Eye drops that could prevent one of the most common causes of blindness are being developed by scientists.
Researchers have found that lowering the levels of cholesterol in the eye can halt the growth of blood vessels which cause age-related macular degeneration (AMD).
The disease is the leading cause of blindness in people as they get older.
It occurs when blood vessels grow excessively beneath retina at the back of the eye, resulting in bleeding and scarring, which causes patients to gradually lose their vision from the centre outwards.
Researchers at Washington University School of Medicine have found that using eye drops that lower cholesterol can prevent the harmful blood vessels from growing in animal models.
Tests on human cells taken from patients with AMD also showed promising effects in the laboratory.
The researchers say existing drugs used to prevent cholesterol build up in heart patients could be adapted for use in the eye.
They now hope to conduct the first clinical trials in patients within the next five years.
"These results have significant therapeutic implications," said Dr Rajendra Apte, an ophthalmologist at Washington University School of Medicine who led the study.
"We may be able to modify drugs that already are available and use them to deliver treatment to the eye."
Dr Rajendra and his colleagues, whose work is published in the journal of Cell Metabolism, found a key link between macular degeneration and cholesterol can build up in white blood cells known as macrophages – which are an important part of the immune system and cause inflammation.
With age, these white blood cells can become bloated with cholesterol and can cause new blood vessels to grow underneath the retina in the eye.
This excessive growth of new blood vessels can cause them to rupture and lead to the retina becoming scarred, causing loss of the light sensitive cells at the back of the eye, and so blindness.
Dr Apte found that drugs which help macrophages to rid themselves of cholesterol stopped the growth of new blood vessels in the eyes of ageing mice with AMD.
Immune cells taken from human AMD patients also showed greater ability to inhibit blood vessel growth when given the drugs in the laboratory.
The researchers looked at two cholesterol regulators in their study and found they both reduced blood vessel growth. They believe using several drugs in combination may improve the treatment further.
Dr Apte said that eye drops that lowered cholesterol in macrophages could be given to patients at risk of developing AMD, which is often hereditary, or for those in the early stages.
Dr Apte said: "People with earlier stages of AMD could potentially be treated with the aim of delaying or preventing progression."
Cathy Yelf, from the Macular Society, which supports research into macular degeneration, welcomed the research.
She said: “Finding a way of preventing late-stage macular degeneration from developing would be the best way of overcoming it.
Richard Gray Telegraph.co.uk