title: Histopathology of explanted collar button keratoprostheses: a clinicopathologic correlation.
abstract: OBJECTIVE
  To compare the histopathology of three PMMA collar button type keratoprosthesis (KPro)/corneal specimens, explanted due to various complications, with that from one KPro/corneal specimen taken postmortem from an otherwise "healthy" enucleated eye.
  
  
  METHODS
  Patient 1 (chemical injury) had no problems for 3 years after KPro placement; the entire eye was obtained postmortem. Patient 2 (repeated graft failures, nonautoimmune disease) developed an "unlaserable" retroprosthesis membrane 4 months after KPro placement. A new KPro was placed. Patient 3 [ocular cicatricial pemphigoid (OCP)] developed tissue melt at the KPro-cornea interface 7 months after KPro placement, and the KPro was replaced. Patient 4 (OCP) developed progressive corneal melt around the KPro 3.5 years after placement resulting in replacement. All KPro/cornea specimens were processed and sectioned for histology with the KPro in place.
  
  
  RESULTS
  All patients exhibited growth of corneal or conjunctival derived epithelium under the KPro front plate. In patients 1 and 2, no epithelial downgrowth was noted and the keratocyte density appeared normal with few inflammatory cells present. Dense fibrous tissue was present behind the KPro in patient 2. Patients 3 and 4 showed massive inflammatory cell infiltration and tissue necrosis with "melt" adjacent to the stem resulting in epithelial downgrowth.
  
  
  CONCLUSIONS
  Corneal inflammation and degradation after KPro placement correlate well with the preoperative diagnostic category. Patients with immune-related corneal surface disease can exhibit marked inflammatory responses leading to necrosis, stromal melting, and the formation of an epithelial fistula. In contrast, patients without autoimmune corneal disease demonstrate a remarkably noninflamed cornea with intact keratocytes and without epithelial ingrowth, commensurate with their clinical appearance.
authors.affiliation: Department of Ophthalmology, Harvard Medicial School, Massachusetts Eye and Ear Infirmary, Schepens Eye Research Institute, Boston, Massachusetts 02114, USA.
authors.forename: E J
authors.initials: EJ
authors.lastname: Dudenhoefer
authors.forename: M
authors.initials: M
authors.lastname: Nouri
authors.forename: I K
authors.initials: IK
authors.lastname: Gipson
authors.forename: K H
authors.initials: KH
authors.lastname: Baratz
authors.forename: A S
authors.initials: AS
authors.lastname: Tisdale
authors.forename: T P
authors.initials: TP
authors.lastname: Dryja
authors.forename: J C
authors.initials: JC
authors.lastname: Abad
authors.forename: C H
authors.initials: CH
authors.lastname: Dohlman
mesh_terms: D000368:Aged; D003228:Conjunctiva / Q000473:pathology; D003315:Cornea / Q000473:pathology* / Q000601:surgery*; D003316:Corneal Diseases / Q000601:surgery; D020878:Device Removal; D004848:Epithelium / Q000473:pathology; D019573:Epithelium, Corneal / Q000473:pathology; D005260:Female; D006801:Humans; D007634:Keratitis / Q000209:etiology / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009336:Necrosis; D019904:Polymethyl Methacrylate; D019736:Prostheses and Implants / Q000009:adverse effects*; D011474:Prosthesis Design; D012086:Reoperation
chemical_list: D019904:Polymethyl Methacrylate