A US study says that two genes could determine the vulnerability of the elderly to an advanced form of age-related macular degeneration (AMD), researchers report.
Age-related macular degeneration (AMD) is a disease associated with aging that gradually destroys sharp, central vision. Central vision is needed for seeing objects clearly and for common daily tasks such as reading and driving.
AMD affects the macula, the part of the eye that allows you to see fine detail. AMD causes no pain, though.
In some cases, AMD advances so slowly that people notice little change in their vision. In others, the disease progresses faster and may lead to a loss of vision in both eyes. AMD is a leading cause of vision loss in Americans 60 years of age and older.
Also people who smoked or were overweight faced an even greater risk of the potentially blinding eye condition, the new study found.
'The two genetic variants are related and predict to a certain extent which individuals who have earlier-intermediate forms of macular degeneration progress to the advanced form and visual loss,' explained the study's lead author, Dr. Johanna M. Seddon, director of the Ophthalmic, Epidemiology and Genetics Service in the department of ophthalmology at Tufts-New England Medical Center and New England Eye Center.
'Genetic variants are part of the way we can differentiate who gets worse, coupled with environmental factors like a high body mass index and smoking,' said Seddon, whose team published its results in the April 25 issue of the Journal of the American Medical Association.
The findings have implications for the prevention of AMD, one expert said.
'They've actually identified specific genes and specific abnormalities in specific genes that prove that macular degeneration has a strong genetic component,' said Dr. Robert Cykiert, clinical associate professor of ophthalmology at New York University School of Medicine in New York City. 'What this says is if you have someone in your immediate family such as parents or siblings with AMD, then you need to see an ophthalmologist and be carefully followed, because there are things that can be done to prevent progression.'
Down the line, there may even be a blood test to detect these genes, further brightening the picture for prevention and early treatment, Cykiert said.
But it's too early to recommend widespread screening, the authors stated.
'Some individuals who progress do not have these genetic variants or have never smoked,' Seddon said. 'We need to refine this predictive measure, add more genetic variants and maybe even more environmental factors.'