Retroprosthetic Membrane Formation Research Articles

The modified polymethyl methacrylate-silicone keratoprosthesis in rabbit model.

To evaluate the safety and effectiveness of a modified polymethyl methacrylate-silicone keratoprosthesis and its operation method in alkali-burned rabbit model. The polymethyl methacrylate-silicone keratoprostheses were implanted into seven alkali-burned rabbit corneas by a special operation method using autologous graft as the keratoprosthesis (Kpro) carrier. The long-term postoperative outcomes were evaluated. During a postoperative study period of 16 months, except for one Kpro extruded at 3 months, all Kpros were in good position and were kept transparent without Kpro extrusion, keratolysis, infection, endophthalmitis, or retinal detachment. The postoperative complications included elevated intraocular pressure in two cases and temporary retroprosthetic membrane formation in two cases. The modified polymethyl methacrylate-silicone Kpro and its operation method is a relatively safe and effective choice for alkali-burned rabbit eyes. Elevated intraocular pressure is the main complication needing to be resolved.

Comparison of long-term results between osteo-odonto-keratoprosthesis and tibial bone keratoprosthesis

PurposeTo compare the anatomical and the functional results between osteo-odonto-keratoprosthesis (OOKP) and keratoprosthesis using tibial bone autograft (Tibial bone KPro). MethodsWe reviewed the charts of 258 patients; 145 had OOKP whereas 113 had Tibial bone KPro implanted. Functional success was defined as best corrected visual acuity ≥0.05 on decimal scale and anatomical success as retention of the keratoprosthesis lamina. Kaplan-Meier survival curves were calculated for anatomical and functional survival as well as to estimate the probability of post-op complications. ResultsThe anatomical survival for both KPro groups was not significantly different and was estimated as 67% for OOKP and 54% for Tibial bone KPro at 10 years after surgery. There was also no difference found after subdividing for primary diagnosis groups such as chemical injury, thermal burn, trachoma and all autoimmune cases combined. Estimated functional survival at 10 years post-surgery was 49% for OOKP and 25% for Tibial bone KPro, which was significantly different. The probability of patients with Tibial bone KPro developing one or more post-operative complications at 10 years after surgery (65%) was significantly higher than those with OOKP (40%). Mucous membrane necrosis and retroprosthetic membrane formation were more common in Tibial bone KPro than OOKP. ConclusionBoth types of autologous biological KPro, OOKP and Tibial bone KPro, had statistically similar rate of keratoprosthesis extrusion. Although functional success rate was significantly higher in OOKP, it may have been influenced by a better visual potential in the patients in this group.

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.

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.

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.

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...

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.

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 Results of the Boston Keratoprosthesis for Unilateral Corneal Disease.

To report the results of unilateral implantation of a Boston keratoprosthesis (BKPro) in patients with good visual acuity in the fellow eye. A retrospective analysis of 37 eyes of 37 patients who underwent an optical BKPro and had a preoperative best-corrected visual acuity (BCVA) of 20/40 or better in the fellow eye at Wills Eye Hospital from September 2005 to November 2013 was performed. Patients were excluded if they had less than 1 year of postoperative follow-up. The mean follow-up after BKPro implantation was 31.7 months (range, 12-78 months; SD, 21). Twenty-eight patients underwent a BKPro for failed penetrating keratoplasty, and 9 patients underwent a primary BKPro. The most common complications were elevated intraocular pressure and retroprosthetic membrane formation in 16 eyes (43%) each. The mean final BCVA (1.0 ± 0.8 logMAR; median, 1.0 logMAR) was statistically better than the mean preoperative BCVA (1.8 ± 0.2 logMAR; median, 1.8 logMAR) (P < 0.001). The probability of postoperative BCVA of 20/200 or better was 54.1% with an average 45.1 ± 4.7 (confidence interval: 35.9-54.3) months of follow-up. The probability of postoperative BCVA of 20/40 or better was 37.8% with an average 51.8 ± 4.9 (confidence interval: 42.0-61.5) months of follow-up. Half of the patients in our study achieved the minimum visual acuity required for binocular functioning, whereas one-third of the patients achieved a BCVA somewhat similar to that of the contralateral eye. The complications were similar to those reported previously with good retention of the device. BKPro implantation is a reasonable option for patients with good vision in the fellow eye.

Boston type 1 keratoprosthesis for primary congenital glaucoma

Background/aimsTo evaluate the Boston type 1 keratoprosthesis (KPro-1) in treatment of eyes with primary congenital glaucoma.MethodsA retrospective review was performed of every eye with congenital glaucoma that was treated with...

Boston Keratoprosthesis: Outcomes and Complications: A Report by the American Academy of Ophthalmology

To review the published literature on safety and outcomes of the Boston type I keratoprosthesis (BI-KPro) for the surgical treatment of corneal opacification not amenable to human cadaveric corneal transplantation. Searches of peer-reviewed literature were conducted in PubMed and the Cochrane Library in December 2012, July 2013, and January 2014 without date restrictions. The searches were limited to studies published in English and yielded 587 citations. The abstracts of these articles were reviewed, 48 articles were selected for possible clinical relevance, and 22 were determined to be relevant for the assessment objectives. Nine studies were rated as level II evidence and 13 studies were rated as level III evidence. Excluded were level III evidence, case reports, review articles, letters, editorials, and case series with fewer than 25 eyes. In 9 articles, a best-corrected Snellen visual acuity (BCSVA) of 20/200 or better occurred in 45% to 89% of eyes. Five articles described a BCSVA of 20/50 or better in 43% to 69% of eyes, and 4 articles found a BCSVA of 20/40 or better in 11% to 39% of eyes. Retention rates of the BI-KPro ranged from 65% to 100%. Reasons for loss of vision after BI-KPro implantation most commonly included corneal melts resulting from exposure keratopathy, endophthalmitis, and infectious keratitis or corneal ulceration. The 2 most common complications after surgery were retroprosthetic membrane formation (range, 1.0%-65.0%; mean ± standard deviation [SD], 30.0±19.0%) and elevated intraocular pressure (range, 2.4%-64.0%; mean ± SD, 27.5±18.1%). The 2 most common posterior segment complications were endophthalmitis (range, 0%-12.5%; mean ± SD, 4.6±4.6%) and vitritis (range, 0%-14.5%; mean ± SD, 5.6±4.7%). The reviewed articles on BI-KPro use suggest that the device improves vision in cases of severe corneal opacification that were not amenable to corneal transplantation using human cadaveric keratoplasty techniques. A number of severe anterior and posterior segment complications can develop as follow-up continues, making ongoing close observation paramount for patients undergoing this surgery. These complications include infection, device extrusion, and permanent vision loss.

Primary implantation of type I Boston keratoprosthesis in nonautoimmune corneal diseases.

The aim of this study was to report outcomes of type I Boston keratoprosthesis (KPro) as primary corneal surgery in nonautoimmune corneal disorders. In this retrospective, observational, large single-center case series of 43 eyes (37 patients) that were followed for an average of 39 months (1-6 years), primary implantation of the type I Boston KPro was performed in all patients. Visual acuity at year 1, visual acuity at last follow-up, and postoperative complication rates were examined for all eyes. Preoperative best-corrected visual acuity ranged from 20/60 to light perception, with vision of 20/200 or worse in 88%. Vision was ≥20/200 at 1 year in 77% of eyes (P < 0.0001). Complications included retroprosthetic membrane formation (51%), glaucoma progression (47%), corneal melt (19%), and sterile vitritis (14%). In a large series with long follow-up, primary Boston KPro effectively restored vision. Close follow-up is needed to manage the known complications after Boston KPro.

T-style keratoprosthesis based on surface-modified poly (2-hydroxyethyl methacrylate) hydrogel for cornea repairs.

Corneal disease is a common cause of blindness, and keratoplasty is considered as an effective treatment method. However, there is a severe shortage of donor corneas worldwide. This paper presents a novel T-style design of a keratoprosthesis and its preparation methods, in which a mechanically and structurally effective artificial cornea is made based on a poly(2-hydroxyethyl methacrylate) hydrogel. The porous skirt was modified with hyaluronic acid and cationized gelatin, and the bottom of the optical column was coated with poly(ethylene glycol). The physical properties of the T-style Kpro were analyzed using ultraviolet and visible spectrophotometry and electron scanning microscopy. The surface chemical properties were characterized using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The surface modification in the spongy skirt promoted cell adhesion and produced a firm bond between the corneal tissue and the implant device, while the surface modification in the optic column resisted cell adhesion and prevented retroprosthetic membrane formation. Through improved surgical techniques, the novel T-style keratoprosthesis provides enough mechanical stability to facilitate long-term biointegration with the host environment. In vivo implantation experiments showed that the T-style keratoprosthesis is a promising cornea alternative for patients with severe limbal stem cell deficiency and corneal opacity.

Histopathological and immunohistochemical analysis of melt-associated retroprosthetic membranes in the Boston type 1 keratoprosthesis.

Retroprosthetic membrane (RPM) formation is the most common complication associated with the Boston type 1 keratoprosthesis and has been associated with corneal melt. To identify the histological and immunohistochemical characteristics of RPMs associated with corneal melt. Observational histopathological case series at a tertiary eye care referral center among patients who underwent Boston type 1 keratoprosthesis explantation because of donor corneal melt at the Illinois Eye and Ear Infirmary between January 1, 2011, and January 1, 2012. Seven RPM specimens from 7 eyes were stained with hematoxylin-eosin, cytokeratin 7, cytokeratin AE1/3, smooth muscle actin, vimentin, and CD34. Light microscopy was used to evaluate specimens for inflammation and epithelial ingrowth. XY-karyotyping using fluorescence in situ hybridization was performed on 4 specimens with known donor-recipient sex mismatch. Histological and immunohistochemical characteristics of RPMs. Inflammatory cells were present in 4 of 7 RPMs. In 3 of 4 sex-mismatched specimens, tissue XY-karyotyping of the RPM interphase cells was consistent with the host sex karyotype. The fourth specimen showed a mixture of recipient-type and donor-type cells. Melt-associated RPMs show variable degrees of inflammation. Most membranes seem to originate from a proliferation of host cells, but donor tissue may contribute in some cases.

Long-term Outcomes of Boston Type 1 Keratoprosthesis Implantation: A Retrospective Multicenter Cohort

To study the long-term outcomes of Boston type 1 keratoprosthesis (KPro) surgery. Retrospective, multicenter case series. A total of 158 eyes of 150 patients underwent KPro implantation at 5 participating tertiary centers in the United States between January 2003 and December 2006. Of those, 139 eyes of 133 patients were included in the analyses. The medical records of consecutive adult patients who received KPro surgery were reviewed. All patients with at least 1 postoperative visit were retained in the outcomes analyses. In eyes in which a repeat KPro procedure was performed, only the outcomes of the initial surgery were analyzed. Visual acuity (VA) outcomes, postoperative complications, and device retention. The mean follow-up was 46.7 ± 26 months with all but 4 eyes having at least 6 months of follow-up. Preoperatively, only 10.8% of the eyes had VA of ≥ 20/200. Postoperatively, the VA in 70% of eyes improved to ≥ 20/200. The probability of maintaining VA of ≥ 20/200 at 7 years was 50%. The device retention rate was estimated at 67% at 7 years. The 7-year cumulative incidence of complications was 49.7% for retroprosthetic membrane formation, 21.6% for glaucoma surgery, 18.6% for retinal detachment, and 15.5% for endophthalmitis. Although the risk for complications with longer follow-up seemed to increase, this large multicenter cohort demonstrates favorable outcomes with KPro, with a large number of patients achieving and retaining useful vision over a 7-year period.