A drug based on vitamin A could prevent millions from going blind as they get older, say researchers.
The treatment was able to stop the most common cause of blindness in old age during trials.
Researchers behind the drug, fenretinide, found it halted the advance of age-related macular degeneration, for which there is currently no cure.
They targeted the most prevalent form of the condition, known as 'dry' AMD, which is caused by the deterioration and death of cells in the macula - the part of the retina used to see straight ahead.
The disease robs sufferers of their sight by creating a blackspot in the centre of their vision, reports the Daily Mail.
It can make it impossible to carry out everyday tasks such as reading, driving and watching television.
While the less common 'wet' form can be treated, nothing can be done to help the bulk of patients.
The US research studied fenretinide, which is derived from vitamin A, the vitamin found in carrots, and which was originally designed to tackle arthritis.
Almost 250 men and women with dry AMD took a fenretinide pill a day or a placebo.
In the highest dose, the drug halted visual deterioration after a year. This suggests that while it was unable to do anything to stop cells that were already damaged from dying, it protected healthy cells.
Although the research is still preliminary, it offers promise of a treatment for the disease.
It affects millions across the world. The number of British sufferers could more than treble to one million within 25 years as the population ages.
Jason Slakter of New York University School of Medicine said: "There are currently no effective treatments for dry AMD and the need for finding one is grave."