Age-related Macular Degeneration (AMD) may now be less common than in the past

Age-related macular degeneration (AMD) is the leading cause of severe visual impairment in persons over 65 years of age, a group that is growing in numbers because of increased life expectancy.  AMD affects the center of the retina, the macula, where collection of fluid, fatty deposits, pigmentary changes, and blood, may cause significant visual impairment in about 10% of patients affected by ‘wet’ AMD. The rest 90% suffer from the non-progressive type of AMD, referred to as ‘dry’ AMD, where the features do not progress, and the vision largely remains stable, or deteriorates slowly.

AMD was considered to be more common in the Caucasian (or white) population, though recent studies from India indicate that the prevalence in India may be almost equal to the western population.

In the west, the prevalence was considered to be about 9.4 percent of US patients, based on a 1988-1994 Third National Health and Nutrition Examination Survey. But a recent study indicates the prevalence to be 6.5 percent in patients aged 40 and older, lower than the 9.4 percent reported earlier.

The new study involved 5,533 US adults, aged 40 years of older, who participated in the 2005-2008 National Health and Nutrition Examination Survey. Based on the digital photographs taken of both eyes, the researchers found that 6.5 percent of the participants had signs of some level of AMD, including tiny yellow or white deposits in the retina, pigment changes and deterioration of the retina and surrounding tissue. Less than one percent had the ‘wet’ disease, the advanced stage in which eyesight is more severely affected.

Extrapolating these new figures, an estimated 7.2 million people in the U.S. having any degree of AMD, with about 890,000 of these with advanced ‘wet’ disease. If that rate was correct and remained unchanged, it would mean about 18 million Americans should demonstrate signs of AMD. The new estimates represent a reduction of more than 30 percent in rates of AMD. The reasons for such a decrease in numbers is not very clear. The researchers feel it could reflect changes in time in smoking, diet and use of medications (anti-oxidant vitamins and zinc). A better understanding of the reduction of AMD in older population could help point to new prevention strategies that could lead to further reduction in numbers.

If we extrapolate the same percentage to Indian population, as some studies have indicated that the prevalence of AMD in Indian patients matches those of the western world, we have about 65 million patients in India. 

Source: Archives of Ophthalmology Jan 2011. Click here for the paper.