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Effect of Metformin on Disease Progression and OCT Biomarkers in Patients with Intermediate Age‑Related Macular Degeneration

Registered drugNo placebo
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What is this trial about?

A plain-language summary of the goals, design and what participants do

Intermediate Age-related Macular Degeneration is an eye condition that affects the central part of the retina, leading to gradual loss of sharp, detailed vision. The study examines whether Metformin, a medication commonly used to treat high blood sugar, can help slow or prevent the disease from advancing to a more severe stage.

The purpose of the study is to assess the effect of Metformin in preventing the progression of intermediate AMD to advanced disease while participants continue their usual eye care. Volunteers will be randomly assigned to receive either Metformin or a placebo and will attend regular check‑ups over about two years. During these visits, simple, painless eye scans such as optical coherence tomography will be performed to create detailed pictures of the retina.

Researchers will watch for any signs that the eye condition gets worse and will also monitor participants for any side effects from the medication. The information gathered will help determine whether Metformin could be a useful addition to standard treatment for this form of macular degeneration.

The research process

The trial runs in 8 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Screening and Baseline Assessments

    You will undergo a series of eye examinations to evaluate the condition of your macula. These include optical coherence tomography (OCT) to obtain detailed images of retinal layers, fundus autofluorescence to detect changes in retinal pigment, and OCT angiography (OCTA) to visualize blood vessels.

    Blood samples will be taken to check general health and to establish baseline laboratory values.

    Your medical history and current medications will be reviewed to confirm eligibility for the study.

  2. Step 2

    Randomization and Assignment

    After the baseline assessments, you will be randomly assigned to receive the study medication. This assignment is made by the study system and you will not need to make any decision.

  3. Step 3

    Start of Study Medication

    You will begin taking Metformin 1000 mg per day, administered as one film‑coated tablet taken by mouth each day.

    The medication will be taken for the entire study period of 24 months unless you are advised otherwise by the study team.

  4. Step 4

    First Follow‑Up Visit (6 Months)

    Six months after starting the medication, you will return for a follow‑up visit.

    During this visit, the same eye imaging tests (OCT, fundus autofluorescence, OCTA) will be repeated, and blood samples will be collected to monitor any changes.

    The study staff will ask about any side effects you may have experienced and check that you are taking the medication as prescribed.

  5. Step 5

    Second Follow‑Up Visit (12 Months)

    At the 12‑month mark, you will have another set of eye examinations and blood tests similar to the 6‑month visit.

    Medication adherence and any new symptoms will be reviewed.

  6. Step 6

    Third Follow‑Up Visit (18 Months)

    At 18 months, the study will repeat the imaging and laboratory assessments to track the progression of intermediate age‑related macular degeneration.

    Your experience with the medication will be discussed again.

  7. Step 7

    Final Follow‑Up Visit (24 Months)

    After 24 months of treatment, you will undergo the final set of eye imaging tests and blood work.

    The study will determine whether the disease has progressed to the late stage based on the imaging results.

    All study data will be collected, and the study medication will be discontinued.

  8. Step 8

    Unscheduled Visits (If Needed)

    If you notice any new visual changes or experience side effects, you may be asked to attend an unscheduled visit for additional evaluation.

    These visits follow the same procedures as the scheduled visits to assess eye health and medication safety.

Who can join the trial?

5 criteria

  • You are 55 years of age or older, and you can be male or female.
  • You have intermediate age‑related macular degeneration (iAMD) in at least one eye, which means your eye shows either large “drusen” (tiny yellow deposits under the retina that are 125 µm or larger) or pigment changes together with at least one medium‑size drusen (63 µm to 124 µm).
  • Your eye must also have at least one “high‑risk” sign seen on an eye scan called optical coherence tomography (OCT). These signs include any of the following: incomplete retinal pigment epithelial and outer retinal atrophy (iRORA), disruption of the ellipsoid zone (EZ), presence of hyperreflective foci, or a new blood‑vessel growth (a neovascular lesion) in the other eye.
  • Only one eye will be used for the study; if both eyes meet the requirements, the study eye will be chosen at random before you are assigned to a treatment group.
  • You must be able to sign a written agreement (called informed consent) and be willing to follow all study visits and procedures.

Who cannot join the trial?

11 criteria

  • Images of the eye taken with SD‑OCT (Spectral Domain Optical Coherence Tomography) are not clear enough for the study.
  • You are currently using medicines that can harm the retina, such as hydroxychloroquine, chloroquine, pentosan polysulfate sodium, tamoxifen, or MEK inhibitors.
  • You are already enrolled in another interventional clinical trial.
  • Your prescription for glasses or contact lenses is very strong (a refractive error of 6 diopters or more).
  • You have advanced AMD (called late AMD) or any sign of fluid, bleeding, leaking material, or scar tissue in the eye being studied.
  • You have ever had retinal surgery, laser treatment, a blockage of retinal blood vessels, anti‑VEGF injections, or a hereditary retinal or macular disease.
  • You have diabetes (a previous diagnosis, are taking diabetes medication, have an HbA1c ≥ 6.5 % or a fasting blood sugar ≥ 126 mg/dL). Prediabetes does not exclude you.
  • You have taken the study drug metformin before.
  • Your kidney function measured as estimated glomerular filtration rate (eGFR) is below 60 mL/min/1.73 m².
  • You are currently using any medicine that lowers blood sugar, including GLP‑1 receptor agonists or SGLT2 inhibitors.
  • You have any known contraindication to metformin, such as an allergy to metformin or its ingredients, severe metabolic acidosis, diabetic pre‑coma, acute conditions that could affect kidney function, diseases causing low oxygen in tissues, severe liver disease, acute alcohol intoxication or alcoholism, or a mitochondrial disease.
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Investigated drugs

Metformin is an oral tablet taken by mouth. In this study it is being tested to see if it can help slow down the worsening of intermediate age‑related macular degeneration (AMD) and keep the disease from reaching a more severe stage. Participants will continue any usual eye care they receive, and the researchers will compare the outcomes of those who take metformin with those who do not, to find out if the drug offers extra protection for the eyes.

What is already known about the treatment

Metformin - Metformin is taken by mouth as a film‑coated tablet, usually 500 mg per dose. It is a well‑established drug that is widely used and studied for treating type 2 diabetes. The main therapeutic use is to lower blood sugar by reducing the liver’s glucose production and helping the body’s cells use sugar more effectively. It belongs to the biguanide class of oral hypoglycemic agents.

Investigated diseases

Intermediate age‑related macular degeneration - A condition in which the central part of the retina begins to show yellowish deposits and subtle thinning, affecting people usually over middle age. Vision may still be relatively clear, but small changes in the retinal tissue can be detected with imaging. Over time the disease can advance to a later stage where larger areas of damage appear, leading to loss of fine detail and central vision blur. The progression involves further breakdown of the retinal pigment layer and growth of abnormal blood vessels beneath the retina. This later stage can result in noticeable difficulty reading, recognizing faces, or performing tasks that require sharp central sight.
Trial detailsLast updated 8 Nov 2026
Age18+ yearsPhasePhase IITrial ID2025-522990-12-00Protocol code001Estimated enrolment140 patientsSponsorUnidade Local De Saude De Sao Jose E.P.E.

sourced from the EU Clinical Trials Register and site verification

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Prefer not to search on your own, or looking for clinical trials for a rare disease? Our clinical trial advisor will do it for you.

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