Researchers at the University of Liverpool have found that metformin, a common diabetes med, might help prevent age-related macular degeneration (AMD), the leading cause of blindness in Western countries.
In a study of 2,000 people with diabetes, those taking metformin were 37% less likely to develop intermediate AMD over 5 years. 
The researchers analysed eye photos and adjusted for factors like age and sex.
This is a big deal, as AMD affects 1.1-1.8 million people in the UK and costs £11.1 billion annually. And currently, there’s no treatment for geographic atrophy (dry AMD) in the UK and Europe.