Doctors have found that metformin, an everyday medicine for diabetes, is associated with less progression of age-related macular degeneration (AMD), the commonest cause of blindness in western countries.
People with diabetes over the age of 55 years taking metformin were 37% less likely to develop the intermediate stage of AMD over a five year period compared to those not taking metformin.
AMD is a disease which affects the central retina or macular at the back of the eye. It eventually causes the light-sensitive tissue to die off (geographic atrophy, a form of 'dry' AMD) or be damaged by abnormal blood vessel growth ('wet' AMD). Intermediate and advanced AMD affects 10-15% of people over 65 years of age (1.1 to 1.8 million people in the UK), and is the commonest cause of blindness in high-income countries.
The annual cost of AMD is estimated to be £11.1billion in the UK. Geographic atrophy has no treatment in the UK and Europe, while treatments for wet AMD are expensive and unpleasant (repeated injections into the eye).
The research from the University of Liverpool used pictures taken of the eyes of 2,000 people attending the routine diabetic eye disease screening programme in Liverpool over 5 years. The researchers assessed whether AMD was present on the photographs and how severe it was, and then compared those taking metformin and those who were not. They also adjusted for factors which might bias the result such as age, sex, and duration of diabetes. The odds of developing intermediate AMD over 5 years in the metformin group was 0.63 compared to the no metformin group (95% confidence range 0.43 to 0.92).
A potential benefit from metformin in AMD has been suspected before, but this is the first study to grade AMD from eye photographs. Previous studies on metformin have used secondary information on AMD such as GP diagnostic codes, or insurance claims in the US.
Dr Nick Beare, an eye doctor who led this research, says: "Most people who suffer from AMD have no treatment, so this is a great breakthrough in our search for new treatments. What we need to do now is test metformin as a treatment for AMD in a clinical trial. Metformin has the potential to save many people's sight."
The research paper is published in the BMJ Open Ophthalmology: http://dx.doi.org/10.1136/bmjophth-2025-002339
