Graft Selection for Glaucoma Surgery
What You Need to Know Before You Apply
What is the purpose of this trial?
Glaucoma refers to a group of progressive optic neuropathies that lead to permanent vision loss. Glaucoma is the leading cause of irreversible blindness globally. In 2020, it was estimated to affect 76 million individuals worldwide, with projections indicating this number will rise to 111.8 million by 2040. In Canada, glaucoma affects an estimated 2.7-7.5% of individuals over the age of 50, contributing substantially to the national disease burden. This condition is linked to damage of the optic nerve due to elevated intraocular pressure (IOP; raised eye pressure), which results in the loss of retinal ganglion cells. Therefore, most of the treatments are guided towards reducing the IOP either via using laser, medications or surgery.
Glaucoma surgery is typically reserved for cases where IOP remains uncontrolled while on maximum tolerated medical therapy and/or where glaucoma progression warrants surgery. The goal of many glaucoma surgeries is to divert aqueous humor from the anterior chamber to the subconjunctival space, therefore reducing intraocular pressure. The device used for this purpose are the PRESERFLO™ MicroShunt (Glaukos Corporation, Laguna Hills, CA, USA) (we will interchangeably use terms "stent" and "shunt" to refer to these devices in the text below). The device is implanted using the ab externo approach to channel fluid from the anterior chamber to the subconjunctival/subtenon space. To reduce postoperative fibrosis and inhibit fibroblast activity that could obstruct flow and lead to device failure, 5-fluorouracil (5-FU) or mitomycin C (MMC) are administered. Additionally, a double-layered closure of conjunctiva and Tenon's is performed to minimize Tenon's migration and blockage of tenon the stents. Despite these measures, stent encapsulation and failure are still too common requiring revisions and bleb needling in 2-20% of cases within the first 12 months of follow-up.
This project will involve a series of studies evaluating graft selection in PreserFlo MicroShunt implantation, focusing on donor sclera, cornea, and pericardium as patch graft materials. First, we will conduct a prospective, randomized study comparing clinical outcomes between these graft types. Outcomes of interest will include surgical success rates, post-operative hypotony, tube erosion, conjunctival complications, infection, and overall device longevity. Donor sclera has long been used as a patch graft in glaucoma drainage device surgery and is associated with low erosion rates and reliable long-term results. Corneal tissue is increasingly used due to its transparency and availability through eye banks, with demonstrated safety in ocular surface reconstruction and tube coverage. Pericardium is another durable, biocompatible option, historically applied in both cardiovascular and ocular surgery, and has shown effectiveness as a patch graft in glaucoma drainage implants. This comparison will extend to both primary implantation and revision surgeries, recognizing the high clinical relevance of graft performance in complex cases.
Building on these results, we will then perform a cost-effectiveness analysis of graft strategies, incorporating surgical time, post-operative management, complication rates, and need for re-operation. An economic model will be developed to evaluate costs and resource utilization associated with each material, providing valuable data for policy and surgical decision-making. Finally, we will conduct a patient-reported outcome (PRO) study to assess patient comfort and satisfaction with different grafts. Surveys will evaluate domains such as foreign body sensation, cosmesis, and overall satisfaction at key time points (immediate post-operative period, 1 week, 3 weeks, and 3 months). These results will highlight the patient perspective, an often underrepresented but critical factor in surgical innovation.
Together, these studies will comprehensively assess graft selection from surgical, economic, and patient-centered perspectives, informing evidence-based practice in glaucoma care.
Are You a Good Fit for This Trial?
This trial is for individuals with glaucoma who need surgery because their eye pressure remains high despite maximum tolerated medical therapy or due to disease progression. Participants must be suitable candidates for the PRESERFLO™ MicroShunt implantation.Inclusion Criteria
Exclusion Criteria
What Are the Treatments Tested in This Trial?
Interventions
- MicroShunt with Corneal Patch Graft
- MicroShunt with Pericardial Patch Graft
- MicroShunt with Scleral Patch Graft
Trial Overview
The study tests three types of patch grafts used in glaucoma surgery: donor sclera, cornea, and pericardium. It aims to compare surgical success rates, complications like low eye pressure after surgery, tube erosion, conjunctival issues, infections, and device longevity.
How Is the Trial Designed?
3
Treatment groups
Experimental Treatment
Participants undergo PreserFlo MicroShunt implantation with a pericardial patch graft covering the tube. Standard perioperative care and identical follow-up schedule. Outcomes as above: IOP control, complication profile, reoperations, longevity, patient-reported outcomes, and resource use. Primary and revision cases are included per stratified randomization.
Participants undergo PreserFlo MicroShunt implantation with a donor scleral patch graft covering the tube. Standard perioperative care (e.g., MMC/5-FU per site protocol) and scheduled follow-up (day 1; week 1-2; months 1, 3, 6, 9, 12). Outcomes include IOP, hypotony, tube erosion, conjunctival complications, infection, reoperations, device longevity, patient-reported comfort/cosmesis, and resource use. Primary and revision cases are included per stratified randomization.
Participants undergo PreserFlo MicroShunt implantation with a donor corneal patch graft covering the tube. Standard perioperative care and identical follow-up schedule. Outcomes as above: IOP control, complications (including erosion and hypotony), reoperations, longevity, patient-reported outcomes, and resource use. Primary and revision cases are included per stratified randomization.
Find a Clinic Near You
Who Is Running the Clinical Trial?
University of Alberta
Lead Sponsor
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