title: Characteristics and management of patients with Boston type 1 keratoprosthesis explantation--the University of Montreal Hospital Center experience.
abstract: OBJECTIVE
  To describe the characteristics of patients who had Boston keratoprosthesis (KPro) explantation and the outcomes of their subsequent management.
  
  
  METHODS
  Retrospective observational study.
  
  
  METHODS
  Cases that underwent Boston type 1 KPro at University of Montreal Hospital Center between October 2008 and May 2012 were reviewed. Patients with KPro explantation were identified and compared to those with KPro retention. Visual acuity, expressed as logMAR, was followed as primary outcome.
  
  
  RESULTS
  A total of 345.1 life-years of device implantation were included in the analysis. Among 110 operated eyes, 11 eyes had KPro explantation, corresponding to a failure rate of 0.03/life-year. KPro was explanted at 19.7 ± 10.5 (4-40) months post KPro. Indications included sterile keratolysis (n = 7), infection (n = 2), and hypotony and painful blind eye (1 each). Compared to patients with KPro retention, those requiring KPro explantation were associated with aniridia (P = .0038), sterile keratolysis (P < .001), retroprosthesis membrane (P = .02), and intraocular inflammation (P = .04). KPro exchange (n = 8), penetrating keratoplasty (n = 1), or evisceration (n = 2) were performed as a secondary intervention. Among patients with KPro explantation, 4 (36.4%) recovered better than baseline visual acuity at final visit. Posterior segment complications (n = 5, 62.5%) were the most common cause of permanent vision loss. Final visual prognosis correlates with pre-explantation visual function (r = 0.68, P = .02).
  
  
  CONCLUSIONS
  Boston KPro explantation is a serious complication. Aniridic eyes are at significant risk and have a shortened keratoprosthesis retention time. When managed appropriately, patients can recover significant vision.
authors.affiliation: Department of Ophthalmology, Centre Hospitalier de l'Université de Montréal (CHUM), Hôpital Notre-Dame, Montreal, Quebec, Canada. Electronic address: qianqian.wang1@gmail.com.
authors.forename: Qianqian
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Department of Ophthalmology, Centre Hospitalier de l'Université de Montréal (CHUM), Hôpital Notre-Dame, Montreal, Quebec, Canada.
authors.forename: Mona
authors.initials: M
authors.lastname: Harissi-Dagher
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001187:Artificial Organs; D001705:Bioprosthesis; D003315:Cornea / Q000473:pathology*; D020878:Device Removal; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications; D011475:Prosthesis Failure; D019919:Prosthesis Implantation; D012189:Retrospective Studies; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult