George Ayles has already lost the sight in his right eye
Scientists from Southampton university claim to have discovered a gene responsible for the most common cause of blindness in the western world.
One in three people will be affected by age-related macular degeneration (AMD) by the time they are 75.
The discovery of the gene, named Serping 1, in 25% of people with AMD opened the door to better treatments and screening, the researchers said.
AMD affects the area at the back of the eye which allows us to see fine detail.
George Ayles, 86, has been found to be a carrier of the Serping 1 gene.
Three years ago he lost the sight in his right eye and it is now affecting his left eye as well.
He said: "It does affect your confidence.
"Stepping off kerbs, going up and down stairs and bright sunlight is not good, it does glare your eyes."
Attacks the eye
The Serping 1 gene causes the immune system to overwork, attacking the eye, but the effects can take 70 years to develop.
More than 1,000 patients took part in the research programme, which has taken six years to complete.
It is hoped the discovery will help scientists develop new forms of treatment and early screening programmes.
Professor Andrew Lotery, from Southampton, said: "It means that we can diagnose people at an earlier stage and we can have more focused treatments, perhaps just even drugs therapies that we can provide before people develop the late stages of the disease.
"It totally changes our thinking about this disease and that's very important, to get better treatments."
Tom Bremridge, of the Macular Disease Society, said: "For the first time we're on the edge of getting a cure for macular degeneration. Up to now we've only been able to treat some forms of it.
"This is not big bang, but it's huge step forward"