Characteristics and Management of Boston Type 1 Keratoprosthesis Explantation: University of Montreal Hospital Center Experience
To describe the characteristics of patients who had Boston keratoprosthesis (KPro) explantation and the outcomes of their subsequent management.
Retrospective observational study. 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 (n=11) were identified and compared to those with KPro retention (n=99). Visual acuity, expressed as LogMAR, was followed as primary outcome. A value of p<0.05 was considered significant.
The analysis included a total of 345.1 life-years of device implantation. 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), hypotony and painful blind eye (1 each). Compared to patients with KPro retention, those requiring KPro explantation were associated with aniridia (p=0.0038), sterile keratolysis (p<0.001), retroprosthesis membrane (p=0.02) and intraocular inflammation (p=0.04). 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=0.02).
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.