Prospective studies of minimally invasive glaucoma surgeries: Systematic review and quality assessment

Authors: Rosdahl JA, Gupta D.

Geographical coverage: Not reported

Sector: Glaucoma

Sub–sector: Treatment

Equity focus: Not reported

Study population: Patients with open-angle glaucoma

Review type: Effectiveness review

Quantitative synthesis method: Narrative synthesis

Qualitative synthesis method: Not applicable

Background

Traditional treatments for glaucoma include topical and oral anti‑ocular hypertensive medications, glaucoma lasers and incisional surgery such as trabeculectomy. Recently, several new surgical procedures collectively termed micro‑invasive glaucoma surgery (MIGS) have gained popularity. Many of these procedures offer a better safety profile than traditional incisional surgery, and there is hope that they will prove more effective than topical anti‑hypertensives. However, because these procedures are relatively new, their long‑term safety and efficacy remain under investigation.

Objectives 

To critically appraise prospective studies of MIGS with respect to study design, length of follow‑up, funding sources and potential author conflicts of interest.

Main findings 

Overall, MIGS appears to provide safe and effective glaucoma management. The search identified 1 015 records, of which 87 studies met the inclusion criteria. Only 22 studies (25 %) were registered in a national clinical‑trials database. Study durations were generally short, with only 30 % lasting two years or more. Most studies (74 %) lacked a control group and relied on baseline comparisons. More than half (53 %) were industry funded. Twelve of the highest‑quality studies were reviewed in detail. MIGS procedures consistently lowered intra‑ocular pressure (IOP) and reduced dependence on glaucoma medications. Complication rates were generally lower than those reported for traditional surgery.

Procedures such as the iStent, Trabectome and Xen gel stent were the most frequently studied. Endoscopic cyclophotocoagulation (ECP), MicroPulse laser trabeculoplasty and ab‑interno trabeculotomy showed comparable or improved outcomes relative to traditional treatments, with fewer complications. Devices such as the Hydrus Microstent and the now‑withdrawn CyPass micro‑stent produced substantial IOP reductions when combined with cataract surgery.

Methodology

A literature search of PubMed was conducted on 14 November 2018 to identify English‑language prospective studies that reported MIGS outcomes in adults with open‑angle glaucoma. Reference lists of relevant reviews were scanned for additional publications.

Initial title and abstract screening was conducted by one reviewer. Two reviewers then independently assessed full‑text articles and resolved disagreements by discussion. Study quality was evaluated independently by two reviewers, and findings were synthesised narratively.

Applicability / external validity

The included studies were limited by small sample sizes and a restricted spectrum of glaucomatous disease. The review notes that high‑quality comparative studies of MIGS are needed to inform treatment decisions.

Geographic focus 

The location of included studies was not reported by the review authors.

Summary of quality assessment 

Confidence in the review’s conclusions is low owing to an incomplete search strategy (single database, English‑language only), lack of contact with study authors or topic experts, and the absence of an excluded‑studies list. The number of reviewers involved in data extraction was not specified.