Endoscopic-Assisted Vitrectomy for Corneal Transplant Complications

(KPro-HP-Endo Trial)

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

20 Participants Needed

Trial Summary

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 data supports the idea that Endoscopic-Assisted Vitrectomy for Corneal Transplant Complications is an effective treatment?

The available research shows that the Boston keratoprosthesis, which is used in Endoscopic-Assisted Vitrectomy for Corneal Transplant Complications, has improved outcomes for patients. Specifically, it has led to better visual acuity, meaning patients can see more clearly after the procedure. Additionally, the rates of keeping the implant in place and reducing post-operative infections have significantly improved. This makes it a strong alternative for patients who have a poor outlook with traditional corneal transplants. ^{1 2 3 4 5}

What safety data exists for endoscopic-assisted vitrectomy in corneal transplant complications?

The safety data for the Boston type 1 keratoprosthesis (KPro), which is related to endoscopic-assisted vitrectomy for corneal transplant complications, includes several studies. The American Academy of Ophthalmology reviewed outcomes and complications of the Boston KPro for corneal opacification. A systematic review and meta-analysis evaluated medium- to long-term safety, focusing on visual outcomes, device retention, and postoperative complications. Other studies reported on visual outcomes and serious post-operative complications, as well as specific issues like traumatic wound rupture. These studies provide insights into the safety and complications associated with the Boston KPro, which may be relevant to the treatment in question. ^{3 4 5 6 7}

Is the Boston keratoprosthesis type 1 and anterior hyaloid membrane peeling assisted by endoscopy a promising treatment for corneal transplant complications?

Yes, the Boston keratoprosthesis type 1, also known as Boston KPro, is a promising treatment for corneal transplant complications. It is widely used for patients with severe corneal issues and has shown significant improvements in vision for most patients. The treatment has been enhanced over time, making it a reliable option for those who cannot undergo traditional corneal transplants. ^{1 4 8 9 10}

What is the purpose of this trial?

Common complications of the Boston keratoprosthesis type 1 (KPro) surgery include retroprosthetic membrane formation, glaucoma, and retinal detachment. Often pars plana vitrectomy (PPV) is performed at the same time as KPro surgery for different indications. It has been shown to reduce postoperative complications in comparison to when it is performed after the KPro surgery. Patients who receive a complete PPV with peeling of the anterior hyaloid membrane have a lower incidence of retroprosthetic membrane formation and less vision loss due to glaucoma when compared to patients with partial PPV or anterior vitrectomy. During a complete PPV, peeling of the anterior hyaloid membrane is a difficult step because visualisation is poor, but it can be improved using endoscopy. The investigators suggest that peeling of the anterior hyaloid membrane assisted by endoscopy during KPro surgery would decrease postoperative complications in comparison to a PPV done after KPro surgery and without endoscopy.

Research Team

Mona Harissi-Dagher, MD, FRCSC

Principal Investigator

Centre hospitalier de l'Université de Montréal (CHUM)

Eligibility Criteria

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

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)

Treatment Details

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.

Participant Groups

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+

Findings from Research

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]

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]

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 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]

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]

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 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]

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]

References

1. China pubmed.ncbi.nlm.nih.gov

[The Boston keratoprosthesis]. [2014]

2. United States pubmed.ncbi.nlm.nih.gov

A Technique to Rescue Keratoprosthesis Melts. [2015]

3. United States pubmed.ncbi.nlm.nih.gov

Primary implantation of type I Boston keratoprosthesis in nonautoimmune corneal diseases. [2022]

4. Spain pubmed.ncbi.nlm.nih.gov

Post-surgical visual outcome and complications in Boston type 1 keratoprosthesis. [2013]

5. United States pubmed.ncbi.nlm.nih.gov

Boston Keratoprosthesis: Outcomes and Complications: A Report by the American Academy of Ophthalmology. [2019]

6. United States pubmed.ncbi.nlm.nih.gov

Systematic Review and Meta-Analysis of the Medium- and Long-Term Outcomes of the Boston Type 1 Keratoprosthesis. [2020]

7. England pubmed.ncbi.nlm.nih.gov

Traumatic wound rupture after Boston type 1 keratoprosthesis implantation. [2016]

8. United States pubmed.ncbi.nlm.nih.gov

Vitreoretinal surgery in the setting of permanent keratoprosthesis. [2015]

9. United States pubmed.ncbi.nlm.nih.gov

A failed corneal graft as a support for the Boston Keratoprosthesis type 1. [2021]

10. Germany pubmed.ncbi.nlm.nih.gov

[Mid- and Longterm Experiences with the Boston-Keratoprosthesis. The Cologne and Salzburg Perspective]. [2018]