Endoscopic-Assisted Vitrectomy for Corneal Transplant Complications

(KPro-HP-Endo Trial)

Not currently recruiting at 1 trial location

Overseen By Marie-Catherine Tessier, M.Sc.

Age: 18+

Sex: Any

Trial Phase: Academic

Sponsor: Centre hospitalier de l'Université de Montréal (CHUM)

Disqualifiers: Repeat keratoprosthesis, Repeat vitrectomy, others

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Approved in 2 Jurisdictions This treatment is already approved in other countries

Compensation: Varies

Number of Visits: 1

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial aims to improve outcomes for individuals undergoing a specific corneal transplant known as the Boston keratoprosthesis. Researchers are testing whether using a tiny camera (endoscopy) to assist in vitrectomy (removal of the eye's vitreous gel) can reduce common complications such as membrane formation behind the implant, glaucoma, and retina issues. The trial is suitable for candidates of both the Boston keratoprosthesis and vitrectomy surgeries. As an unphased trial, it offers patients the chance to contribute to innovative research that could enhance surgical outcomes and reduce complications.

Do I have to stop taking my current medications for this trial?

The trial protocol does not specify whether you need to stop taking your current medications.

What prior data suggests that this endoscopic-assisted vitrectomy is safe for corneal transplant complications?

Research has shown that the Boston keratoprosthesis type 1 (KPro) surgery can lead to complications such as the formation of a retroprosthetic membrane (a layer that forms behind the implant), glaucoma (a condition that can damage vision), and retinal detachment (when the retina pulls away from the back of the eye). Despite these risks, the Boston KPro can improve vision in individuals who might otherwise face a poor outlook.

To enhance safety, using a small camera called an endoscope during surgery might help. It can facilitate the removal of the anterior hyaloid membrane, a part of the eye involved in these complications. This step is challenging due to limited visibility during the procedure. The endoscope might reduce the likelihood of these issues occurring post-surgery. However, detailed data from clinical trials is still limited to fully confirm this.

Overall, while known risks exist, using endoscopy in these procedures is thought to potentially lower the risk of complications from the surgery. ^{1 2 3 4 5}

Why are researchers excited about this trial?

Researchers are excited about the endoscopic-assisted vitrectomy technique for addressing corneal transplant complications because it brings a fresh approach to treating these issues. Unlike standard treatments that typically don't integrate advanced visualization techniques, this method uses endoscopy to assist with anterior hyaloid membrane peeling, offering a more precise view of the eye's interior. This enhanced visualization allows for more accurate and effective surgical interventions. Moreover, the combination with Boston keratoprosthesis type 1 could potentially improve outcomes by addressing both the front and back of the eye simultaneously, which is not typically possible with traditional methods.

What evidence suggests that endoscopic-assisted vitrectomy is effective for reducing complications in corneal transplant surgery?

Research has shown that using a Boston keratoprosthesis type 1 (KPro) with endoscopic-assisted vitrectomy can help prevent complications after corneal surgery. In this trial, patients will receive a Boston keratoprosthesis type 1 (KPro) with a pars plana vitrectomy (PPV) and anterior hyaloid membrane peeling, assisted by endoscopy. Studies have found that patients undergoing a complete vitrectomy, which involves removing a thin layer in the eye, experience fewer issues such as membrane formation and vision loss due to glaucoma. Endoscopy enhances the surgeon's visibility during the procedure, increasing its effectiveness. Overall, KPro treatments have been successful in maintaining device placement and improving vision. This combined approach aims to enhance outcomes by reducing common issues that can occur after KPro surgery. ^{2 6 7 8 9}

Who Is on the Research Team?

Mona Harissi-Dagher, MD, FRCSC

Principal Investigator

Centre hospitalier de l'Université de Montréal (CHUM)

Are You a Good Fit for This Trial?

This trial is for adults aged 18 to 80 who are candidates for a corneal transplant using the Boston keratoprosthesis type 1 and also need vitrectomy surgery. Participants must be able to follow the study's procedures over time. It's not open to those under 18 or over 80, anyone unable to consent, or patients needing repeat surgeries of these types.

Inclusion Criteria

I am a candidate for eye surgery to remove the vitreous gel.

Informed consent

Boston keratoprosthesis candidate

Exclusion Criteria

I am unable to understand and agree to the study's details.

Repeat Boston keratoprosthesis

I have had more than one vitrectomy surgery.

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Surgery and Treatment

Participants undergo Boston keratoprosthesis type 1 (KPro) surgery with pars plana vitrectomy (PPV) and anterior hyaloid membrane peeling assisted by endoscopy

1 day

1 visit (in-person)

Follow-up

Participants are monitored for postoperative complications such as glaucoma, retroprosthetic membrane formation, and retinal detachment

12 months

Regular visits (in-person)

What Are the Treatments Tested in This Trial?

Interventions

• Boston keratoprosthesis type 1 and anterior hyaloid membrane peeling assisted by endoscopy

Trial Overview The study tests if peeling the anterior hyaloid membrane with endoscopic assistance during corneal transplant surgery can reduce complications like glaucoma and retinal detachment compared to doing this step after the transplant without endoscopy.

How Is the Trial Designed?

Group I: Patients with KPro, PPV, and endoscopy Experimental Treatment 1 Intervention

Patients will receive at the same time a Boston keratoprosthesis type 1 (KPro) with a pars plana vitrectomy (PPV) with anterior hyaloid membrane peeling assisted by endoscopy.

Boston keratoprosthesis type 1 and anterior hyaloid membrane peeling assisted by endoscopy is already approved in United States, European Union for the following indications:

Approved in United States as Boston Type 1 Keratoprosthesis for:

• Severe corneal opacity
• Multiple graft failures
• Stevens-Johnson syndrome
• Ocular cicatricial pemphigoid
• Aniridia
• Chemical injury
• Corneal blindness

Approved in European Union as Boston Type 1 Keratoprosthesis for:

• Severe corneal opacity
• Multiple graft failures
• Stevens-Johnson syndrome
• Ocular cicatricial pemphigoid
• Aniridia
• Chemical injury
• Corneal blindness

Who Is Running the Clinical Trial?

Centre hospitalier de l'Université de Montréal (CHUM)

Lead Sponsor

Trials

389

Recruited

143,000+

Published Research Related to This Trial

The Boston Keratoprosthesis (KPro) can be successfully implanted using an ipsilateral failed corneal graft as the support tissue, addressing the issue of donor tissue scarcity.

This innovative approach allows for the use of the patient's own corneal tissue, potentially improving outcomes in patients who require both vitrectomy and KPro implantation.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

A failed corneal graft as a support for the Boston Keratoprosthesis type 1. Kyrillos, R., Harissi-Dagher, M.[2021]

A new technique allows for the complete replacement of the donor corneal carrier in type 1 Boston keratoprosthesis (KPro) without damaging the existing hardware, which can help preserve the functionality of the KPro.

This method was successfully applied in two cases of sterile corneal melts, demonstrating that it is possible to salvage the KPro by selectively replacing the corneal carrier, thus avoiding the need for a full KPro disassembly.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

A Technique to Rescue Keratoprosthesis Melts. Feng, MT., Burkhart, ZN., McKee, Y., et al.[2015]

In a study of 43 eyes from 37 patients followed for an average of 39 months, the type I Boston keratoprosthesis (KPro) significantly improved vision, with 77% of eyes achieving a visual acuity of 20/200 or better after one year.

Despite its effectiveness in restoring vision, the procedure is associated with notable complications, including retroprosthetic membrane formation in 51% of cases and glaucoma progression in 47%, highlighting the need for careful monitoring post-surgery.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Primary implantation of type I Boston keratoprosthesis in nonautoimmune corneal diseases. Chang, HY., Luo, ZK., Chodosh, J., et al.[2022]

The Boston keratoprosthesis (BI-KPro) has been successfully implanted in 24 eyes at the University of Cologne and 28 eyes at the University of Salzburg, resulting in a significant visual acuity improvement in 96% of cases in Cologne and 62% in Salzburg.

Despite a high complication rate of 81% in Salzburg, the BI-KPro remains the most commonly used artificial corneal replacement for high-risk eyes, indicating its efficacy in improving vision even in challenging cases.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

[Mid- and Longterm Experiences with the Boston-Keratoprosthesis. The Cologne and Salzburg Perspective]. Schaub, F., Bachmann, BO., Seyeddain, O., et al.[2018]

The Boston Keratoprosthesis (KPro) has seen significant design improvements and treatment strategies that enhance its effectiveness for patients with severe corneal diseases, making it a viable primary surgical option for those with poor prospects for traditional corneal transplants.

Outcomes such as visual acuity, retention of the implant, and rates of post-operative infections have all improved, providing patients with better opportunities for visual rehabilitation, especially in regions facing donor cornea shortages.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

[The Boston keratoprosthesis]. Wang, L., Huang, Y., James, C., et al.[2014]

In a study of 23 small-gauge vitreoretinal surgeries performed on 14 eyes with Boston Type 1 keratoprosthesis, modern techniques like sutureless vitrectomy were successfully utilized, achieving anatomical goals without serious complications.

Performing vitrectomy during the placement of the keratoprosthesis reduced the formation of retro-KPro membranes and improved visual acuity in most cases, despite preexisting conditions.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Vitreoretinal surgery in the setting of permanent keratoprosthesis. Kiang, L., Sippel, KC., Starr, CE., et al.[2015]

The Boston type 1 keratoprosthesis (KPro) shows promising short-term results, with 62% of patients achieving at least 6/60 vision at 2 years, but this drops to 51% at 5 years, indicating a decline in visual outcomes over time.

The device retention rate is high at 88% after 2 years but decreases to 74% by 5 years, and common complications such as retroprosthetic membrane and glaucoma highlight the need for careful patient selection and ongoing monitoring.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Systematic Review and Meta-Analysis of the Medium- and Long-Term Outcomes of the Boston Type 1 Keratoprosthesis. Priddy, J., Bardan, AS., Tawfik, HS., et al.[2020]

In a study of 41 eyes from 37 patients who underwent Boston type 1 keratoprosthesis (KPro1) implantation, most patients experienced significant improvement in visual acuity, with the mean best corrected visual acuity improving from 2.05 to 1.16 logMAR after surgery.

Despite the overall positive visual outcomes, patients with a history of multiple ocular surgeries or systemic immune disorders faced higher risks of serious complications, including retroprosthetic membrane formation and infections, highlighting the need for careful patient selection.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Post-surgical visual outcome and complications in Boston type 1 keratoprosthesis. Muñoz-Gutierrez, G., Alvarez de Toledo, J., Barraquer, RI., et al.[2013]

The Boston type I keratoprosthesis (BI-KPro) significantly improves vision in patients with severe corneal opacification, with 45% to 89% of eyes achieving a best-corrected visual acuity of 20/200 or better, based on a review of 22 relevant studies.

While the BI-KPro shows promise, it is associated with serious complications such as retroprosthetic membrane formation and elevated intraocular pressure, highlighting the need for careful monitoring after surgery.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Boston Keratoprosthesis: Outcomes and Complications: A Report by the American Academy of Ophthalmology. Lee, WB., Shtein, RM., Kaufman, SC., et al.[2019]

The incidence of traumatic wound rupture in patients with Boston type 1 keratoprosthesis is 2.9%, occurring on average 4.2 months after surgery, primarily at the graft-host junction.

Outcomes after traumatic rupture vary; while some patients experienced significant vision loss, others maintained or improved their vision after treatment, highlighting the importance of protective measures to prevent such complications.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Traumatic wound rupture after Boston type 1 keratoprosthesis implantation. Ang, AY., Chan, CC., Nordlund, ML., et al.[2016]

Citations

1. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC4601904/

Donor Corneal Transplantation vs Boston Type 1 ... Forty-seven percent of PK eyes vs 40% of KPro eyes were able to retain this visual acuity. Two-year rate of failure to retain visual acuity better than the ...

2. sciencedirect.com sciencedirect.com/science/article/pii/S0002939421003159

Long-term Outcomes of Boston Type I Keratoprosthesis ... Twenty-seven eyes of 26 patients were recruited. The most common indication for KPro surgery was failed penetrating keratoplasties (22 eyes, 81.5%).

3. aaojournal.org aaojournal.org/article/s0161-6420(15)00306-1/fulltext

Boston Keratoprosthesis: Outcomes and Complications 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 ...

4. pubmed.ncbi.nlm.nih.gov pubmed.ncbi.nlm.nih.gov/19724214/

Boston keratoprosthesis outcomes and complications Retention rates were excellent, and best-corrected visual acuities improved in the vast majority of patients. Complications can occur and require frequent ...

5. sciencedirect.com sciencedirect.com/science/article/abs/pii/S1542012420301191

Predictive factors of Boston Type I Keratoprosthesis ... Our study showed a high probability of KPro device retention at 10 years (89.2%), although in some cases the initial device failed.

6. withpower.com withpower.com/trial/phase-ocular-hypertension-3-2020-090ed

Endoscopic-Assisted Vitrectomy for Corneal Transplant ... Common complications of the Boston keratoprosthesis type 1 (KPro) surgery include retroprosthetic membrane formation, glaucoma, and retinal detachment.

7. canadianjournalofophthalmology.ca canadianjournalofophthalmology.ca/article/S0008-4182(23)00166-7/abstract

Review of clinical trials addressing the Boston ... There are few clinical trials published and underway on the Boston KPro, and none directly compare KPro outcomes with repeat corneal transplantation.

8. aging.networkofcare.org aging.networkofcare.org/sanmateo/CommunityResources/ClinicalTrials/Detail/NCT04337944?keyword=%22Vitrectomy%22

Endoscopic Assisted Anterior Hyaloid Peeling in Boston ... Common complications of KPro surgery include retroprosthetic membrane formation behind the backplate of the KPro. Glaucoma is the most common threat to vision ...

9. researchgate.net researchgate.net/publication/371117868_Review_of_clinical_trials_addressing_the_Boston_Keratoprosthesis

Review of clinical trials addressing the Boston ... Indication for KPro was reported in 67% of trials (4 of 6), with primary KPro accounting for 22% of unique eyes (13 of 58) and KPro after corneal graft failure ...