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Taking people in Hong KongPhase 2

Tests metformin to protect the optic nerve in glaucoma

Tests metformin, a diabetes drug, against placebo in adults with glaucoma.

Key facts

Who runs it
Christopher Kai Shun Leung
Where
Wong Chuk Hang, Hong KongSee the site
Trial code
Registry title
Metformin as a Neuroprotective Therapy for Glaucoma
Status
Recruiting
Phase
Phase 2
People taking part
125 people, planned
Started
1 Jun 2025
Expected to end
31 Dec 2027
Type of study
Interventional, 2 groupsOne group gets an existing treatment, for comparison.
Treatments tested
  • Metformin
  • Placebo
Record updated
20 November 2025

Who can take part

AI summary

From the trial's eligibility criteria. Machine-read from the registry text on this page, so it can be wrong. The registry text below and the trial team decide who can take part.

The trial is looking for adults with primary open angle glaucoma whose optic nerve layers are getting thinner over time. It tests metformin against placebo.

Age
18 years or older.
Sex
All sexes can join.
Disease stage
Glaucoma with progressive thinning of the retinal nerve fiber layer and/or ganglion cell inner plexiform layer in at least one eye over the past 3 years, shown by OCT progression analysis.
Biomarker or test result
Eye pressure of 24mmHg or lower at the screening and baseline visits. Best corrected visual acuity of 20/40 or better.

Main reasons for not taking part

  • Diabetes, kidney disease or liver disease
  • Pathological myopia
  • Cognitive impairment, such as Alzheimer's disease
  • Other diseases that can cause visual field loss or optic disc changes
  • Cannot do a reliable visual field test, or poor quality OCT images

The registry criteria, word for word

Show all 10 criteriaShow less

Who can take part

  • age ≥18 years
  • best corrected VA ≥20/40
  • IOP ≤24mmHg at the screening and baseline visits
  • progressive RNFL and/or GCIPL thinning by TPA or GPA over the past 3 years in at least one eye

Who cannot take part

  • patients with DM, kidney or liver diseases
  • cognitive impairment (e.g. Alzheimer's disease)
  • diseases that may cause visual field loss or optic disc abnormalities other than glaucoma
  • pathological myopia
  • inability to perform reliable visual field
  • suboptimal quality of OCT images; Both eyes of a patient will be included in the analysis if both eyesare eligible for inclusion

Where in Hong Kong

  • HKU Eye CentreWong Chuk Hang, Hong KongContact: Gilda LAITaking people

About the trial

What the trial wants to find out

Glaucoma, a chronic degenerative disease of the optic nerve, is the leading cause of irreversible blindness worldwide. Although lowering the intraocular pressure (IOP) has been shown to be effective to slow optic nerve degeneration, a significant portion of glaucoma patients continue to develop progressive loss in vision despite adequate control of IOP. Development of neuroprotective therapy to prevent optic nerve degeneration by mechanisms other than IOP- lowering is critical to reduce the burden of glaucoma blindness. With 76 million glaucoma patients in 2020 worldwide, the need to investigate neuroprotection for glaucoma is pressing. While metformin is a widely adopted oral hypoglycemic medication for treatment of type 2 diabetes mellitus (DM), increasing evidence from clinical studies has shown that metformin can decrease the risk of many age-related diseases including neurodegenerative diseases. In a retrospective study of 150,016 patients with DM, those taking metformin at >1500mg/day had a 25% reduced risk of development of open-angle glaucoma than those who took no metformin. Metformin has a high safety profile. The investigators aim to investigate whether metformin can be repurposed to a neuroprotective therapy for glaucoma patients in a randomized controlled trial.

Read full original descriptionShow less

The investigators propose to conduct a 24-month, double-blind, placebo-controlled, parallel group, randomizing 125 primary open angle glaucoma patients who have progressive retinal nerve fiber layer (RNFL) and/or ganglion cell inner plexiform layer (GCIPL) thinning in at least one eye, as determined by optical coherence tomography Trend-based Progression Analysis (TPA) or Guided Progression Analysis (GPA), to receive metformin 1500mg/day or placebo. All patients will be followed up at 2-month intervals for IOP, RNFL thickness, and visual field (VF) measurements. The objectives are to compare (1) the rates of change of average RNFL thickness (primary outcome measure), and (2) the rates of change of VF mean deviation (MD) (secondary outcome measure) between treatment groups. The investigators hypothesize that patients treated with metformin have a slower rate of RNFL thinning, and a slower rate of VF MD decline compared with those treated with placebo at similar levels of IOP over the 24-month follow-up. The proposed study has the potential to mark a paradigm shift in the management of glaucoma patients by demonstrating that neuroprotection is attainable with metformin, which will alleviate the increasing burden of glaucoma blindness in China and other Asian countries where glaucoma patients with normal levels of IOP are prevalent. Furthermore, it will inform and impact the study design in future neuroprotection trials which can expedite the development of neuroprotective therapy for glaucoma.

The 2 groups in the trial

  • MetforminExisting treatment, for comparison

    Oral administration

  • PlaceboPlacebo, for comparison

Questions to ask the study team

  1. How often do I need to come in, and for how long each time?
  2. Are travel costs paid?
  3. Can I keep my own doctor?
  4. What happens if I want to stop?

Contact the study team: see the registry record → Contacts and Locations

Print a page for my doctor

Data and sources

Registry record
Listed on ClinicalTrials.gov.
Official title
Metformin as a Neuroprotective Therapy for Glaucoma - A Randomized Controlled Trial
Plain-language title
Tests metformin to protect the optic nerve in glaucomaGenerated from the registry record. The registry title is the official one.
AI summary
From the trial's eligibility criteria. Read by machine on 12 November 2026.
Record updated
20 November 2025