title: Retention of the Boston keratoprosthesis type 1: multicenter study results.
abstract: OBJECTIVE
  To report the retention rate of the Boston keratoprosthesis type 1 and to identify risk factors for keratoprosthesis loss.
  
  
  METHODS
  Cohort study.
  
  
  METHODS
  A total of 300 eyes of 300 patients who underwent implantation of the Boston keratoprosthesis type I device between January 2003 and July 2008 by 19 surgeons at 18 medical centers.
  
  
  METHODS
  Forms reporting preoperative, intraoperative, and postoperative parameters were prospectively collected and subsequently analyzed at a central data collection site.
  
  
  METHODS
  Keratoprosthesis retention.
  
  
  RESULTS
  A total cumulative number of 422 life-years of device implantation are included in this analysis. The average duration of follow-up was 17.1 ± 14.8 months, with a range of 1 week to >6.1 years. Ninety-three percent of the 300 Boston keratoprosthesis implants were retained at their last follow-up, corresponding to a retention time of 396 patient-years or 1.42 years/keratoprosthesis. The probability of retention after 1 year and 2 years was 94% and 89%, respectively. During the study period, 21 (7%) eyes failed to retain the device; the reasons for keratoprosthesis loss include sterile keratolysis (9), fungal infections (8), dense retroprosthetic membranes (3), and bacterial endophthalmitis (1). Multivariate analysis demonstrated 3 independent risk factors for keratoprosthesis loss: autoimmune cause (hazard ratio [HR], 11.94; 95% confidence interval [CI], 3.31-43.11), ocular surface exposure requiring a concomitant tarsorrhaphy (HR, 3.43; 95% CI, 1.05-11.22), and number of prior failed penetrating keratoplasties (HR, 1.64; 95% CI, 1.18-2.28).
  
  
  CONCLUSIONS
  The Boston keratoprosthesis type 1 seems to be a viable option for eyes that are not candidates for penetrating keratoplasty (PK). Ocular surface disease due to an autoimmune cause demonstrated the lowest retention rate.
  
  
  BACKGROUND
  The author(s) have no proprietary or commercial interest in any materials discussed in this article.
authors.affiliation: Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts 02114, USA. Joseph_Ciolino@meei.harvard.edu
authors.forename: Joseph B
authors.initials: JB
authors.lastname: Ciolino
authors.forename: Michael W
authors.initials: MW
authors.lastname: Belin
authors.forename: Amit
authors.initials: A
authors.lastname: Todani
authors.forename: Khalid
authors.initials: K
authors.lastname: Al-Arfaj
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Rudnisky
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001187:Artificial Organs; D002648:Child; D015331:Cohort Studies; D003315:Cornea; D003316:Corneal Diseases / Q000503:physiopathology / Q000601:surgery*; D016039:Corneal Transplantation; D005260:Female; D005500:Follow-Up Studies; D006084:Graft Rejection / Q000209:etiology; D006085:Graft Survival / Q000502:physiology*; D006801:Humans; D007431:Intraoperative Complications; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications; D011446:Prospective Studies; D019919:Prosthesis Implantation; D012307:Risk Factors; D055815:Young Adult