Retroprosthetic Membrane Research Articles

Retroprosthetic Membrane Formation in Boston Keratoprosthesis: A Case-Control-Matched Comparison of Titanium Versus PMMA Backplate.

Retroprosthetic membrane (RPM) formation is the most common complication after Boston type 1 keratoprosthesis (KPro) implantation. It affects visual acuity and can predispose to corneal melt. Two KPro backplate materials are available: titanium and polymethyl methacrylate (PMMA). This study investigates the influence of the KPro backplate material on visually significant RPM formation. A retrospective case-control-matched study involving 40 patients; 20 eyes implanted with a titanium backplate KPro were case-matched with 20 eyes implanted with a PMMA backplate KPro between 2007 and 2015 with 1-year minimum follow-up. The mean follow-up duration was 28.1 ± 8.9 and 53.6 ± 24.3 months in the titanium and PMMA groups, respectively. At 12 months postoperatively, 7 eyes with titanium and 6 eyes with PMMA backplates developed a visually significant RPM. By the end of the study, a total of 11 eyes with titanium and 9 eyes with PMMA KPros developed a visually significant RPM. There was no statistically significant difference between both groups. Three of 11 eyes with titanium KPros that had a visually significant RPM required surgical membranectomy, whereas all eyes with PMMA KPros were successfully treated with the yttrium-aluminum-garnet laser. Recurrence of RPMs was found in 7/11 eyes in the titanium group and 2/9 eyes in the PMMA group with no statistical significance. Titanium backplate KPros do not significantly reduce RPM formation compared with PMMA backplate KPros in a case-control-matched setting. A larger prospective study is warranted to evaluate comparative long-term performance and guide newer designs.

Long-Term Visual Outcomes, Complications, and Retention of the Boston Type I Keratoprosthesis.

To report the long-term outcomes of the Boston type I keratoprosthesis (KPro). Data were collected regarding preoperative characteristics, surgical procedure(s) performed, and postoperative outcomes of patients who underwent KPro implantation from May 1, 2004, to May 1, 2011, and were followed for 5 years after surgery. Seventy-four KPro procedures were performed in 58 eyes (55 patients), with more than 1 KPro implanted in 10 eyes. The mean follow-up duration was 82.8 ± 20.5 months (range 57-145 months), and the most common indication for keratoprosthesis implantation was corneal transplant failure (50%). Preoperative corrected distance visual acuity (CDVA) was ≥20/200 in 5%; between 1 and 8 years after surgery, the percentage of eyes with CDVA ≥20/200 varied between 57% (4 years) and 82% (8 years). Nineteen (25.7%) KPros implanted were removed (retention failure rate 0.047/eye-year), although a KPro was retained at final follow-up in 55 eyes (94.8%). The most common postoperative complication was retroprosthetic membrane formation in 51.7% of eyes. The incidence of each postoperative complication decreased significantly over the first 10 years after surgery. The KPro provides significant visual improvement in most eyes, with more than 50% regaining and maintaining 20/200 CDVA each year through 8 years after surgery. The incidence of each postoperative complication decreases significantly over the first 10 years after surgery. Although almost one-quarter of implanted keratoprostheses were removed, over 90% of eyes reaching 5 years of follow-up retain a keratoprosthesis at final follow-up.

Intermediate-Term and Long-Term Outcomes With the Boston Type 1 Keratoprosthesis in Aniridia.

To report the intermediate- and long-term visual outcomes and complications with the Boston type 1 keratoprosthesis (KPro) for the management of aniridic keratopathy. A retrospective chart review of 46 eyes of 34 patients (20 females and 14 males) with aniridic keratopathy who underwent Boston type 1 KPro surgery by a single surgeon from 2004 to 2012 with minimum 2-year follow-up was conducted. Preoperative, intraoperative, and postoperative parameters were collected and analyzed. The primary outcome was the change in best-corrected visual acuity. Secondary outcomes included the rate of retroprosthetic membrane formation, glaucoma progression, glaucoma tube revisions, and KPro retention. Mean age of the patients was 43.5 ± 19.8 years with a mean follow-up period of 4.5 ± 1.6 years (range 2-7.4 years). Thirty-four eyes (74%) had previously failed keratoplasty. Thirty-five eyes (76%) previously underwent ocular surface stem cell transplantation, specifically a keratolimbal allograft. Within the first 6 months postoperatively, 74% (34/46) of patients experienced a gain of ≥2 lines of vision. Overall, there was a gain of ≥2 lines of vision in 43.5% (20/46) of patients at last follow-up. The rate of retroprosthetic membrane formation was 61%, the rate of glaucoma onset/progression was 26%, the rate of tube revision was 31%, and the KPro retention rate was 87%. This study confirms that initial visual improvement in aniridic keratopathy cases occurs at a high rate with the Boston type 1 KPro but also found progressive loss of these initial visual improvements.

Visual Outcomes and Complications of Type I Boston Keratoprosthesis in Children: A Retrospective Multicenter Study and Literature Review

To report outcomes and complications of Boston type 1 keratoprosthesis (KPro) implantation in children. Retrospective, multicenter case series. All children 16 years of age or younger who underwent KPro surgery at 3 ophthalmology centers in Canada between January 2010 and November2014. Records of patients having undergone KPro implantation were reviewed. Data on preoperative characteristics, surgical procedure(s) performed, and postoperative outcomes were collected and analyzed. Intraoperative and postoperative complications, device retention, and best-corrected visual acuity (BCVA). The KPro was implanted in 11 eyes of 11 patients 0.9 to 15.5 years of age, with 6 being primary corneal procedures. Best-corrected visual acuity recorded before surgery ranged from 20/600 to light perception (LP), and vision in 2 eyes was fix and follow. All patients had been diagnosed with glaucoma and 6 eyes had glaucoma drainage devices (GDDs) inserted before KPro implantation. At last follow-up (mean, 41.8 months; range, 6.5-85.0 months), 2 eyes retained BCVA of 20/400 or better, whereas 5 eyes lost LP. Postoperative complications included retroprosthetic membrane (9 eyes), corneal melt (5 eyes), infectious keratitis (3 eyes), endophthalmitis (3 eyes), GDD erosion (2 eyes), and retinal detachment (5 eyes). The initial KPro was retained in 4 eyes (36.4%). Boston type 1 keratoprosthesis implantation in children is associated with a substantially higher rate of complications, higher chance of device failure, and worse visual outcomes than observed in adults. In view of these results, the authors do not recommend the use of the KPro in the pediatric population.

Mid- and Longterm Experiences with the Boston-Keratoprosthesis. The Cologne and Salzburg Perspective

Background Eyes with severe corneal opacifications and insufficient prognosis for high-risk corneal transplantation can be considered for the implantation of a Boston-keratoprosthesis. Since 2013, this technique of "artificial" corneal replacement is provided to high-risk eyes at the Department of Ophthalmology, University of Cologne and for 9 years at the University of Salzburg. In the meantime, a type I Boston keratoprosthesis (BI-KPro) has been implanted in 24 eyes in Cologne and in 28 eyes in Salzburg. Methods In this article, results and complications according to BI-KPro are discussed, both from the literature in PubMed, as well as from our own experiences. Results Twenty-four eyes of 22 patients had been provided with a BI-KPro since September 2013, of which only one keratoprosthesis could not be obtained thus far, and an increase in visual acuity could be achieved in 23 eyes (96%). On average, 1.5 revisions per eye were required during the postoperative course. Since 2007, a BI-KPro has been implanted in 28 eyes in Salzburg. In 62% (16 of 26 eyes), visual acuity increased postoperatively, with a complication rate of 81% in a longer follow-up period. In both cohorts, the spectrum of complications ranged from retroprosthetic membrane formation, to secondary glaucoma, to infectious keratitis with or without graft melting, to vitritis, to endophthalmitis. Conclusion The range of possible complications according to BI-KPro is broad, but the BI-KPro represents currently the most widely used form of artificial corneal replacement in high-risk eyes and leads to visual improvement in most patients.

Impact of Total Pars Plana Vitrectomy on Postoperative Complications in Aphakic, Snap-On, Type 1 Boston Keratoprosthesis

To determine the impact of total pars plana vitrectomies (PPVs) with peripheral shaving of the vitreous base on the rates of postoperative complications in patients with aphakic, snap-on type I Boston keratoprostheses (KPros). Retrospective, consecutive case series. A total of 48 eyes in 46 patients with implantation of aphakic, snap-on type 1 Boston KPros performed at a tertiary care facility between January 1, 2007, and December 31, 2013, were included. The cumulative incidences of postoperative complications were compared between patients who underwent total PPVs with shaving of the vitreous base (n= 22) and those who had partial PPVs or anterior vitrectomies (AVs) at the time of KPro implantation (n= 26). Rates of complications between patients who underwent total PPVs and partial PPVs or AVs. The rate of total postoperative complications was lower in the total PPV group (P= 0.018, log-rank test). In particular, eyes that underwent total PPVs had lower rates of retroprosthetic membranes (RPMs) requiring intervention (P= 0.049) and less vision loss due to glaucoma progression (P= 0.046). There was also a trend for fewer corneal melts (P= 0.060) and less sight-threatening complications (P= 0.051) in the total vitrectomy group. There was no difference in the rates of KPro extrusion (P= 0.41), endophthalmitis or vitritis (P= 0.15), retinal detachments (P= 0.76), cystoid macular edema (P= 0.83), or timing of complications between the 2 groups. The mean preoperative and postoperative visual acuities were similar between the 2 groups (P= 0.97). The mean follow-up was 49±22 months. Eyes that underwent total PPVs during implantation of aphakic, snap-on, type I Boston KPros had less postoperative complications than eyes with partial PPVs or AVs during the average 4 years of follow-up.

Corneal Melt after Boston Keratoprosthesis: Clinical Presentation, Management, Outcomes and Risk Factor Analysis

ABSTRACTPurpose: To determine the presentation, risk factors, and outcomes of keratolysis after Boston type I keratoprosthesis (B-KPro).Methods: Retrospective chart review.Results: A total of 16 (14%) of the 110 eyes (96 patients) which underwent B-KPro implantation developed keratolysis at an average 20 ± 11 months. Retroprosthetic membrane (RPM), infectious keratitis, and corneal dellen were identified in 31%, 25%, and 13% of corneal melts, respectively. Five eyes had keratolysis without a readily identifiable cause. RPM (odds-ratio, OR = 4.4, p = 0.02) and infectious keratitis (OR = 17.6, p<0.0005) were confirmed as significant risk factors. Retinal detachment (p = 0.001) and choroidal detachment (p = 0.003) were more common in eyes with keratolysis. Management included B-KPro removal or exchange (n = 7), amniotic membrane transplantation (n = 1), tectonic corneal transplantation (n = 2), medical treatment (n = 4), and observation (n = 2).Conclusions: The risk of keratolysis following B-Kpro increases with the development of RPM and infectious keratitis. Patients with keratolysis had higher complication rates and should receive rigorous monitoring.

Russian Keratoprosthesis in Stevens-Johnson Syndrome.

To evaluate the efficacy and safety of Moscow Eye Microsurgery Complex in Russia (MICOF) keratoprosthesis (KPro) implantation in patients with Stevens-Johnson syndrome (SJS). This was a retrospective case series. Fourteen eyes of 13 patients with SJS underwent KPro implantation at the Chinese People's Liberation Army General Hospital between April 1, 2000, and December 24, 2014. The visual outcome, KPro retention rate, and incidence of postoperative complications and their management were recorded and investigated. The mean age and follow-up duration were 61.5 ± 17.3 years (range: 27-87 yrs) and 62 ± 39.1 months (range: 13-144 mo). Thirteen eyes (92.9%) achieved a best-corrected visual acuity of 20/200 or better, and 8 eyes (57.1%) achieved a best-corrected visual acuity of 20/40 or better after surgery. However, 71.4% (10/14) experienced visual decline because of different postoperative complications. Common complications included corneal melting, glaucoma, vitritis, superficial tissue overgrowth, and retroprosthetic membrane, and the incidence of these complications was 71.4%, 28.6%, 35.7%, 14.3%, and 28.6%, respectively. After repair and autoauricular cartilage reinforcement, all cases had stable anatomical retention at the last visit. The MICOF KPro improved vision of patients with SJS, but lifelong surveillance is necessitated because of a high rate of postoperative complications. Corneal melting was the main reason for KPro failure. Infectious endophthalmitis and glaucoma were the main risk factors for visual loss.

Outcomes After Auro Keratoprosthesis Implantation: A Low-Cost Design Based on the Boston Keratoprosthesis.

To evaluate outcomes after Auro keratoprosthesis (kpro) implantation. Retrospective observational case series. The records of all patients who were implanted with Auro kpro from December 2012 to August 2015 at a single institute were retrospectively analyzed to evaluate preoperative characteristics, postoperative outcomes, and complications. Fifteen cases were included in the study. Failed graft was the most common indication for the surgery (n = 14; 93.3%). The mean BCVA (Log MAR) improved from 2.20 ± 0.43 in the preoperative period to 1.46 ± 1.12 (P = 0.0247) at the mean final follow-up of 13.5 months. The best corrected visual acuity (BCVA) improved to 20/200 or better in 9 patients (60%) at the final follow-up. Postoperative complications included retroprosthetic membrane formation (n = 7; 46.7 %), graft infection (n = 4; 26.7%), sterile corneal melt (n = 3; 20%), and spontaneous optic extrusion (n = 1; 6.7%). Eleven patients retained prosthesis at the final follow-up (retention rate = 73.3%). Auro kpro seems to be effective in treating end-stage corneal diseases. The outcomes are comparable to Boston kpro in terms of visual acuity, postoperative complications, and retention rates.

Safety of Concurrent Boston Type I Keratoprosthesis and Glaucoma Drainage Device Implantation

To evaluate the safety of concurrent Boston type I keratoprosthesis (KPro) and glaucoma drainage device (GDD) implantation. Retrospective comparative study of a consecutive cohort of patients. Patients who underwent KPro implantation by a single surgeon (A.J.A.) with or without 1 concurrent Ahmed GDD (New World Medical, Inc., Rancho Cucamonga, CA) implantation between January 1, 2005, and January 31, 2015, were included. Patients with fewer than 3 months of follow-up or a history of previous KPro implantation were excluded. Preoperative, operative, and postoperative data were collected for each procedure. All comparisons were made between KPro procedures performed with or without concurrent GDD implantation. The Fisher exact test (2-tailed) was used to compare proportions, Student t test and Wilcoxon rank-sum test were used to compare means, and the log-rank test was used to compare time-to-outcome events. The primary outcome was frequency of the composite variable, that is, any serious vision-threatening postoperative complication, which included sterile vitreitis, endophthalmitis, hypotony maculopathy, suprachoroidal hemorrhage, retinal detachment, stromal necrosis, and infectious keratitis. Secondary outcomes included intraocular pressure control, worsening of visual acuity, cystoid macular edema, retroprosthetic membrane formation, persistent epithelial defect formation, GDD exposure, and KPro removal. One hundred thirty-seven KPro procedures were performed in 129 patients: 91 (66.4%) KPro alone and 46 (33.6%) KPro plus GDD. There were no statistically significant differences between the 2 groups in terms of the incidence of vision-threatening postoperative complications. None of the 46 GDDs placed at the same time as the KPro became exposed during an average follow-up of 44 months. Compared with KPro alone, GDD placement combined with KPro was not associated with increased postoperative complications.

Boston Type 1 Keratoprosthesis: Visual Outcomes, Device Retention, and Complications.

To determine the visual outcomes, device retention, and complications after Boston type 1 keratoprosthesis (KPro-1) device implantation. Comprehensive review of every case of KPro-1 implantation at a tertiary eye care center. The initial KPro-1 procedure, performed in 75 eyes without a previous keratoprosthesis, was included in the analysis. During the first 6 postoperative months, improvement occurred in the mean preoperative best-corrected visual acuity of 20/1265 to a mean best-obtained postoperative visual acuity of 20/97 (P < 0.001). After a mean follow-up period of 41.4 months (range, 0.8-82.8 months), the final mean best-corrected visual acuity was 20/428. Improved vision was recorded in 43 eyes (57.3%), ambulatory vision (≥20/400) in 47 eyes (62.7%), intermediate functional vision (≥20/80) in 23 eyes (30.7%), and full functional vision (≥20/40) in 11 eyes (14.7%). The initial device was retained in 64 eyes (85.3%), with a Kaplan-Meier retention probability of 96% at 6 months and 82% at 5 years. One or more sight-threatening complications occurred in 51 eyes (68%). These included device extrusion in 11 eyes (14.7%), ulcerative keratitis in 12 eyes (16%), endophthalmitis in 7 eyes (9.3%), sterile vitritis in 3 eyes (4%), retroprosthetic membranes in 25 eyes (33.3%), maculopathy in 26 eyes (34.7%), retinal detachment in 9 eyes (12%), and progressive optic neuropathy in 7 eyes (9.3%). Boston KPro-1 implantation is associated with satisfactory visual outcomes and excellent device retention in a majority of cases. However, serious postoperative complications are common and may compromise the final visual result.

Long-term Visual Outcomes and Complications of Boston Keratoprosthesis Type II Implantation

To report the long-term visual outcomes and complications after Boston keratoprosthesis type II implantation in the largest single-center case series with the longest average follow-up. Retrospective review of consecutive clinical case series. Between January 1992 and April 2015 at the Massachusetts Eye and Ear Infirmary, 48 eyes of 44 patients had keratoprosthesis type II implanted by 2 surgeons (C.H.D. and J.C.). For each eye, data were collected and analyzed on the preoperative characteristics, intraoperative procedures, and postoperative course. Visual acuity outcomes, postoperative complications, and device retention. The most common indications for surgery were Stevens-Johnson syndrome in 41.7% (20 of 48 eyes) and mucous membrane pemphigoid in 41.7% (20 of 48 eyes). Mean follow-up duration was 70.2 months (standard deviation, 61.8 months; median, 52 months; range, 6 months to 19.8 years). Almost all patients (95.8%, 46 of 48 eyes) had a preoperative visual acuity of 20/200 or worse. Postoperative visual acuity improved to 20/200 or better in 37.5% (18 of 48 eyes) and to 20/100 or better in 33.3% (16 of 48 eyes) at the last follow-up visit. The most common postoperative complication was retroprosthetic membrane formation in over half (60.4%, 29 of 48 eyes). The most pressing postoperative complication was glaucoma onset or progression in about a third. Preexisting glaucoma was present in 72.9% (35 of 48 eyes). Glaucoma progressed in 27.1% (13 of 48 eyes) and was newly diagnosed in 8.3% (4 of 48 eyes) after surgery. Other postoperative complications were tarsorrhaphy revision in 52.1% (25 of 48 eyes), retinal detachment in 18.8% (9 of 48 eyes), infectious endophthalmitis in 6.3% (3 of 48 eyes), and choroidal detachment or hemorrhage in 8.3% (4 of 48 eyes). Half of eyes retained their initial keratoprosthesis at the last follow-up (50.0%, 24 of 48 eyes). The Boston keratoprosthesis type II is a viable option to salvage vision in patients with poor prognosis for other corneal procedures. Retroprosthetic membranes, keratoprosthesis retention, and glaucoma are major challenges in the postoperative period; however, the keratoprosthesis can still provide improved vision in a select group of patients.

Retroprosthetic Membrane Formation After Boston Keratoprosthesis: Is It Truly a Benign Complication?

Advances in Boston type 1 keratoprosthesis (K-Pro) technology and postoperative management have led to a decrease in postoperative complications and expanded indications in recent years. However, several challenges still remain, including the post-implantation development of fibrous tissue behind the device known as a retroprosthetic membrane (RPM). Herein, we review the epidemiology, pathophysiology, detection, treatment, prevention, and sequelae of RPM formation after keratoprosthesis implantation. Among postulated risk factors, device indication has been found to be a significant predictor of RPM formation. However, the etiology is likely multifactorial and probably involves both pathologic wound healing triggered by the device and host-specific factors. Anterior segment optical coherence tomography is emerging as a useful tool in the detection and monitoring of RPM formation. Once diagnosed, most RPMs affecting vision are responsive to therapy. However, attempts to reduce the burden of RPM formation including the utility of intracameral corticosteroid prophylaxis at the time of surgery have shown limited effect. Beyond visual impairment, evidence suggests that membrane extension behind the back-plate and into local intraocular structures may contribute to significant morbidity. Indeed, recent reports of RPM-related sequelae include sterile keratolysis and K-Pro extrusion, angle closure and glaucoma development, and, in some cases, tractional retinal detachments. RPM formation after K-Pro implantation compromises the stability of the device and long-term patient outcomes. Accordingly, further investigations are needed to understand RPM etiology in order to inform the development of more effective strategies for prophylaxis and treatment.

Boston keratoprosthesis type I in the elderly

Background/aimsTo determine the outcomes of Boston type I keratoprosthesis implanted in elderly patients.MethodsA retrospective case series was performed on patients at least 75 years old who received the Boston type...

Boston Type 1 Keratoprosthesis for Gelatinous Drop-Like Corneal Dystrophy.

To report the outcomes of Boston type 1 keratoprosthesis in the management of advanced gelatinous drop-like corneal dystrophy (GDLD). A retrospective, noncomparative, interventional case series was conducted at Ramathibodi Hospital, Bangkok, Thailand. Four eyes of three siblings with molecularly and histologically confirmed GDLD from a Thai family underwent an uneventful Boston type 1 keratoprosthesis implantation for visual rehabilitation. Clinical data were obtained from a review of the medical records. Visual acuity, device retention, and postoperative complications were the main outcome measures. The follow-up ranged from 8 to 96 months. One eye received keratoprosthesis surgery as a primary penetrating procedure. The other three eyes had the surgery as a secondary procedure after graft failure. Best-corrected visual acuity was favorably improved from counting fingers to 20/25 in two eyes, from hand movement to 20/20 in one eye, and from hand movement to counting fingers at 2 feet in one eye caused by severe amblyopia. The improved vision was maintained for 8 months to 6.2 years after surgery. Postoperative complications included disease recurrence in the donor graft (N = 3), manageable retroprosthetic membrane (N = 3), intraocular pressure elevation responded to antiglaucoma drugs (N = 2), and Pseudomonas keratitis with severe corneal melting requiring device removal (N = 1). All of our patients failed to have a comfortably well-fitting contact lens after surgery. Boston type 1 keratoprosthesis could be considered as a reasonable option in the management of advanced GDLD. However, patients remain at risk for sight-threatening postoperative complications as long as the keratoprosthesis is retained. The use of Boston keratoprosthesis implantation needed to be individualized on a case-by-case basis.

Boston Keratoprosthesis Outcomes in Severe Ocular Chemical Burns in Southern China: A Retrospective Study.

The objective of this study was to report clinical outcomes (functional and anatomic) of Boston keratoprosthesis (KPro) after severe chemical burns in Southern China. Nineteen patients (19 eyes) that sustained severe chemical injuries in Southern China were enrolled in this retrospective study in our hospital between May 2009 and June 2015. KPro implantation in these patients was performed by a single experienced surgeon (Jiaqi Chen). The parameters evaluated in this study included diagnosis, comorbidity, preoperative and postoperative visual acuity (VA), complications, KPro retention, histological and immunohistochemical results of retroprosthetic membrane (RPM) and mucous membrane over the optic cylinder. The mean age of the patients was 42.7±11.3years (range 29-62years). All patients were male. Of the 19 included eyes, nine had acid burns, and 10 had alkali burns. Ten patients had previously undergone failed penetrating keratoplasty. The mean follow-up time was 41.3±5.5months (range 36-56months). Preoperatively, the VA of the patients ranged from hand movement to light perception. Postoperatively, 17 patients (89.4%) achieved at least 20/200 once, and 7 patients (36.8%) achieved at least 20/200 and maintained this acuity until the last follow-up. The initial KPro was retained in 14 (73.6%) eyes and successfully replaced in one eye. Postoperative complications included RPM in 10 eyes, glaucoma in 6 eyes, retinal detachment in 2 eyes, corneal melting in 5 eyes, ischemic optic neuropathy in 1 eye, and overgrowth of the mucous membrane over the optical cylinder in 2 eyes. The histological and immunohistochemical results of the RPM showed granulomatous disorders and mucous membrane over the optic cylinder of conjunctival origin. KPro surgery can restore useful vision in patients suffering from severe chemical burns. However, postoperative VA declined with the development of complications, and ocular surface disorders caused by the chemical burns were associated with a greater incidence of KPro retention failure. The retention rate was comparable in patients using ipsilateral autologous corneal tissue with allograft corneal tissue. Science and Technology Foundation of Guangdong Province of China, Grant Number 2014A020212714.

Type 1 Boston keratoprosthesis: outcomes at two Canadian centres

ObjectivesTo report the outcomes of patients who underwent Boston type 1 keratoprosthesis (Kpro) surgery at the University Health Network (Toronto, Ont.) and the University of Ottawa Eye Institute (Ottawa, Ont.) between June 2008 and July 2013. DesignRetrospective case series. ParticipantsForty-four eyes of 43 patients who underwent Kpro surgery. MethodsA retrospective review was conducted of all Kpro procedures performed by 4 attending cornea surgeons. The preoperative characteristics and postoperative course of each patient were analyzed. ResultsIn 31 eyes (70%), the primary indication for a Kpro was failed corneal transplantation. The remaining 13 eyes (30%) had Kpro as a primary procedure. In all eyes, preoperative visual acuity (VA) was 20/150 or worse, with 39 eyes (89%) having a VA of counting fingers, hand movement, or light perception. Mean follow-up time was 21 ± 12 months (range 12–57 months). The retention rate at the last follow-up was 95%. Best-achieved median VA was 20/100 (range 20/20 to no light perception [NLP]), with 37% of patients achieving a VA of >20/40 at some point during their postoperative course. At the last follow-up, median VA was 20/400 (range 20/30 to NLP). The 2 most common complications included retroprosthetic membrane formation (23 eyes, 52%) and elevated intraocular pressure (10 eyes, 23%). There were 5 cases (11%) of stromal melt and 1 case (2%) of infective keratitis. ConclusionsThis study demonstrates that Kpro improves VA in a majority of cases, and is a viable option in situations in which there is a poor prognosis for traditional penetrating keratoplasty.

VITREORETINAL COMPLICATIONS IN EYES WITH BOSTON KERATOPROSTHESIS TYPE I.

To describe the spectrum of vitreoretinal complications in eyes with Boston keratoprosthesis type I and evaluate the treatment outcomes. This was a retrospective interventional case series of 23 of 45 eyes that underwent Boston keratoprosthesis from April 2003 to December 2013 and developed vitreoretinal complications. Types of vitreoretinal complications, surgical techniques, and anatomical and visual outcomes were analyzed. Vitreoretinal complications in eyes with Boston keratoprosthesis included retroprosthetic membranes (n = 11), retinal detachment (n = 6), endophthalmitis (n = 4), epiretinal membrane (n = 4), vitreous hemorrhage (n = 2), and choroidal detachment (n = 1). Twenty of 23 eyes (87%) underwent surgical intervention. Retinal reattachment was achieved in 5 eyes (83%) with significant visual improvement in 3 (50%). Mean preoperative visual acuity improved from 1.84 ± 0.89 logMAR to 1.5 ± 0.87 logMAR (P = 0.01) at the last follow-up. Mean 1.4 surgical procedures were performed per eye. Mean follow-up was 28 months (median: 28 months, range: 5-57 months). Retroprosthetic membrane and retinal detachment are most common vitreoretinal complications in eyes with Boston keratoprosthesis. Vitreoretinal complications can be managed by appropriate intervention in such eyes with encouraging anatomical and functional results.

High MMP-9 Expression May Contribute to Retroprosthetic Membrane Formation after KPro Implantation in Rabbit Corneal Alkali Burn Model.

Purpose. To evaluate aqueous humor MMP-9 levels in alkali-burned rabbit cornea following KPr implantation and their roles in RPMs formation. Methods. Left eyes of 36 rabbits received a deep corneal alkali wound. 12 corneas were implanted with KPro and the other 24 control corneas were either penetrating keratoplasty or left without keratoplasty. Aqueous humor MMP-9 and TIMP-1 levels were determined and RPMs were obtained for histopathological and ultrastructural examination. Results. Alkali exposure induced significant increase in aqueous humor MMP-9 level and the data were further enhanced by KPro implantation. By contrast, TMIP-1 levels in aqueous humor showed a decreased trend following corneal alkali burn and KPro surgery. RPMs were developed in 5 out of 10 cases of KPro successfully implanted eyes. Histopathology showed the presence of a large number of fibroblasts and collagen fibers arranged irregularly with inflammatory cells infiltration, and an ingrowth of new blood vessels in this retrokeratoprosthesis fibrous tissue. Immunohistochemical analysis showed positive stain of RPMs for both MMP-9 and TIMP-1. Aqueous humor MMP-9 levels were significantly higher in RPM group postoperatively, while TIMP-1 levels were comparatively lower than that of No-RPM group. Conclusions. Our study evidenced the potential pathophysiological role of MMP-9 expression in RPM formation following KPro implantation.

Long-term visual acuity, retention and complications observed with the type-I and type-II Boston keratoprostheses in an Irish population

AimTo evaluate the outcomes of the type-I and type-II Boston keratoprostheses in a single Irish centre.MethodsA retrospective chart review of keratoprosthesis implantations carried out in our institution from November 2002...