Their study of identical twins from the US World War II Twin Registry also found that the more a person smoked, the higher their risk of developing macular degeneration. The study is the first to look at identical twin pairs in which one twin had early age-related macular degeneration (AMD), and the other had late stage AMD.

AMD is highly heritable, with genetic factors determining up to 71 percent of the disease’s severity as determined by a previous study of this twin registry by this same research team. By examining identical twins with the same genes but whose disease was at different stages, researchers were able to identify environmental and behavioral factors that may contribute to severity of the disease.

“Eat a healthy diet with lots of fruits and vegetables, and that can make a difference - even if you have a genetic susceptibility to macular degeneration, and, of course, don’t smoke,’’ said Doctor Johanna M. Seddon, Director of the Epidemiology and Genetics Service, Tufts Medical Center, and Professor of Ophthalmology, Tufts Universtity School of Medicine.

Macular degeneration is one of the leading causes of vision loss in older Americans. It occurs when cells in the macula, the part of the eye responsible for clear central vision, gradually die. Macular degeneration can progress so slowly it takes years for serious vision loss to occur but it can also develop rapidly, causing severe vision loss that can make it difficult to drive, read or conduct daily tasks.

Each twin completed a questionnaire about nutritional and health behaviors. The study found that twins whose macular degeneration was at the early stages tended to consume more vitamin D from dietary sources such as fish or milk than their brothers. Vitamin D may reduce the risk of macular degeneration because it has anti-inflammatory properties. It may also block the formation of new blood vessels that can grow under the macula, leaking blood and causing vision loss in the more severe stages of the disease.


MEDICA.de; Source: Tufts Medical Center