranged form ca. 30% to 95%. None of the animals exhibited an intraocular inflammation. The cartilage did not proliferate and remained avascular. Secondary intraocular changes, with the exception of anterior synechiae, could not be detected.
  
  
  CONCLUSIONS
  A tissue for biological corneal replacement has to fulfill many requirements which to a certain extent can be achieved with the use of hyaline cartilage. Despite numerous, unsolved problems, a biological corneal replacement as an alternative to keratoplasty and keratoprosthesis in cases of corneal blindness does not seem out of imagination.
mesh_terms: D000818:Animals; D001705:Bioprosthesis; D002356:Cartilage / Q000637:transplantation; D002417:Cattle; D003315:Cornea / Q000473:pathology; D003318:Corneal Opacity / Q000209:etiology / Q000601:surgery*; D016039:Corneal Transplantation; D011474:Prosthesis Design; D011817:Rabbits; D014945:Wound Healing / Q000502:physiology
vernacular_title: Biologischer Hornhautersatz--Alternative zu Keratoplastik und Keratoprothese? Eine Pilotstudie mit heterologem, hyalinem Knorpel am Kaninchenmodell.