Device‐modified trabeculectomy for glaucoma

Author: Park J, Rittiphairoj T, Wang X, E J‑Y, Bicket AK

Geographical coverage: North America, Europe, and Africa

Sector: Glaucoma

Sub–sector: Treatment

Equity focus: Not explicitly stated

Study population: Adult patients with glaucoma

Review type: Effectiveness review

Quantitative synthesis method: Meta-analysis

Qualitative synthesis method: Not applicable

Background

Glaucoma is a leading cause of irreversible blindness and is projected to affect more than 111.8 million people worldwide by 2040. The disease is characterised by progressive optic neuropathy in which elevated intraocular pressure (IOP) is the principal modifiable risk factor. Standard trabeculectomy remains the surgical gold standard for lowering IOP, yet its long‑term success can be hampered by hypotony, infection and subconjunctival scarring. Device‑modified procedures—including the Ex‑PRESS shunt, PreserFlo MicroShunt and XEN Gel Stent—aim to reduce these complications while maintaining effective pressure control; however, their comparative benefits and harms remain uncertain.

Objectives

To assess the benefits and harms of device‑modified trabeculectomy compared with standard trabeculectomy for the control of IOP in adults with glaucoma.

Main findings

The review included eight randomised controlled trials (n = 961) conducted in North America, Europe and Africa, with follow‑up ranging from 6 months to 5 years. Most trials were at low risk of reporting bias but at high risk of detection bias.

• Five studies (213 eyes) suggested that Ex‑PRESS combined with trabeculectomy may achieve a slightly lower mean IOP at 12 months than standard trabeculectomy (mean difference (MD) −1.76 mmHg; 95 % confidence interval (CI) −2.91 to −0.61).
• One study indicated that PreserFlo MicroShunt might lead to a higher IOP at 12 months than standard trabeculectomy (MD +3.20 mmHg; 95 % CI 0.92 to 5.48).
• Device‑modified surgery appears to lower the risk of postoperative hypotony or a shallow anterior chamber. In the largest trial of PreserFlo MicroShunt (526 eyes), the risk ratio (RR) was 0.44 (95 % CI 0.25 to 0.78) compared with standard trabeculectomy.
• Across all trials, device‑modified trabeculectomy was associated with fewer cataract surgeries during follow‑up (pooled RR 0.46; 95 % CI 0.26 to 0.83).

The certainty of these estimates was graded as low to moderate owing to imprecision and risk of detection bias.

Methodology

Searches of the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (including MEDLINE In‑Process and Daily), Embase, PubMed, Latin American and Caribbean Literature on Health Sciences (LILACS), the metaRegister of Controlled Trials, ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform (ICTRP) were undertaken from database inception to August 2021 without language or date restrictions. Two reviewers independently screened records, extracted data and assessed risk of bias using the Cochrane Risk of Bias tool. Certainty of the evidence was graded with the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach. Random‑effects meta‑analysis was performed; statistical heterogeneity was quantified with the I² statistic and results were summarised narratively when I² exceeded 50 %.

Applicability / external validity

The evidence arises from specialist centres in high‑ and middle‑income settings; results may not be generalisable to populations with different demographic profiles, glaucoma subtypes or access to postoperative care. Limited data were available for Black, Asian and other minoritised ethnic groups, and for eyes with prior intraocular surgery.

Geographic focus

Included studies were conducted in North America, Europe and Africa.

Summary of quality assessment

Although systematic methods were used and the body of evidence is based on randomised trials, limitations in masking, outcome assessment and imprecision lower confidence in the effect estimates. Overall, the certainty of evidence is considered moderate for intraocular pressure outcomes and low for most safety outcomes.