Boston Type 1 Keratoprosthesis for Iridocorneal Endothelial Syndromes

Systematic Review and Meta-Analysis of the Medium- and Long-Term Outcomes of the Boston Type 1 Keratoprosthesis

PURPOSE

The Boston type 1 keratoprosthesis (KPro), used in patients with high risk of corneal graft failure, is increasingly being used. However, the medium- to long-term outcomes are currently unclear. We analyzed the medium- (2-5 years) and long-term (>5 years) efficacy and safety of the Boston type 1 KPro in terms of visual outcomes, device retention, and postoperative complications.

METHODS

We last searched electronic databases (Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid MEDLINE Epub Ahead of Print, EMBASE, and CENTRAL) on March 31, 2018. Visual outcomes and device retention at 2 and 5 years, alongside postoperative complications, were primary outcome measures.

RESULTS

We identified 407 articles. Thirty studies were included in this systematic review and meta-analysis. The combined proportion of eyes with ≥6/60 vision was 62% at 2 years and 51% at 5 years. The combined retention rate was 88% at 2 years and 74% at 5 years. Retroprosthetic membrane (36.6%) and glaucoma (39.3%) were found to be the most common long-term complications. Very few studies showed visual outcomes or retention rates at 5 years, with results sparse and collectively not meaningful because of small patient numbers and ambiguous reporting of follow-up times.

CONCLUSIONS

The 2-year results indicate that there is a place for the Boston type 1 KPro in the management of corneal blindness. However, there is scarce evidence regarding its medium- and long-term efficacy and safety. The high rate of reported complications necessitates strict patient selection and stringent follow-up.

Iridocorneal endothelial syndrome: clinical perspectives

This article aims to review the clinical management strategies available for the rare iridocorneal endothelial syndrome. The different clinical variations as well as the imaging techniques available to aid diagnosis are discussed. We then present the evidence available to help the reader to understand how the condition can be managed medically and also the important surgical aspects of treatment. This involves raised intraocular pressure management in addition to the visual management options of partial or full thickness keratoplasty. We hope that this review provides an exhaustive but also succinct review of the literature available on what is a rare and difficult condition to treat.

Microbial Keratitis and Endophthalmitis After the Boston Type 1 Keratoprosthesis

PURPOSE

To determine the incidence, ocular surface disease associations, microbiological profile, and clinical course of postoperative infections after implantation of the Boston type 1 keratoprosthesis (KPro-1).

METHODS

A retrospective chart review was conducted of all cases of the KPro-1 performed at a tertiary eye care center between January 1, 2008, and December 31, 2014.

RESULTS

Seventy-five KPro-1 procedures were included in the analysis. Postoperative infections occurred in 13 eyes (17.3%) with an incidence of 0.064 cases per eye-year. The Kaplan-Meier probability of an infection-free graft was 0.96, 0.90, 0.88, 0.87, and 0.86 at years 1 through 5, respectively. The rate of infections was greater in eyes with ocular surface disease (26.3% vs. 8.1%, P = 0.06), especially in those with a history of chemical or thermal injury or herpes zoster keratopathy (P = 0.001). There were 8 cases (10.7%) of microbial keratitis due to either fungi (5 cases) or bacteria (3 cases). There were 7 cases (9.3%) of endophthalmitis due to bacteria (5 cases) or intraocular extension of fungal keratitis (2 cases). The incidence of microbial keratitis and endophthalmitis was 0.034 and 0.03 cases per eye-year, respectively. Therapeutic management of the infected eyes required graft and device removal in 7 eyes (53.8%). After completion of microbiologic treatment, 7 eyes (53.8%) had lost more than 2 lines of the best-corrected preinfection visual acuity, including 5 eyes with endophthalmitis that had hand motion vision or worse.

CONCLUSIONS

Postoperative infections are a serious issue that compromises device retention and visual outcomes after keratoprosthesis implantation.