title: The Boston type I keratoprosthesis: improving outcomes and expanding indications.
abstract: OBJECTIVE
  To report the usefulness of the Boston type I keratoprosthesis (Massachusetts Eye and Ear Infirmary, Boston, MA) in the management of corneal opacification, corneal limbal stem cell failure, or both in a large single-surgeon series.
  
  
  METHODS
  Retrospective review of consecutive clinical case series.
  
  
  METHODS
  All patients undergoing keratoprosthesis implantation by a single surgeon (AJA) between May 1, 2004, and May 31, 2008.
  
  
  METHODS
  Data were collected regarding the preoperative characteristics of each eye undergoing keratoprosthesis implantation, the surgical procedure(s) performed, and the postoperative course. Statistical analysis was performed to identify factors influencing the incidence and severity of postoperative complications.
  
  
  METHODS
  Interval visual acuities, keratoprosthesis retention, and significant postoperative complications.
  
  
  RESULTS
  Fifty-seven keratoprosthesis procedures were performed in 50 eyes of 49 patients. The primary indication for surgery was repeat corneal transplantation failure (68%), although no prior corneal surgery had been performed in 16% of eyes. Preoperative visual acuity was 20/200 or worse in all eyes, with 88% of eyes having preoperative vision of counting fingers, hand movements, or light perception. The percentage of eyes with postoperative visual acuity of 20/100 or better was 67% at 6 months (n = 45), 75% at 1 year (n = 28), 69% at 2 years (n = 13), and 100% at 3 years (n = 7). In the 31% of patients in whom preoperative vision in the contralateral eye was 20/50 or better, the postoperative vision in the operative eye improved to 20/50 or better in 47% at the last follow-up (average, 18 months; range, 4-49 months). The overall keratoprosthesis retention rate was 84% at an average follow-up of 17 months (79 person-years of follow-up), with 100% retention in 8 eyes with no history of prior corneal transplantation (14.8 person-years of follow-up). The most common postoperative complications were retroprosthetic membrane formation (22 eyes) and persistent epithelial defects (19 eyes). No cases of infectious endophthalmitis were encountered, and only 1 patient with a history of glaucoma required additional glaucoma surgery during the postoperative period.
  
  
  CONCLUSIONS
  The Boston type I keratoprosthesis is an effective means of managing repeat corneal graft failure and corneal limbal stem cell failure with or without corneal opacification in patients with both unilateral and bilateral visual impairment.
authors.affiliation: Cornea Service, The Jules Stein Eye Institute, David Geffen School of Medicine at UCLA, Los Angeles, California 90095, USA. aldave@jsei.ucla.edu
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Aldave
authors.forename: Khairidzan M
authors.initials: KM
authors.lastname: Kamal
authors.forename: Rosalind C
authors.initials: RC
authors.lastname: Vo
authors.forename: Fei
authors.initials: F
authors.lastname: Yu
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001187:Artificial Organs; D003315:Cornea; D003316:Corneal Diseases / Q000601:surgery*; D016039:Corneal Transplantation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications; D019736:Prostheses and Implants; D012189:Retrospective Studies; D017211:Treatment Failure; D016896:Treatment Outcome; D014792:Visual Acuity / Q000502:physiology