Incidence, Risk Factors, and Surgical Management of Boston Type 1 Keratoprothesis Corneal Melts, Leaks, and Extrusions

Boston Keratoprosthesis type 1 (KPro) without contact lens wearing in end-stage corneal disease: The APEC experience

PURPOSE

To report the visual outcomes and survival analysis of keratoprosthesis without contact lens wearing in a tertiary eye care hospital in Mexico City, Asociación Para Evitar La Ceguera (APEC, Coyoacán, México).

DESIGN

Retrospective cohort with survival analysis.

PARTICIPANTS

Twenty-three eyes (22 patients) received KPro type 1 between 2015 and 2020 with a follow-up time of three years.

METHODS

We included analyzed data about past medical history, preoperative diagnosis, best-spectacle visual acuity (BSCVA), postoperative complications and retention rate. Univariate, bivariate and survival analysis were performed and reported.

RESULTS

The mean age was 58 ± 13.5 years (SD). 60.86% were male patients (14 eyes). Twelve-eyes (52%) achieved a BSCVA of 20/200 or better in the first and second year of follow-up. At 3 years, only 35% achieved 20/200 or better (BSCVA). Retention rate of Boston type 1 KPro was 87% (20 eyes) at 3 years follow-up. The most common complication was retroprosthetic membrane (RPM) which occurred in 9 eyes (39.1%), followed by corneal melting in 7 eyes (30.4%).

CONCLUSIONS

We report the results of a retrospective cohort of twenty-three eyes (22 patients) who were implanted with a Boston type 1 KPro without contact lens wearing to treat corneal blindness. BSCVA improved significantly in most patients achieving 20/200 or better at the 2-year follow-up. Retention rate was 87%, with the presence of RPM as the most common complication.

Dealing With Pericylindrical Melts in Keratoprosthesis: Tenon Patch Graft to the Rescue

PURPOSE

The aim of this study was to describe the outcomes of autologous Tenon patch graft in the management of Auro keratoprosthesis-related pericylindrical corneal melt.

METHODS

We report 3 cases of sterile pericylindrical corneal melt in patients with Auro keratoprosthesis implantation after a mean duration of 5 years (1.5-8 years). Case 1 was a patient with severe graft-versus-host disease. Cases 2 and 3 were cases of chemical injury.All these cases of sterile pericylindrical corneal melt (4-6 mm) underwent autologous Tenon patch graft. The technique included freshening of the edges around the melt, followed by measuring the size of the defect. A Tenon graft harvested from the patient's own eye was used to seal the defect and act as a scaffold. The Tenon patch graft was spread over the melt and held in place by the application of fibrin glue and/or interrupted 10-0 nylon sutures. A bandage contact lens was then placed on the eye.

RESULTS

Tenon patch graft was well taken in all patients. The mean duration of epithelial healing was 1 month. Globe integrity was well maintained with no postoperative complications at a mean follow-up duration of 12 months (6-18 months).

CONCLUSIONS

Corneal melt is one of the most dreaded complications of KPro because its occurrence could threaten visual prognosis and globe integrity. Autologous Tenon patch is a simple yet innovative and effective option to steer such eyes away from potentially dreadful complications.

Why Are Corneal Specialists Resistant to Treating Patients Who Have Severe Ocular Surface Disease With Limbal Stem Cell Deficiency?

PURPOSE

To highlight the paucity of surgeons performing ocular surface stem cell transplantation with systemic immunosuppression (OSSTx with SI) for limbal stem cell deficiency (LSCD) patients, suboptimal treatments for LSCD, and obstacles to adoption.

METHODS

A review of the Eye Bank Association of America annual reports and the authors' case volume for OSSTx with SI was performed. Examination of the published literature on corneal surgeries, especially for LSCD, was completed. These findings were combined with our clinical observations to develop this editorial.

RESULTS

Despite techniques and protocols for OSSTx with SI published more than 30 years ago for the treatment of severe bilateral LSCD, only a small number of corneal specialists have adopted these techniques. There is a paucity of attention to this population of patients, with minimal publications to advance this area of our field. We are too often referred patients with LSCD and severe ocular surface disease that have had suboptimal treatments such as penetrating keratoplasties or primary keratoprostheses. Hesitancy for adopting OSSTx with SI is likely due to a lack of exposure to these procedures during training and fear of systemic immunosuppression. Corneal surgeons are likely unaware of the safety of systemic immunosuppression with appropriate monitoring especially when comanaging these patients with an organ transplant specialist.

CONCLUSION

There is a large unmet need for the treatment of corneal blindness secondary to conjunctival and LSCD. For the vast majority of patients, OSSTx should be the first surgical choice to treat these eyes. We hope major ophthalmology centers will meet this need by building programs, and groups of corneal surgeons should collaborate to create regional centers to make this treatment more accessible to help this population.

Preparing the Ocular Surface for a Boston Keratoprosthesis Type 1 Through En Bloc Minor Salivary Gland Transplantation and Mucous Membrane Grafting in End-Stage Stevens-Johnson Syndrome

PURPOSE

This case describes the successful visual restoration of a patient with end-stage Stevens-Johnson syndrome (SJS) with a severely keratinized ocular surface.

METHODS

This study is a case report.

RESULTS

A 67-year-old man with SJS secondary to allopurinol sought visual rehabilitation options. His ocular surface was severely compromised from sequelae of chronic SJS, leaving him with light perception vision bilaterally. The left eye was completely keratinized with severe ankyloblepharon. The right eye had failed penetrating keratoplasty, limbal stem cell deficiency, and a keratinized ocular surface. The patient declined both a Boston type 2 keratoprosthesis and a modified osteo-odonto keratoprosthesis. Therefore, a staged approach was pursued with (1) systemic methotrexate to control ocular surface inflammation, (2) minor salivary gland transplant to increase ocular surface lubrication, (3) lid margin mucous membrane graft to reduce keratinization, and finally, (4) Boston type 1 keratoprosthesis for visual restoration. After minor salivary gland transplant and mucous membrane graft, the Schirmer score improved from 0 mm to 3 mm with improvement in ocular surface keratinization. This approach successfully restored the vision to 20/60, and the patient has retained the keratoprosthesis for over 2 years.

CONCLUSIONS

Sight restoration options are limited in patients with end-stage SJS with a keratinized ocular surface, aqueous and mucin deficiency, corneal opacification, and limbal stem cell deficiency. This case demonstrates successful ocular surface rehabilitation and vision restoration in such a patient through a multifaceted approach that resulted in successful implantation and retention of a Boston type 1 keratoprosthesis.

Retinal Detachment in Eyes with Boston Type 1 Keratoprosthesis: Surgical Techniques and Mid-Term Outcomes

PURPOSE

To evaluate the mid-term outcomes of pars plana vitrectomy (PPV) performed for retinal detachment (RD) repair after Boston type 1 keratoprosthesis (KPro) implantation.

METHODS

Retrospective chart review of KPro implanted at the Stein Eye Institute presenting with RD and treated by PPV. Functional success was defined as a postoperative visual acuity (VA) maintained within 2 Snellen lines of the CDVA measured before the development of the RD (baseline) and anatomical success as an attached retina after the PPV. Kaplan-Meyer survival analyses were performed.

RESULTS

Among the 224 KPro performed, 28 (15.2%) RD were identified, of which 21 (9.4%) were included. The mean follow-up was 42.5 ± 27.3 months. Vitreoretinal proliferation was present in 18/21 (85.7%) eyes. Surgical techniques were adapted to the complex anterior segment anatomy of KPro eyes. Anatomical success was achieved in 18/21 (85.7%) eyes. Functional success occurred in 17/21 (81.0%) eyes, and 5/21 (23.8%) eyes reached 20/400 or better VA at final follow-up. The KPro was retained in 11/21 (52.4%) eyes. The retention rate decreased from 94.7% at 1 year to 53.5% at 5 years. The most frequent complications were retroprosthetic membrane (47.6%) and corneal melt (23.8%).

CONCLUSION

Modified PPV techniques resulted in relatively good mid-term anatomic, functional, and retention rate outcomes, given the severity of RD at presentation, and the numerous preoperative comorbidities of KPro eyes.

POSTOPERATIVE POSTERIOR SEGMENT COMPLICATIONS AFTER BOSTON TYPE 1 KERATOPROSTHESIS: Incidence, Risk Factors, and Intermediate-Term Outcomes

PURPOSE

To identify the incidence of, risk factors for, and outcomes of posterior segment complications (PSC) after Boston Type 1 keratoprosthesis (KPro) implantation.

METHODS

Retrospective, consecutive case series of KPro procedures at the Stein Eye Institute. Data regarding ocular history, intraoperative details, postoperative management, and outcomes were collected. Eyes with at least one PSC (PSC group) were compared with eyes without PSC (No PSC group), and risk factors for PSC were determined.

RESULTS

Ninety-five PSC occurred in 69/169 eyes (40.8%), at a mean of 20.1 months after KPro implantation (0.01 complications/eye month). The median follow-up after KPro implantation was 44.0 months (range 3.0-174.4). The most common PSC were epiretinal membrane (16.6%), cystoid macular edema (12.4%), vitritis (11.2%), and retinal detachment (9.5%). Previous retinal detachment repair, concomitant intraocular lens removal, postoperative aphakia, and vitritis were risk factors for retinal detachment. Postoperative infectious keratitis was a risk factor for epiretinal membrane, cystoid macular edema, and vitritis. The posterior segment complication group had a significantly higher rate of eyes failing to maintain visual acuity ≥20/200 (HR = 2.28; 95% CI = 1.35-3.85) and KPro retention failure rate (HR = 1.66; 95% CI = 0.95-2.91).

CONCLUSION

Posterior segment complications occur in approximately 40% of eyes after KPro implantation, resulting in reduced visual outcomes and KPro retention.

Keyhole Anterior Lamellar Keratoplasty for Boston Keratoprosthesis Corneal Melt

Corneal melt remains a challenging complication of Boston keratoprosthesis (KPro) and may lead to disastrous consequences such as endophthalmitis, KPro extrusion, and permanent loss of vision. Several procedures have been suggested to repair established melts; however, KPro removal or exchange is often required due to high recurrence. We herein describe a novel surgical technique to repair corneal melt: a lamellar corneal graft is centrally trephined, and a radial cut is extended from the central opening to create a keyhole graft. The graft is draped around the KPro and tightly secured around the central stem. The radial cut is closed with sutures, and the graft is secured into the underlying tissue with fibrin glue and sutures. The graft remains stable with the KPro in place, while the patients maintain a 20/200 vision or better at two years. This technique is a useful alternative for securing KPro and preventing corneal melt recurrence.

Endophthalmitis in Eyes With the Boston Type I Keratoprosthesis: Incidence, Recurrence, Risk Factors, and Outcomes

PURPOSE

To determine the incidence and recurrence of Boston type I keratoprosthesis (KPro)-associated endophthalmitis, and its microbiological profile, risk factors, and outcomes.

METHODS

This is a retrospective study of 158 consecutive KPro procedures with a median follow-up of 78.4 months. Medical charts were reviewed for ocular history, contact lens and topical antibiotic use, visual acuity, and complications. For eyes with endophthalmitis, time to infection, culture results, and recurrences were collected. Cox regression analyses identified risk factors for endophthalmitis and compared the risk for visual failure, KPro retention, and globe loss between eyes with and without endophthalmitis.

RESULTS

The incidence and recurrence rates of endophthalmitis were of 1.7% and 6.0% per procedure-year, respectively. First episodes occurred at a median of 18.6 months. Eight of 18 episodes (44%) were culture positive, isolating mainly Gram-positive bacteria (7 [88%]). Previous ocular burn (hazard ratio: 7.34, 95% confidence interval: 1.91-28.15), infectious keratitis (5.09, 1.70-15.22), corneal melt (4.55, 1.50-13.83), and postoperative contact lens wear (4.19, 1.17-15.04) were risk factors. Eyes with endophthalmitis did not have a higher risk for visual failure (1.74, 0.78-3.91) but were more likely to not retain the KPro (2.81, 1.15-6.88) and undergo evisceration (2.81, 1.15-6.88). All eyes lost ≥ 2 lines of vision during the endophthalmitis episode.

CONCLUSIONS

Endophthalmitis is rare but vision and globe threatening in eyes with KPro. Given the increased associated risk, corneal melts and infectious keratitis must be promptly treated, postoperative contact lenses should be considered on a case-by-case basis, and patients with ocular burns might require more aggressive antimicrobial prophylaxis.

Challenges in management of the Boston Keratoprosthesis Type 1

PURPOSE OF REVIEW

The Boston Keratoprosthesis Type 1 was pioneered by Claes Dohlman several decades ago. Since its inception, the device has undergone multiple revisions to address challenges associated with retroprosthetic membrane formation, retention, extrusion, stromal melt and endophthalmitis. Although visual outcomes and retention rates have improved, challenges, especially glaucoma, remain.

RECENT FINDINGS

The Boston Keratoprosthesis Type I device has seen an increase in popularity because of the improvement in rates of retention and visual rehabilitation. Recent outcome studies have allowed clinicians to identify diagnoses and indications that can lead to more favorable results with the Boston Keratoprosthesis Type I device.

SUMMARY

The Boston Keratoprosthesis Type I device continues to play a vital role in visual rehabilitation for eyes with very low chance of realistic allograft survival -- such as in eyes where corneal grafting is considered high-risk: eyes with corneal limbal stem cell failure, extensive deep corneal stromal neovascularization, and multiple allograft failures. This review article summarizes the perioperative and postoperative challenges, as well as other considerations associated with the device.

[Treatment of vascularized high-risk eyes with a Boston keratoprosthesis]

BACKGROUND

In severely compromised and vascularized high-risk eyes, the Boston keratoprosthesis procedure is often the last treatment option. The transparency of the optics is not impaired by endothelial immune reactions.

METHODS

This review article discusses relevant literature as well as our own data and experiences with the Boston keratoprosthesis in high-risk eyes. The relevant complications as well as the postoperative management are discussed.

RESULTS

In more than 60% of the high-risk eyes a long-term increase in visual acuity can be achieved. Keratoprosthesis retention rates show a variable span with reported mean 5‑year retention rates of 75%. The most common postoperative complications include the formation of a retroprosthetic membrane and keratolysis in up to 50% each. More than 70% of the eyes already suffer from (secondary) glaucoma preoperatively, so that glaucoma surgery is performed simultaneously in at least 20% of cases and in the postoperative course further antiglaucomatous surgery is necessary in up to 31%. Vitreoretinal complications include, in particular, sterile vitritis and infectious endophthalmitis but persistent hypotonia is also described in one third of patients.

CONCLUSION

The Boston keratoprosthesis is an alternative to conventional corneal replacement if the prognosis for allogeneic transplants is poor. Postoperative complications are common; therefore, postoperative management plays an important role. For vascularized high-risk eyes, however, it is often the only remaining option for visual rehabilitation.

Time to achieve best postoperative visual acuity following Boston keratoprosthesis surgery

BACKGROUND/AIMS

To evaluate the time needed for patients with Boston type 1 keratoprosthesis (KPro) to reach their best-corrected visual acuity (BCVA) and all contributing factors.

METHODS

We retrospectively reviewed 137 consecutive eyes from 118 patients, measured how long they needed to reach their BCVA and looked at factors that might affect this time duration including patient demographics, ocular comorbidities and postoperative complications.

RESULTS

The mean follow-up was 5.49 years. The median time to BCVA postoperatively was 6 months, with 47% of patients achieving their BCVA by 3 months. The mean best achieved logMAR visual acuity was 0.71, representing a gain of 6 lines on the Snellen visual acuity chart. Postoperative glaucoma, retroprosthetic membrane (RPM) and endophthalmitis prolonged this duration. We found no correlation between the following factors and time to BCVA: gender, age, indication for KPro surgery, primary versus secondary KPro, number of previous penetrating keratoplasties, previous retinal surgery, intraoperative anterior vitrectomy and preoperative glaucoma.

CONCLUSION

In our retrospective cohort, the majority of subjects reached their BCVA between 3 and 6 months after KPro implantation. This duration was significantly prolonged by the development of postoperative glaucoma, RPM and endophthalmitis.

Mid-term prognosis of type I Boston keratoprosthesis reimplantation

Aim

To examine the mid-term visual and anatomical prognosis of patients who require reimplantation of a second Boston keratoprosthesis type 1 (B-KPro).

Methods

Retrospective observational case series of 122 patients (141 eyes) who received a B-KPro at a single institution were reviewed. Eyes that underwent a second B-KPro were included in the study. Primary endpoints were B-KPro retention, final visual acuity 20/200 and loss of light perception. Secondary endpoints included the occurrence of postoperative complications.

Results

Seventeen eyes (12%) required a B-KPro reimplantation. Corneal melt was the most common indication for replacement (88%). Mean follow-up time after the second B-KPro was 4.4±2.1 years. The Kaplan-Meier analysis estimated the second B-KPro retention rate at 79% over 8 years. Retroprosthetic membrane (RPM, 53%) was the most common complication. Forty-one per cent of the eyes suffered from corneal melt following their second B-KPro. One year after the second B-KPro, 47% of the patients retained a vision 20/200. Seven eyes (41.2%) lost light perception, which was secondary to an inoperable retinal detachment in five cases. Four eyes (24%) developed phthisis following inoperable retinal detachment (n=3) or endophthalmitis (n=1).

Conclusion

B-KPro reimplantation is a potentially sight- and globe-saving procedure for eyes with B-KPro failure, but the prognosis is guarded. B-KPro reimplantation can salvage ambulatory vision in a third of patients while another third of patients progress to loss of light perception. RPM and retinal detachment were important obstacles to visual rehabilitation while recurrent corneal melt was responsible for most cases of anatomical failure.

Comparison of the Clinical Efficacy of Boston Keratoprosthesis Type I and Repetitive Penetrating Keratoplasty for Refractory Keratopathy

OBJECTIVE

To compare the clinical efficacy of Boston Keratoprosthesis type I (B-KProI) and penetrating keratoplasty (PKP) for patients with refractory keratopathy after 1failed PKP in China.

METHOD

The 42 consecutive cases with refractory keratopathy after 1 failed PKP, from July 2010 to December 2014, were divided into 2 groups according to the surgical method: KPro group (n = 21) and PKP group (n = 21). Visual acuity (LogMAR), corneal graft transparency, postoperative complications and corneal graft survival rate were observed. The follow-up time was 2 years. The Kaplan-Meier curve was used to analyze the survival rate of the two groups of corneal grafts.

RESULTS

The average best corrected visual acuity (BCVA) at 1, 6, 12, 18, and 24 months in KPro group were significantly lower than PKP group (P < 0.01). The best postoperative visual acuity and BCVA at postoperative 2 years in KPro group were lower than PKP group. The success rate of KPro group (86%) were significantly higher than PKP group (43%) (P < 0.01). There were no significant differences in indicate of complications in 2 groups including secondary glaucoma, secondary infectious corneal ulcer, corneal graft melting and endophthalmitis (P > 0.05).

CONCLUSION

Compared with repetitive PKP, B-KProI had a higher success rate, improved postoperative visual acuity, reduced postoperative corneal transplant rejection rates and improved corneal graft survival rate.

Boston Type 1 Keratoprosthesis: Updated Perspectives

The use of Boston type 1 keratoprosthesis (BKPro) has significantly increased worldwide. It is no longer considered a procedure of last resort but a reasonable option for patients with otherwise poor prognosis for a traditional penetrating keratoplasty. BKPro was approved by the Food and Drug Administration in 1992 for bilateral severe corneal blindness due to multiple corneal transplant failure. Over the years, indications have extended beyond recurrent immunologic rejection to include other conditions such as chemical injury and other causes of bilateral limbal stem cell deficiency, extensive corneal neovascularization, neurotrophic corneas and hypotony, among others. Numerous advances in the design of the BKPro, improvement of preoperative, intraoperative and postoperative management have resulted in favorable outcomes and a reduction in postoperative complications. Accordingly, many studies have shown that implantation of this device is highly effective in restoring vision with very good short-term outcomes. However, due to the lifetime risk of sight-threatening complications after BKPro implantation, a longer follow-up period should provide outcomes that are more realistic. In this review, the authors examined only the results of publications with an average of at least 2 years of follow-up. The overall intermediate to long-term visual outcomes and retention rate in BKPro seem to be favorable. However, autoimmune diseases and cicatrizing conditions continue to show a higher incidence of postoperative complications that require further management.

Corneal graft melting: a systematic review

Corneal graft melting is a severe complication of keratoplasty. This review is to summarize the incidence, the pathogenesis, the risk factors, the prognosis and the prevention of corneal graft melting after keratoplasty. We systematically searched PubMed, Web of Science and WanFang database to retrieve potentially eligible articles about relevant clinical reports and animal experiments. We read the full texts to identify eligible articles. The selection of studies and data extraction were performed independently by two reviewers. In conclusion, the pathogenesis of corneal graft melting is complicated, and many risk factors are closely related to corneal graft melting. Analysis of pathogenesis and risk factors of corneal graft melting can facilitate the development of targeted therapies to better guide clinical practice.

[Boston Keratoprosthesis with temporal aponeurosis graft: A solution when there seems to be no more]

PURPOSE

To report cases of patients with severe bilateral corneal blindness and recurrent refractory perforation to keratoplasty and conventional treatment, for whom Boston keratoprosthesis (KP) was a satisfactory alternative when combined with a temporalis aponeurosis graft.

DESCRIPTION OF CASES

The first patient had progressive Lyell syndrome with spontaneous corneal perforation. The second had a severe graft vs. host reaction with a persistent Seidel-positive descemetocele. Despite repeated penetrating keratoplasties, amniotic membrane (AM) transplantations, and buccal mucosal (BM) grafts, they both experienced recurrent corneal perforation. The only solution thus appeared to be Boston Type I KP surgery. One month postoperatively, the first patient had to receive a temporalis aponeurosis (TA) graft, due to thinning of the recipient graft. Six months postoperatively, his visual acuity (VA) was 1/10 without correction, and the corneal status had been stabilized. The second patient underwent KP and TA graft concurrently. Six months after surgery, VA was 2/10 uncorrected, and the local inflammation had been stabilized.

OBSERVATION

Boston type I keratoprostheses constitute an alternative in cases of severe bilateral corneal blindness with perforation refractory to conventional treatment and surgery, with satisfactory visual results.

DISCUSSION

Patients with preoperative severe ocular surface disease are at greater risk of postoperative keratolysis. For our patients with a higher risk, TA graft prevented corneal melt. TA seems to be more effective than AM or BM in preventing corneal thinning or melt.

CONCLUSION

We would recommend performing a TA graft in combination with Boston KP surgery concurrently as first line treatment in eyes with severe ocular surface inflammation.

Keratoprostheses in silicone oil-filled eyes: long-term outcomes

PURPOSE

To analyse the functional and anatomical outcomes of different types of keratoprostheses in eyes with retained silicone oil following vitreoretinal surgery.

METHODS

Retrospective chart review of patients operated with any type of permanent keratoprosthesis (Kpro) in silicone oil-filled eyes between March 2003 and June 2017 were analysed.

RESULTS

40 silicone oil-filled eyes underwent keratoprostheses, of which 22 were type 1 and 18 were type 2 Kpros (Lucia variant-nine, modified osteo odonto kerato prosthesis (MOOKP)-four, Boston type 2-three and osteoKpro-two) with a mean follow-up of 61.54 , 42.77, 45.25 , 25 and 37 months, respectively. Anatomic retention of the primary Kpro was noted in 33 eyes (82.5%). A best-corrected visual acuity of better than 20/200 and 20/400 was achieved in 26 (65%)+32 (80%) eyes. Retroprosthetic membrane (RPM) was the most common complication noted in 17 eyes (42.5%). Perioptic graft melt was noted in 4 of 22 eyes of the type 1 Kpro (2 (10.5%) without associated ocular surface disorder (OSD)) and in 1 eye each of Boston and Lucia type 2 Kpro. Laminar resorption occurred in one eye each of the MOOKP and OKP groups. Endophthalmitis and glaucoma did not occur in any eye.

CONCLUSION

Appropriately chosen keratoprosthesis is a viable option for visual rehabilitation in eyes post vitreoretinal surgery with retained silicone oil-induced keratopathy not amenable to conventional penetrating keratoplasty. Kpro melt among type 1 Kpro did not occur in 89.5% eyes without associated OSD (19 of 22 eyes), despite the lack of aqueous humour and presence of RPM (4 eyes), two factors considered to play a significant role in the causation of sterile melts. Of interest to note was the absence of infection in any of these eyes. The possible protective role of oil from endophthalmitis is interesting, though yet to be ascertained.

Keratoprosthesis: Current global scenario and a broad Indian perspective

Keratoprosthesis (Kpro) forms the last resort for bilateral end-stage corneal blindness. The Boston Type 1 and 2 Kpros, the modified osteo-odonto Kpro and the osteo-Kpro are the more frequently and commonly performed Kpros, and this review attempts to compile the current data available on these Kpros worldwide from large single-center studies and compare the indications and outcomes with Kpros in the Indian scenario. Although the indications have significantly expanded over the years and the complications have reduced with modifications in design and postoperative regimen, these are procedures that require an exclusive setup, and a commitment toward long-term follow-up and post-Kpro care. The last decade has seen a surge in the number of Kpro procedures performed worldwide as well as in India. There is a growing need in our country among ophthalmologists to be aware of the indications for Kpro to facilitate appropriate referral as well as of the procedure to enable basic evaluation during follow-ups in case the need arises, and among corneal specialists interested to pursue the field of Kpros in understanding the nuances of these surgeries and to make a judicious decision regarding patient and Kpro selection and more importantly deferral.

Boston keratoprosthesis type 1: outcomes of the first 38 cases performed at Moorfields Eye Hospital

PURPOSE

To evaluate outcomes of Boston keratoprosthesis type 1 (K-Pro) surgery in a cohort of high-risk patients at Moorfields Eye Hospital. Our patients were referred to us at the end-point of their ocular disease.

METHODS

A retrospective review of all K-Pro surgery performed between March 2011 and July 2015 with a minimum follow-up of 12 months.

RESULTS

39 eyes of 38 patients were included. Mean follow-up was 28.4 months (range: 12-56). The main indication for surgery was bullous keratopathy from multiple failed grafts (56%). 26 cases (72.2%) had known posterior segment disease pre-operatively. Mean BCVA for the entire cohort (n = 39) initially improved from HM vision to 1/60 before returning to CF vision by 6 months and was maintained for the duration of follow-up. By final follow-up (n = 39), 46% had improved vision (1 line improvement in 10%; 2 lines or more in 36%) and 31% maintained pre-operative visual acuity. Anterior segment pathology was not an independent variable in visual outcome. However, absence of posterior segment disease was significant and performed best, improving from HM to 6/15 and maintaining that vision in the longer term. There were 13 (33%) cases of progressive glaucomatous optic neuropathy, 10 (26%) retinal detachments, 8 (21%) retroprosthetic membranes, 3 (8%) infective keratitis and 2 (5%) vitritis of which 1 progressed to endophthalmitis. In all, 3 (8%) had NPL vision and 4 (10%) required removal of the K-Pro.

CONCLUSIONS

Implantation of the Boston K-Pro can lead to improved vision, with the main limiting factor being posterior segment pathology.

No Light Perception Outcomes Following Boston Keratoprosthesis Type 1 Surgery

PURPOSE

To determine the incidence rate, principal causes, and clinical course of eyes developing no light perception (NLP) visual acuity (VA) following Boston Keratoprosthesis (B-KPro) type 1 surgery. Secondary objectives include determining the incidence rate, relative risk (RR), and survival probability with respect to NLP outcomes among eyes with congenital aniridia.

DESIGN

Retrospective, interventional case series.

SUBJECTS

All patients undergoing B-KPro type 1 surgery between October 2008 and June 2016 by a single surgeon at CHUM - Hôpital Notre-Dame.

METHODS

Records of patients having undergone B-KPro implantation were reviewed. Eyes with a final outcome of NLP were further reviewed to determine best recorded postoperative VA, time to NLP onset, clinical course, and principal cause. Descriptive statistics, incidence rates, Kaplan-Meier survival curves, and the RR of NLP outcomes among eyes with aniridia were determined. Statistical significance was defined as P < .05.

RESULTS

Records of 119 patients were included, with an average follow-up of 49.1 ± 26.8 months postoperatively. Nineteen eyes had a final outcome of NLP, representing 16.0%. The incidence rate of NLP was 0.04 cases per eye-year of follow-up. The most common principal causes were inoperable retinal detachment (n = 7, 36.8%), terminal glaucoma (n = 6, 31.6%), and carrier graft melt-related complications (n = 5, 26.3%). The RR of developing NLP among eyes with aniridia was 3.04 (P = .01).

CONCLUSIONS

No light perception is a devastating but uncommon outcome of B-KPro surgery. Patients with aniridia seem to be at increased risk. In spite of all available medical and surgical interventions, some eyes may still suffer this outcome.

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

PURPOSE

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.