Cataract extraction after implantation of a type I Boston keratoprosthesis

PURPOSE: To describe cataract extraction and intraocular lens placement in a patient with an existing Type I Boston keratoprosthesis. METHODS: Case report to describe the surgical technique used to remove a cataract that developed after Boston keratoprosthesis placement. RESULTS: Extracapsular cataract extraction by using an open-sky technique can be used to remove a cataractous lens in the setting of an existing Boston keratoprosthesis. CONCLUSIONS: Although this case shows that it is possible to perform cataract surgery after Boston keratoprosthesis placement, it is prudent to remove the crystalline lens during the initial surgery, even in the absence of a visually significant cataract, because several factors work together to almost guarantee eventual cataract development if the patient is left phakic.     

Boston type I keratoprosthesis: Review

Regardless of significant progress in the field of corneal transplantation to treat corneal opacification, some cases of corneal blindness still present a poor prognosis for conventional penetrating keratoplasty. In patients with repeated graft failure and/or with severe ocular surface disease, the Boston type I keratoprosthesis (type I BKPro) has become a viable option. Modifications in its design and postoperative management have improved the long-term outcomes of visual acuity, retention, and postoperative infection rates. These advances made the type I BKPro be considered a safe alternative for visual rehabilitation in many patients with corneal pathologies. However, postoperative handle of chronic comorbidities, such as glaucoma, is still critical for preserving the visual gains achieved with BKPro.     

Traumatic wound rupture after Boston type 1 keratoprosthesis implantation

ObjectiveTo describe the incidence, characteristics, causes, treatment, and outcomes of traumatic wound rupture in patients with Boston type 1 keratoprosthesis (KPro).DesignRetrospective case series.ParticipantsWe studied 136 eyes of 122 patients who underwent KPro implantation at a single institute between November 2004 and May 2011.MethodsA chart review was performed to determine the incidence, characteristics, causes, treatments, and outcomes of traumatic wound rupture.ResultsThe 4 eyes of 4 patients that sustained traumatic wound rupture resulted in an incidence of traumatic wound rupture of 2.9% (4/136). This complication occurred, on average, at 4.2 months (range, 1-9 months) after the KPro was implanted. All ruptures occurred at the graft-host junction. The 2 eyes that had complete keratoprosthesis extrusion experienced decreased vision postrupture, from hand motions to no light perception, and 20/300 to count-fingers vision, respectively. One eye that had 4 clock hours of superior wound rupture recovered vision postrupture from light perception to 20/40. One eye that had 2 clock hours of superior wound rupture maintained a stable vision of 20/125 after repair.ConclusionsThe incidence of traumatic wound rupture after keratoprosthesis is comparable to that after penetrating keratoplasty. Patients should be aware that traumatic rupture is a lifelong concern and should use protective measures to prevent this complication from occurring.     

波士顿Ⅰ型人工角膜临床研究进展

波士顿I型人工角膜是目前最被眼科医生接受的一款人工角膜。我们将首先对目前国际上已发表的关于波士顿I型人工角膜的适应证、植入例数、术后随访期内最佳矫正视力和解剖保留率与并发症的发生率等作归纳,然后逐一介绍波士顿I型人工角膜影响术后视力的几个主要术后并发症,包括后增殖膜、青光眼、术后感染的最新研究进展及处理方法。     

Outcomes of Boston keratoprosthesis type 1 reimplantation: multicentre study results

Objective

To investigate the visual and anatomical outcomes of Boston keratoprosthesis (Kpro) type 1 reimplantation.

Frozen versus fresh corneal graft carriers in Boston keratoprosthesis surgery: 10-year outcomes

ObjectiveTo compare 10-year clinical outcomes of frozen versus fresh corneal graft carriers for the Boston Keratoprosthesis type 1 (KPro).DesignProspective, non-masked randomized controlled trial.ParticipantsNineteen eyes of 19 patients having undergone Boston KPro type 1 implantation using a fresh or frozen graft carrier.MethodsAll patients that underwent Boston KPro type 1 implantation by a single experienced surgeon using an allograft carrier between October 2008 and March 2010 at the Centre Hospitalier de l'Université de Montréal were considered. Patients were excluded if they had a history of prior KPro implantation in the same eye. A subset of the patient cohort enrolled in the initial study protocol of 24 months continued follow-up to 120 months. Participants were randomized to receive either a fresh or frozen corneal graft carrier depending on tissue availability from the eye bank on the day of KPro implantation.ResultsNineteen eyes of 19 patients were included, with 11 in the fresh group and 8 in the frozen group. At 10 years, in the fresh and frozen groups respectively, device retention was 91% and 75%; mean best corrected visual acuity increased from counting fingers preoperatively to 20/300 and 20/125; and incidence of complications per patient was 2.36 and 2.37. There were no statistically significant differences between groups for any of these outcome measures (p > 0.05 for all analyses).ConclusionsFresh and frozen corneal graft carriers offer similar clinical outcomes for KPro implantation in terms of device retention, change in visual acuity, and rate of complications at 10 years.     

Anatomical survival and visual prognosis of Boston type I keratoprosthesis in challenging cases

Purpose

To describe the outcome of patients with Boston type 1 keratoprosthesis, with regard to anatomical and visual success.

Methods

Retrospective case series of patients who underwent Boston type I keratoprosthesis surgery at the Centro de Oftalmología Barraquer in Barcelona and at the University Eye Clinic in Salzburg between May 2006 and December 2011. Sixty-seven eyes were included. Anatomical success, visual acuity, and complication rate were evaluated and correlated with the initial diagnosis.

Results

The mean age of patients was 54 years; 62 % were male and 38 % were female. Eleven patients underwent Type I Boston Kpro implantation as a primary procedure, while the other 52 patients had previous graft failure. The most frequent diagnoses were autoimmune diseases (16 eyes), severe chemical or thermal burn (12 eyes), leukoma post-infectious keratitis (seven eyes) and bullous keratopathy (six eyes). The mean follow-up time was 26 months. Retention of the prosthesis was achieved in 95 % at 1 year and 78 % at 4.5 years. Two eyes suffered extrusion of the KPro, six underwent successful exchange of the prosthesis either due to infection, necrosis or extrusion, three KPro’s had to be explantated, and two eyes ended up in enucleation due to panophthalmitis. The outcome of the autoimmune cases was similar to the group with “other diagnoses” and better than those with chemical/thermal burn. The most frequent complication was development of a retroprosthetic membrane in 21 eyes (34 %). Visual acuity (LogMAR) in the chemical/thermal burn group was 2.30 preoperatively, 0.69 at 1 year, 0.52 at 2 years and 0.39 at 3 years; in the autoimmune group visual acuity was 2.3 preoperatively, 0.65 at 1 year, 0.15 at 2 years, and 1.5 at 3 years.

Conclusions

Boston type 1 keratoprosthesis is a viable option for patients with repeated graft failure, even for those with challenging diagnoses such as ocular burns and autoimmune syndromes.     

Boston type 1 keratoprosthesis outcomes in ocular burns

Purpose: To report the outcomes of Boston type I keratoprosthesis (BKPro) in the management of ocular burn injuries. Methods: This was a prospective study including all cases of BKPro implantation for ocular burns at the External Diseases and Cornea Service of the Federal University of São Paulo, between February 2008 and February 2010. Ten patients (10 eyes) were enrolled. Procedures performed to manage ocular injury were identified, and data were collected regarding patients’ ocular history, surgical procedure(s) performed, and postoperative outcomes, including visual acuity, retention, complications and required surgical procedures. Results: A total of 11 Type 1 BKPro were implanted in 10 eyes of 10 patients. The mean follow‐up period was 25.7 ± 10.8 months. Preoperative best‐corrected visual acuity (BCVA) ranged from count fingers to light perception. Postoperative BCVA was better than 20/200 in 90% of the patients and better than 20/60 in 60% of the patients. The overall BKPro retention rate was 90%. The most common complications were retroprosthetic membrane formation (50%) and persistent corneal epithelial defect evolving to corneal melting (40%). Patients who underwent ocular surface procedures such as limbal transplantation prior to BKPRo implantation had a lower incidence of corneal melting/thinning (p = 0.07), although this was not statistically significant. Conclusion: The anatomical and functional results identified in this study support the use of BKPro in managing bilateral limbal stem cell deficiency secondary to ocular burns.     

The treatment of end-stage corneal disease: penetrating keratoplasty compared with Boston type 1 keratoprosthesis

Graefe's Archive for Clinical and Experimental Ophthalmology - Penetrating keratoplasty (PKP) yields excellent results for restoring vision in end-stage corneal diseases. However, its success...     

Cost effectiveness of the type II Boston keratoprosthesis

Purpose

Despite demonstrated cost effectiveness, not all corneal disorders are amenable to type I Boston keratoprosthesis (KPro) implantation. This includes patients with autoimmune diseases, such as Stevens–Johnson syndrome/toxic epidermal necrolysis. Type II KPro is implanted through the eyelids in severe dry eye and cicatricial diseases, and its cost effectiveness was sought.

Patients and methods

In a retrospective chart review, 29 patients who underwent type II KPro surgery at the Massachusetts Eye and Ear Infirmary between the years 2000 and 2009 were identified. A total of 11 patients had 5-year follow-up data. Average cost effectiveness was determined by cost-utility analysis, comparing type II KPro surgery with no further intervention.

Results

Using the current parameters, the cost utility of KPro from third-party insurer (Medicare) perspective was 63 196 $/quality-adjusted life year.

Conclusion

Efforts to refer those less likely to benefit from traditional corneal transplantation or type I KPro, for type II KPro surgery, may decrease both patient and societal costs.