Retroprosthetic Membrane Research Articles

Treatment of Aniridia With Boston Type I Keratoprosthesis

To report the outcomes of Boston keratoprosthesis (K-pro) type I implantation for congenital aniridia. A retrospective review of the medical records of every patient with congenital aniridia who underwent Boston K-pro type I implantation at the University of Iowa Hospitals and Clinics from January 1, 2009, through December 31, 2011 was performed. The main outcome measures were visual acuity, graft retention, and postoperative complications. A total of 7 eyes (7 patients) met the inclusion criteria. The mean patient age was 52 years (range, 12-85 years). The preoperative visual acuity was 20/1600 in 6 eyes (85.7%) and hand motions in 1 eye (14.3%). After a median follow-up period of 18 months (range, 3-30 months), the median final best spectacle-corrected visual acuity was 20/200 (range, 20/100 to light perception). This included 2 eyes (28.6%) that were 20/100 and 5 eyes (71.4%) that were better than 20/300. Compared with the preoperative best spectacle-corrected visual acuity, the final vision was improved in 6 eyes (85.7%) and worse in 1 eye (14.3%). The K-pro graft was retained in all 7 eyes (100%). The most common complication was the formation of a retroprosthetic membrane in 3 eyes (42.9%), none of which required either a YAG capsulotomy or a vitrectomy. One eye (14.3%) developed a wound dehiscence that required surgical repair. The Boston K-pro type I is a good option for the visual rehabilitation of eyes with congenital aniridia.

Retention of the Boston Keratoprosthesis Type 1: Multicenter Study Results

To report the retention rate of the Boston keratoprosthesis type 1 and to identify risk factors for keratoprosthesis loss. Cohort study. A total of 300 eyes of 300 patients who underwent implantation of the Boston keratoprosthesis type I device between January 2003 and July 2008 by 19 surgeons at 18 medical centers. Forms reporting preoperative, intraoperative, and postoperative parameters were prospectively collected and subsequently analyzed at a central data collection site. Keratoprosthesis retention. A total cumulative number of 422 life-years of device implantation are included in this analysis. The average duration of follow-up was 17.1 ± 14.8 months, with a range of 1 week to >6.1 years. Ninety-three percent of the 300 Boston keratoprosthesis implants were retained at their last follow-up, corresponding to a retention time of 396 patient-years or 1.42 years/keratoprosthesis. The probability of retention after 1 year and 2 years was 94% and 89%, respectively. During the study period, 21 (7%) eyes failed to retain the device; the reasons for keratoprosthesis loss include sterile keratolysis (9), fungal infections (8), dense retroprosthetic membranes (3), and bacterial endophthalmitis (1). Multivariate analysis demonstrated 3 independent risk factors for keratoprosthesis loss: autoimmune cause (hazard ratio [HR], 11.94; 95% confidence interval [CI], 3.31-43.11), ocular surface exposure requiring a concomitant tarsorrhaphy (HR, 3.43; 95% CI, 1.05-11.22), and number of prior failed penetrating keratoplasties (HR, 1.64; 95% CI, 1.18-2.28). The Boston keratoprosthesis type 1 seems to be a viable option for eyes that are not candidates for penetrating keratoplasty (PK). Ocular surface disease due to an autoimmune cause demonstrated the lowest retention rate. The author(s) have no proprietary or commercial interest in any materials discussed in this article.

La kératoprothèse Alphacor™ : dispositif, technique chirurgicale et résultats cliniques

Clinical evaluation of Alphacor keratoprosthesis in patients at high risk of corneal allograft rejection. Retrospective case series. Alphacor implantation was performed via a two-step procedure with intrastromal insertion followed by secondary exposure of the optic after 6 months. Visual acuity and occurrence of postoperative complications were evaluated. Fourteen eyes of 14 patients underwent Alphacor keratoprosthesis implantation. Mean follow-up was 15.6 ± 5.6 months (from 2 to 24 months). Postoperative mean visual acuity gain was 2.5 ± 3.1 lines (from 0 to +11 lines). Visual acuity was superior or equal to 20/200 in 21% of cases. Seven cases of stromal melt (50%) occurred, of which one case (7.1%) experienced spontaneous extrusion of the implant, three cases (21.4%) required tectonic penetrating keratoplasty, and three patients underwent lamellar keratoplasty on top of the implant. Three cases (21.4%) of retroprosthetic membrane were observed and successfully managed. One patient (7.1%) developed late endophthalmitis. Alphacor is an alternative to corneal allograft in cases of corneal blindness at high risk of allograft failure. Throughout the preoperative evaluation, it is imperative to take into account the limitations of this keratoprosthesis in terms of indications, and additional studies are necessary in order to determine and refine the optimal surgical technique for implantation as well as the efficacy of postoperative treatments.

Boston type 1 keratoprosthesis outcomes in ocular burns

To report the outcomes of Boston type I keratoprosthesis (BKPro) in the management of ocular burn injuries. 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. 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. 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.

Post-surgical visual outcome and complications in Boston type 1 keratoprosthesis

ObjectiveTo describe the visual outcome of patients who underwent Boston type 1 keratoprosthesis (KPro1) implantation, and describe serious sight-threatening post-operative complications. MethodsWe performed an analysis of the clinical records of all patients who underwent Boston keratoprosthesis implantation (BKI) in our institution from May 2006 to February 2011. ResultsA total of 41 eyes of 37 patients were included in the final analysis, of whom 22 (59.45%) were male and 15 were (40.54%) female. The mean age was 56.44 years (range 2–90). The most frequent diagnoses were bullous keratopathy, autoimmune diseases, such as Stevens–Johnson syndrome (SJS)/Lyell syndrome (LS), and aniridic keratopathy. The mean number of previous keratoplasties (PK) was 2.36 (range 0–8), and the mean number of previous non-PK surgeries was 1.58 (range 0–9). The mean follow-up time was 22.17 months (range 3–46). The mean best corrected visual acuity (BCVA) logMAR before surgery was 2.05 (range 1.10–2.52), and the mean best corrected visual acuity achieved after surgery was 1.16 (range 0.08–2.70). The most frequent complication was the formation of retroprosthetic membrane (RPM) which appeared in 22 (53.65%) eyes. Of these, 6 (27.27%) appeared after another surgery. Fourteen (63.63%) RPM required treatment, an average of 1.71 (range 1–4) laser YAG applications were performed, and surgical membranectomy was performed in 3 patients. Eleven (26.82%) eyes showed chorioretinal adhesion problems, 6 (14.63%) of which occurred after follow-up of BKI surgery. Infectious complications occurred in 7 (17.07%) cases; 2 (4.87%) patients had infectious keratitis and 5 (12.19%) endophthalmitis. ConclusionsVisual function improved in most patients. Those with prior multiple ocular surgeries and alterations of systemic immunity such as SJS, LS, and diabetes mellitus are at increased risk for serious sight-threatening complications, such as RPM, chorioretinal detachment and infection. Nevertheless, we consider KPro as an effective alternative in patients with multiple ocular pathology and imminent risk of rejection of a new KP.

Retroprosthetic Membrane and Risk of Sterile Keratolysis in Patients With Type I Boston Keratoprosthesis

To evaluate whether retro-backplate retroprosthetic membrane is correlated with risk of melt in patients with a type I Boston Keratoprosthesis (KPro). Retrospective, observational case series. Study of 50 eyes of 47 patients with type I Boston KPro and postoperative anterior segment optical coherence tomography (AS OCT) imaging performed at the University of Illinois at Chicago. Main outcome measures were presence of retro-backplate membrane and development of melt requiring explantation. For eyes with melt, membrane thickness was measured using the AS OCT images obtained at the last visit before melt occurred. For eyes without melt, the last available AS OCT images were used for measurement. AS OCT evidence of a retro-backplate membrane was observed in 100% of eyes that melted and in 34.1% of eyes that did not (P = .0034; risk ratio, 2.9; 95% confidence interval, 1.9 to 4.4). Retro-backplate membrane thickness in the melt group was 278 μm versus 193 μm in the nonmelt group (P = .025). The retro-backplate portion of a retroprosthetic membrane is to be differentiated from the retro-optic portion seen at the slit lamp. The retro-backplate membrane as shown by AS OCT imaging is correlated with an increased risk of sterile keratolysis, possibly because of impedance of nutritional support from the aqueous humor. Further studies are needed to better standardize the AS OCT measurements of retro-backplate membranes as well as to identify early interventions to prevent progression of thin membranes once identified on AS OCT.

Ceratoprótese de Boston

A short review of type 1 Dohlman-DoaneKeratoprosthesis (KPro) addresses results and complications. Dohlman-DoaneKPro is today a good option for cases of corneal blindness with poor prognosis for traditional penetrating keratoplasty. KPro design and surgical improvements along with proper preoperative ocular surface condition allows good results in non-immune diseases. Main complications of this KPro areinflammatory retroprosthetic membrane, glaucoma, corneal melting,vitreitis, and infection (keratitis and endophthalmitis). Comprehensive long-term postoperative follow-up examinationsare needed to monitor for and prevent serious complications.

Visual Outcomes of Boston Keratoprosthesis Implantation as the Primary Penetrating Corneal Procedure

To report the short-term visual outcomes and complications of keratoprosthesis surgery as the primary penetrating corneal procedure for patients at high risk for conventional corneal transplantation. A retrospective chart review was conducted of 21 eyes of 19 patients who underwent either Boston keratoprosthesis type I or type II as the primary penetrating corneal procedure from February 2007 to March 2011. Nineteen type I (90.5%) and 2 type II (9.5%) Boston keratoprosthesis procedures were performed in 19 patients. Mean follow-up was 14.6 months (range, 6-36.3 mo). Primary indications for surgery included chemical or thermal injury, aniridia, and Stevens-Johnson syndrome. Preoperative best-corrected visual acuity (BCVA) ranged from 20/100 to light perception and was count fingers or worse in 20 eyes (95.2%). At last follow-up for all eyes, 15 eyes (71.4%) achieved BCVA≥20/200 and 4 eyes (19%) improved to BCVA≥20/50. No intraoperative complications occurred. Postoperative complications include retroprosthetic membrane formation (47.6%), cystoid macular edema (33.3%), elevated intraocular pressure (23.8%), glaucoma progression (14.3%), and endophthalmitis (4.8%). The initial keratoprosthesis was retained in 19 eyes (90.5%). The Boston keratoprosthesis, based on early follow-up, is a good alternative as a primary penetrating corneal procedure in a select group of patients with very poor prognosis for penetrating keratoplasty. Although complications can occur and require close monitoring, visual acuity significantly improved in the majority of patients.

Pronóstico visual y complicaciones posquirúrgicas en queratoprótesis de Boston tipo 1

ObjectiveTo describe the visual outcome of patients who underwent Boston type 1 keratoprosthesis (KPro1) implantation, and describe serious sight-threatening post-operative complications. MethodsWe performed an analysis of the clinical records of all patients who underwent Boston keratoprosthesis implantation (BKI)in our institution from May 2006 to February 2011. ResultsA total of 41 eyes of 37 patients were included in the final analysis, of whom 22 (59.45%) were male and 15 were (40.54%) female. The mean age was 56.44 years (range 2-90). The most frequent diagnoses were bullous keratopathy, autoimmune diseases, such as Stevens-Johnson syndrome (SJS)/Lyell syndrome (LS), and aniridic keratopathy. The mean number of previous keratoplasties (PK) was 2.36 (range 0-8), the mean number of previous non-PK surgeries was 1.58 (range 0-9). The mean follow-up time was 22.17 months (range 3-46). The mean best corrected visual acuity (BCVA) logMAR before surgery was 2.05 (range 1.10-2.52), and the mean best corrected visual acuity achieved after surgery was 1.16 (range 0.08- 2.70). The most frequent complication was the formation of retroprosthetic membrane (RPM) which appeared in 22 (53.65%) eyes. Of these, 6 (27.27%) appeared after another surgery. Fourteen (63.63%) RPM required treatment, an average of 1.71 (range 1-4) laser YAG applications were performed, and surgical membranectomy was performed in 3 patients. Eleven (26.82%) eyes showed chorioretinal adhesion problems, 6 (14.63%) of which occurred after follow-up of BKI surgery. Infectious complications occurred in 7 (17.07%) cases; 2 (4.87%) patients had infectious keratitis and 5 (12.19%) endophthalmitis. ConclusionsVisual function improved in most patients. Those with prior multiple ocular surgeries and alterations of systemic immunity such as SJS, LS, and diabetes mellitus are at increased risk for serious sight-threatening complications, such as RPM, chorioretinal detachment and infection. Nevertheless, we consider KPro as an effective alternative in patients with multiple ocular pathology and imminent risk of rejection of a new KP.

Boston Keratoprosthesis in 2012: preventing complications and optimizing outcomes

AbstractPurpose To provide an update on Boston KPro indications, post‐operative care and prevention and management of the complications based upon experience at the MEEI and results presented at the Eighth KPro Study Group Meeting in May 2012.Methods Clinical records were reviewed to determine outcomes of primary KPro surgery and surgery done using backplates of different materials and design. The origin of retroprosthetic membranes (RPM) from 4 explanted KPro’s was determined using immunohistochemistry and light and transmission electron microscopy. Wound anatomy in 6 KPro patients with larger 9.5 mm backplates was evaluated by anterior segment OCT and compared to wound anatomy in patients with standard 8.5 mm backplates.Results Titanium backplates reduce RPM formation. Histopathologic evaluation showed that RPM are fibrous membranes that originate from activated host stromal cells that migrate through gaps in the graft‐host junction, suggesting that better wound apposition may reduce RPM formation. OCT demonstrated that larger backplates clamp the graft‐host junction more effectively than standard backplates, resulting in a thinner graft‐host junction and better wound apposition. Primary Boston KPro surgery provides good outcomes and device retention in situation such as limbal stem cell deficiency where traditional keratoplasty does poorly.Conclusion Indications for the Boston KPro continue to expand as complications are reduced. Primary Boston KPro may be considered in certain circumstances. Strategies for prevention of RPM include titanium backplates and complete apposition of the graft‐host junction using larger KPro backplates.

Boston Keratoprosthesis (Type I): visual prognosis and complications

AbstractPurpose to describe the functional results and sight threatening post‐operative complications of Type I Boston Keratoprosthesis.Methods retrospective descriptive study of Boston Keratoprosthesis patients from two European eye centers.Results A total of 66 eyes were included for analysis. Mean follow‐up time was 28 months. Majority of patients had more than 2 penetrating keratoplasties, primary clinical diagnosis are presented. Mean preoperative best corrected visual acuity was 2.05, mean best ever achieved post‐operative best corrected visual acuity was 1.16 and final mean postoperative best corrected visual acuity was 1.47 . The most common sight‐threatening complications were as follows: retroprosthetic membrane, retinal/choroidal detachment, infectious keratitis, endophthalmitis, peripheral retinal occlusive vasculitis and prosthesis extrusion. Management of complications are discussed.Conclusion 95 % retention rate with overall improvement in visual acuity demonstrates that Type I Boston Keratoprosthesis is a good alternative to cases of multiple graft failure due to various primary clinical diagnoses. Complications must be detected early on and managed accordingly to ensure success of the procedure.

Chronic Hypotony Associated With the Boston Type 1 Keratoprosthesis

To report the occurrence of chronic hypotony as a complication following Boston type 1 keratoprosthesis (KPro) implantation and to determine associated risk factors. Retrospective case series. The medical records of all patients undergoing KPro implantation between January 2004 and November 2010 at the Wilmer Eye Institute were reviewed. Patients who developed chronic hypotony following Boston type 1 KPro implantation not attributable to anatomic problems (eg, retinal detachment, overfiltering glaucoma tube shunts, tissue necrosis with aqueous leak) or other causes were identified. Demographics and preoperative, intraoperative, and postoperative clinical findings were analyzed. Light microscopic examination of an enucleated globe as well as fibrous retroprosthetic membranes excised at the time of vitrectomy from another patient was performed. Sixty-eight eyes received KPro implantation over the study period. Six eyes experienced chronic hypotony, with a median time of 18.5 months between KPro implantation and the onset of hypotony. The incidence of chronic hypotony in this series was calculated to be 3.7% at 1 year (95% CI = 0.9%-14.0%) and 13.3% at 2 years (95% CI = 5.5%-30.0%). Of the 6 eyes that developed chronic hypotony, 5 had a previous history of glaucoma or ocular hypertension, but only 3 had a glaucoma drainage implant. All eyes progressing to chronic hypotony were noted to have a retroprosthetic membrane prior to the onset of hypotony. Cox regression modeling demonstrated an increased risk of chronic hypotony in eyes with retroprosthetic membranes (P < .01) but no increase in risk for older patients (P > .1), eyes with glaucoma drainage implants (P > .5), or a previous history of multiple donor corneal transplants (P > .5). Chronic hypotony can be a significant complication of KPro implantation and should be assessed carefully in eyes with retroprosthetic membranes. Further study of an association between hypotony and retroprosthetic membrane formation may be useful to gain insight into the mechanism of this complication and potential prevention or treatment options.

International Results with the Boston Type I Keratoprosthesis

To determine the indications and outcomes of Boston type 1 keratoprosthesis (Massachusetts Eye and Ear Infirmary, Boston, MA) surgery performed outside of North America and to compare them with those obtained in the United States by the surgeon who trained the international surgeons. Retrospective review of consecutive clinical case series. One hundred ninety-four patients (223 keratoprosthesis procedures performed in 205 eyes) who received Boston type 1 keratoprosthesis at 11 ophthalmology centers in Armenia, India, Indonesia, Nepal, Philippines, Russia, and Saudi Arabia between May 1, 2006, and July 1, 2011 (international series), and at the Jules Stein Eye Institute between May 1, 2004, and July 1, 2011 (University of California, Los Angeles [UCLA] series). Data were collected for each procedure regarding the preoperative characteristics of each eye, the surgical procedure(s) performed, and the postoperative outcomes. Statistical analysis was performed to identify significant differences between the international and UCLA series in terms of retention and complications. Interval visual acuities, keratoprosthesis retention, and significant postoperative complications. In the international series, 113 Boston type I keratoprostheses were implanted in 107 eyes of 100 patients. The most common indication for surgery was corneal graft failure (n = 50; 44%) followed by chemical injury (n = 30; 27%). Although only 2% of eyes had a preoperative corrected distance visual acuity (CDVA) of 20/20 to 20/200, 70%, 68%, and 59% of eyes had a postoperative CDVA of 20/20 to 20/200 at 6 months, 1 year, and 2 years after surgery, respectively. Ninety-one of the 113 keratoprostheses implanted (80.5%) were retained at a mean follow-up of 14.2 months, for a retention failure rate of 22 per 134.6 eye-years (0.163/eye-year). The most common postoperative complications were retroprosthetic membrane formation (27%) and sterile corneal necrosis (18%). The only postoperative complication that was more common in the international series than in the UCLA series was infectious endophthalmitis, which developed in 9% of eyes. Boston keratoprosthesis is a viable means of managing repeat graft failure and ocular chemical injury outside of North America, with similar visual acuity outcomes, retention rates, and incidence rates of postoperative complications to those obtained by North American surgeons.

Boston Keratoprosthesis Type 1 Surgery

This study aims to determine whether frozen corneas can be successfully used as carriers of the Boston keratoprosthesis (KPro). Prospective study of 37 patients undergoing KPro surgery with fresh or frozen corneas as carriers. Patients were randomized to receive either a fresh corneal graft or a frozen corneal graft during implantation of the Boston KPro. The randomization depended on availability of fresh versus frozen corneas offered by the local eye bank. All surgeries were performed by the same experienced surgeon. Outcome measures included retention of the device, level of preoperative and postoperative visual acuities (VAs), and complications. The indication for Boston KPro was corneal graft failure in 24 eyes; 13 patients had KPro as a primary procedure. The assembly of the Boston KPro and surgery were uneventful in all cases. Mean follow-up was 9.65 months. Median preoperative VA was counting fingers (range, 20/100 to light perception) in the fresh cornea group (19 eyes) and hand motions (range, 20/150 to light perception) in the frozen cornea group (18 eyes). Median postoperative VA were 20/150 (range, 20/30 to hand motions) and 20/150 (range, 20/40 to counting fingers) in the fresh and frozen cornea groups, respectively. Inflammation and retroprosthetic membrane formation were the most common complications with similar rates between the 2 groups. The device retention rate was 100% at the end of the follow-up period. Frozen and fresh corneal donors seem equally efficient and safe as carriers of the Boston KPro with similar recuperation of VA and no untoward complications, such as melt, leaks, or endophthalmitis.

Risk Factors for the Development of Retroprosthetic Membranes with Boston Keratoprosthesis Type 1: Multicenter Study Results

The purpose of this study was to identify possible risk factors for retroprosthetic membrane (RPM) development in a large, multicenter cohort of patients receiving a Boston type 1 keratoprosthesis. Cohort study. The final analysis included 265 eyes of 265 patients who underwent implantation of a Boston keratoprosthesis type I device between January 2003 and July 2008 by 1 of 19 surgeons at 18 medical centers. Forms reporting preoperative, intraoperative, and postoperative parameters were prospectively collected and subsequently analyzed at a central data collection site. The primary outcome was the presence or absence of an RPM during the follow-up period. The average age of patients was 63.3±19.1 years, 48.5% of the patients were female, and 52.5% of procedures were performed on the right eye. The mean follow-up time was 17.8±14.9 months. The majority (85.4%; n = 222) had undergone an average of 2.2±1.2 (range, 1-8) penetrating keratoplasties before keratoprosthesis implantation, and 38 eyes (14.6%) received a primary keratoprosthesis. The overall RPM formation rate was 31.7% (n = 84). The most significant risk factor for RPM development was infectious keratitis (as a surgical indication for keratoprosthesis surgery itself), resulting in a rate of RPM formation of 70.6%. As an independent risk factor, the hazard ratio (HR) of RPM development in these eyes was 3.20 (95% confidence interval, 1.66-6.17). Aniridia was also an independent risk factor for RPM development (HR, 3.13; 95% confidence interval, 1.10-8.89). Formation of RPM is a common complication of keratoprosthesis surgery, occurring in approximately one-third of cases. Eyes at the highest risk of RPM development are those receiving corneal replacement for infectious keratitis and aniridia.

Glaucoma Associated With Boston Type I Keratoprosthesis

To evaluate outcomes of the Boston type I keratoprosthesis (KPro) and associated incidence of glaucoma. Retrospective cohort study. All patients who underwent KPro surgery at 1 institution from 2003 to 2009 with at least 3 months of follow-up. Preoperative visual acuity, diagnosis, history of glaucoma, and intraoperative and postoperative parameters were recorded. Statistical analysis was performed to identify factors that may influence increase in intraocular pressure (IOP) and glaucoma development or progression after surgery. Best-corrected visual acuity (BCVA), IOP, postoperative medical and surgical treatments for glaucoma, and KPro retention and complications. Thirty-six KPro procedures were performed in 30 eyes of 29 patients with a mean (±SD) follow-up of 17 ± 19 months (range, 3-67 months). The main indication for KPro implantation was corneal graft failure (77%). Primary KPro procedures were performed in 23% of eyes for limbal stem cell deficiency secondary to chemical burns and aniridia and for herpetic disease. Median preoperative BCVA was hand motions with an overall improvement to 20/330 (range, 20/20 to hand motions) at 9 months postoperatively; mean BCVA was 20/600 (range, 20/40 to NLP) at the last follow-up. Twenty eyes (67%) had a preoperative history of glaucoma, with 8 of those eyes (40%) having undergone previous glaucoma surgery. Twenty-one eyes (70%) underwent concomitant glaucoma surgery. Postoperative increased IOP (22 mm Hg or higher) was noted in 15 eyes (50%), although definite glaucoma development or progression was noted in 7 of those 15 eyes (23% of total eyes). Mean BCVA at the last follow-up in eyes with glaucoma development or progression was 3/200 compared with 20/563 in the remaining 23 eyes. Six patients (20%) required repeat KPro implantation, and retroprosthetic membranes developed in 23 eyes (77%). No patient had vitritis or infectious endophthalmitis develop. The Boston type I KPro is an effective option for management of eyes with poor prognosis for primary or repeat penetrating keratoplasty. Visual potential is limited by preoperative comorbidities; however, glaucoma development or progression of preexisting glaucoma is a significant cause of postoperative visual loss. Rigorous perioperative management of elevated IOP is essential for long-term success of KPro surgery.

Short-term visual outcomes of Boston keratoprosthesis type i in Saudi Arabia

Purpose:To evaluate the visual outcomes, complications and retention of threadless type I Boston keratoprosthesis (KPro) in Saudi Arabia.Materials and Methods:Retrospective analysis of four eyes of four patients (one female and three males; age range: 48 to 72 years) who underwent Boston type I threadless KPro implantation between January and December 2009.Results:In the median follow-up of 11 months (range 6 to 14 months), visual outcomes were satisfactory. Preoperative diagnosis included two patients of post-trachoma dense vascularized corneal scarring, one patient of corneal alkali burn and one patient of repeated failed corneal grafts. All patients demonstrated significant improvement in vision; with pre-operative visual acuity of hand movements (HM), counting fingers and HM improved to best corrected visual acuity (BCVA) of 20/200, 20/60, 20/50 and 20/30 on their last follow-up visits respectively. None of the patients developed glaucoma as a result of the procedure. No retro-prosthetic membrane developed till the last follow-up visit. One of the four patients had a corneal melt (due to severe dryness associated with trachoma) 6 months after the KPro implantation and underwent a successful KPro revision. Despite the relatively poor prognosis expected in alkali burn eye, the patient attained the maximum BCVA (20/30) of the four eye series on the last follow-up visit at six months.Conclusion:In consistent with the earlier reports from other parts of the world, all the 4 eyes had a significant increase in vision after Boston type I KPro implantation. However, patients require close lifelong follow-up to manage any complications.

Boston type 1 keratoprosthesis: the New York Eye and Ear experience

The Boston keratoprosthesis has had variable success rates in the past. However, significant modifications to design and management have recently led to successful outcomes. This study was undertaken to evaluate the outcomes of the Boston type 1 keratoprosthesis at our institution. A retrospective chart review was performed of all Boston type 1 keratoprosthesis procedures conducted at a single practice at the New York Eye and Ear Infirmary from December 2006 to August 2010. Outcome measures included visual acuity, retention rates, and complications. In all, 58 eyes of 51 patients who received a Boston type 1 keratoprosthesis were included. The most common indication for the keratoprosthesis was failed penetrating keratoplasty (PK) (81.0%; mean 2.4±1.3 PKs per eye). Glaucoma was the most common comorbidity (75.9%). Pre-operative best corrected visual acuity (BCVA) was <20/400 in 87.9% of eyes. At last follow-up, 43.1% of eyes had a BCVA of 20/200. Retention rate was 87.9% over an average follow-up of 21.5±11.4 months (median 22 months, range 3-47 months). Complications increased with time, with 65.5% of eyes experiencing at least one event by 6 months and 75.9% by 1 year. The most common post-operative complication was retroprosthetic membrane formation (50.0%). The Boston type 1 keratoprosthesis provides visual recovery for eyes with multiple PK failures or with poor prognosis for primary PK, showing excellent retention rates. However, there is a trend towards a decline in visual acuity with time and the development of late complications, highlighting a need for longer-term studies.

The Boston Keratoprosthesis in the Management of Corneal Limbal Stem Cell Deficiency

To report the outcomes of the Boston type I keratoprosthesis (Massachusetts Eye and Ear Infirmary, Boston, MA) in the management of corneal limbal stem cell deficiency (LSCD). A retrospective review of all cases of keratoprosthesis implantation performed by a single surgeon (A.J.A.) between May 1, 2004, and March 31, 2010. Procedures performed for the management of LSCD were identified, and data were collected regarding the patients' ocular history, surgical procedure(s) performed, and postoperative outcomes, including interval visual acuities, retention, complications, and required surgical procedures. The outcome data from patients with LSCD were compared with those of individuals who underwent keratoprosthesis implantation for indications other than LSCD. Twenty-eight keratoprostheses were performed in 23 eyes of 22 patients with LSCD. The most common indications for surgery were chemical injury (7 eyes) and Stevens-Johnson syndrome (6 eyes). Preoperative corrected distance visual acuity (CDVA) was better than counting fingers in 4% of eyes with LSCD and in 9% of eyes without LSCD. Postoperative CDVA was 20/50 or better in 69%, 88%, and 67% of eyes with LSCD at 1, 2, and 3 years after keratoprosthesis implantation, respectively. Each of these percentages is higher than the percentage of eyes without LSCD obtaining CDVA of 20/50 or better at each time point. Whereas the retention failure rate in eyes with LSCD (0.148/eye-year) was higher than the rate in eyes without LSCD (0.114/eye-year), when eyes with Stevens-Johnson syndrome were excluded from the LSCD group, the non-Stevens-Johnson syndrome LSCD retention failure rate (0.056/eye-year) was half that of the non-LSCD group. The most common postoperative complications in eyes with LSCD were persistent corneal epithelial defect (PED) formation (56.5% of eyes) and sterile corneal necrosis (30%), whereas retroprosthetic membrane formation (46%) was the most common postoperative complication in eyes without LSCD, followed by PED formation (23%). The development of a PED was found to be a significant risk factor for sterile corneal stromal necrosis and infectious keratitis. Boston type I keratoprosthesis implantation results in a significant improvement in CDVA in the majority of patients with LSCD, with CDVA of 20/50 or better in more than two-thirds of eyes up to 3 years after surgery. PED formation is the most common postoperative complication in eyes with LSCD and is associated with an increased rate of sterile stromal necrosis and a lower retention rate in eyes undergoing keratoprosthesis implantation for immune-mediated LSCD. These results support the use of the Boston type I keratoprosthesis in managing bilateral, non-immune-mediated LSCD.

Boston Keratoprosthesis for Keratopathy in Eyes With Retained Silicone Oil: A New Indication

To analyze the visual outcome of Boston keratoprosthesis for keratopathy in silicone oil-filled eyes. Retrospective chart review of patients with silicone oil-induced keratopathy undergoing Boston keratoprosthesis between January 2008 and June 2010 was performed. Patients received Boston keratoprosthesis as the primary procedure or after a failed penetrating keratoplasty because of silicone oil-induced keratopathy after assessing possible visual potential. Silicone oil had to be retained in all eyes because of persistent ocular hypotony. Of the 8 eyes that underwent surgery, anatomic retention and visual improvement were noted in 7 eyes (87.5%). The visual acuity improved to 20/200 or better in 6 eyes (66.67%). Repeated corneal melt necessitated the removal of the prosthesis with corneal transplant in 1 eye. Membranectomy was performed twice for retroprosthetic membrane in 1 eye. Boston keratoprosthesis seems to be a viable option for visual rehabilitation in postvitrectomized eyes with a decrease in vision due to retained silicone oil-induced keratopathy.