Eye drops designed to lower cholesterol may be able to prevent one of the most common forms of blindness, according to US researchers.
They showed how high cholesterol levels could affect the immune system and lead to macular degeneration.
Tests on mice and humans, published in the journal Cell Metabolism, showed that immune cells became destructive when they were clogged with fats.
Others cautioned that the research was still at an early stage.
The macula is the sweet spot in the eye which is responsible for fine detail. It is essential for reading, driving and recognising people's faces.
Macular degeneration is more common in old age. It starts in a "dry" form in which the light-sensing cells in the eye become damaged, but can progress into the far more threatening "wet" version, when newly formed blood vessels can rapidly cause blindness.
Doctors at the Washington University School of Medicine investigated the role of macrophages, a part of the immune system, in the transition from the dry to the wet form of the disease.
One of the researchers, Dr Rajendra Apte, said the role of macrophages changed and they triggered the production of new blood vessels.
"Instead of being protective, they accelerate the disease, but we didn't understand why they switched to become the bad cells," he told the BBC.
Normally the cells can "eat" fatty deposits and send them back into the blood.
However, their research showed that older macrophages struggle. They could still eat the fats, but they could not expel them. So they became "bloated", causing inflammation which in turn led to the creation of new blood vessels.
Dr Apte said: "Based on our findings, we need to investigate whether vision loss caused by macular degeneration could be prevented with cholesterol-lowering eye drops or other medications that might prevent the build-up of lipids beneath the retina."
Clara Eaglen, from the charity RNIB for the visually impaired, said: "This new research is very interesting as it shows that cholesterol-lowering drugs could be used to prevent thousands of people losing their sight unnecessarily from conditions such as AMD [age-related macular degeneration] - the biggest cause of sight loss in the UK.
"The more aggressive of the two forms, wet AMD, can take your central vision in as little as three months if left untreated.
"Clearly this research is still at an early stage but it will be exciting to watch how it progresses and at some point cholesterol-lowering eye drops may become part of a growing army of treatments for sight-threatening eye conditions."