title: Surface epithelialization of the type I Boston keratoprosthesis front plate: immunohistochemical and high-definition optical coherence tomography characterization.
abstract: BACKGROUND
  The aim of this work is to characterize a transparent tissue layer partially covering the anterior surface of the type I Boston permanent keratoprosthesis front plate in four patients.
  
  
  METHODS
  The tissue over the front plate was easily scrolled back as a single transparent layer using a sponge. In two cases, histopathologic analysis was undertaken and immunofluorescent staining with a cytokeratin 3-specific antibody was performed. The relationship of the tissue to the keratoprosthesis device was further characterized using spectral domain high-definition optical coherence tomography (HD-OCT).
  
  
  RESULTS
  Histopathologic analysis revealed the tissue to be non-keratinized squamous epithelium. No goblet cells were seen, suggesting the cells were of corneal, and not conjunctival, epithelial origin. Immunofluorescent staining of all cells was positive for cytokeratin 3, a protein strongly associated with corneal epithelium. The tissue was easily discerned by HD-OCT and was of substantial thickness near the external junction between the keratoprosthesis device and the carrier corneal tissue. In three cases, visual acuity was unaffected by the presence or absence of this tissue. In one case, a prominent tissue margin temporarily obscured the visual axis and reduced visual acuity; this resolved with mechanical central debridement and has not recurred.
  
  
  CONCLUSIONS
  The transparent tissue layer covering the anterior surface of the type I Boston keratoprosthesis front plate was found to represent non-keratinized squamous epithelium, most likely of corneal epithelial origin. This potentially represents a further step in bio-integration of the keratoprosthesis device. In particular, epithelial coverage of the critical junction between the device and the carrier corneal tissue might serve an important barrier function and further reduce the incidence of infection and extrusion of the type I Boston permanent keratoprosthesis.
authors.affiliation: Department of Ophthalmology, Weill Cornell Medical College, New York-Presbyterian Hospital, 1305 York Avenue, 12th Floor, New York, NY 10021, USA.
authors.forename: Lee
authors.initials: L
authors.lastname: Kiang
authors.forename: Mark I
authors.initials: MI
authors.lastname: Rosenblatt
authors.forename: Rachel
authors.initials: R
authors.lastname: Sartaj
authors.forename: Ana G Alzaga
authors.initials: AG
authors.lastname: Fernandez
authors.forename: Szilard
authors.initials: S
authors.lastname: Kiss
authors.forename: Nathan M
authors.initials: NM
authors.lastname: Radcliffe
authors.forename: Donald J
authors.initials: DJ
authors.lastname: D'Amico
authors.forename: Kimberly C
authors.initials: KC
authors.lastname: Sippel
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001187:Artificial Organs; D003315:Cornea; D019573:Epithelium, Corneal / Q000378:metabolism / Q000473:pathology*; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D053558:Keratin-3 / Q000378:metabolism; D008297:Male; D011183:Postoperative Complications; D019736:Prostheses and Implants; D019919:Prosthesis Implantation; D012189:Retrospective Studies; D041623:Tomography, Optical Coherence
chemical_list: D053558:Keratin-3