Comparing the safety and efficacy of Preserflo Microshunt implantation and trabeculectomy for glaucoma: A systematic review and meta-analysis

Author: Khan A, Khan AU

Geographical coverage: Germany, UK, US, France, Italy, Holand, and Spain.

Sector: Glaucoma teratment

Sub–sector: Safety and efficacy

Equity focus: Not explicitly stated

Study population: 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. About 80 million people were affected worldwide in 2024, and the figure is projected to rise to 111.8 million by 2040. The most common form, primary open‑angle glaucoma (POAG), progresses silently and irreversibly, so current surgical and medical approaches aim to lower intra‑ocular pressure (IOP) to slow the disease. Trabeculectomy has long been the gold‑standard surgical procedure, especially for severe or rapidly progressive cases that are refractory to medication. However, short‑ and long‑term complications have prompted the development of minimally invasive glaucoma surgery (MIGS). The Preserflo MicroShunt, a flexible, biocompatible implant that creates a controlled aqueous outflow pathway, is one such MIGS option. It is designed to lower IOP while reducing complications such as hypotony, bleb‑related infection and fibrosis. Both the Preserflo MicroShunt and trabeculectomy have shown efficacy, acceptable safety and durability.

Objectives

To compare the safety and efficacy of the Preserflo MicroShunt with trabeculectomy for the surgical management of glaucoma.

Main findings

Seven studies (one randomised controlled trial and six observational cohorts) involving 1 353 eyes met the inclusion criteria (Preserflo MicroShunt, n = 812; trabeculectomy, n = 541). The mean follow‑up was 12.8 months.

• Effectiveness: Trabeculectomy achieved a significantly lower postoperative IOP (mean difference [MD] = 0.78 mm Hg; 95 % confidence interval [CI] 0.66 to 0.90; p < 0.001) and a greater absolute IOP reduction (MD = –1.20 mm Hg; 95 % CI –2.30 to –0.09; p = 0.034). It also resulted in a larger reduction in glaucoma medications (MD = –0.32; 95 % CI –0.58 to –0.07; p = 0.014).
• Safety: No statistically significant differences were detected between groups for hypotony, choroidal effusion, hyphaema or a flat anterior chamber. Trabeculectomy was associated with a higher incidence of bleb‑related complications and a greater need for re‑intervention. Preserflo procedures were, on average, quicker (mean 54 minutes vs 73 minutes) and required fewer postoperative visits (mean 9.85 vs 14.25).

Methodology

The authors searched PubMed, Embase, MEDLINE, Web of Science and reference lists up to 21 June 2023 with no language restrictions. Eligible studies included adults undergoing Preserflo MicroShunt implantation or trabeculectomy with a minimum six‑month follow‑up and reported postoperative IOP, glaucoma medication use or complications. Two reviewers independently screened articles, extracted data and evaluated methodological quality with the Newcastle–Ottawa Scale. Heterogeneity was quantified with I²; fixed‑ or random‑effects models were applied accordingly, and publication bias was explored with Begg’s and Egger’s tests.

Applicability/external validity

Most included studies were non‑randomised, raising concerns about selection bias and confounding. Small sample sizes and short follow‑up limit insight into long‑term efficacy and safety. The findings therefore apply principally to the first postoperative year in similar high‑income settings and should be interpreted with caution for other populations.

Geographic focus

The included studies were conducted in Germany, the UK, the USA, France, Italy, the Netherlands and Spain.

Summary of quality assessment

We have low to moderate confidence in the review’s conclusions. Although the search strategy was comprehensive and study quality was appraised, only one randomised controlled trial was available and the remainder were observational. The authors did not report using a second reviewer for data extraction or provide a list of excluded studies, and key confounders were not consistently adjusted for across studies. These limitations weaken the certainty of the pooled estimates.