Age-related macular degeneration (AMD) is the leading cause of blindness in people over 60. An estimated 1.8 million people in the U.S. are afflicted with this disease, while an additional 7.3 million are at increased risk, according to the Centers for Disease Control (CDC).
What Is AMD?
In AMD, the middle part of the retina in the back of the eye degenerates, leading to a decrease in central vision. Two forms of the disease can occur. One is a “dry” form called atrophic, while the other is a “wet” form called exudative macular degeneration.
Approximately 80% of people suffering from this disease have the “dry” form. There is no known treatment for atrophic AMD, and vision cannot be restored once it is lost. However, that may soon change thanks to recent work by a research team led by Kang Zhang, MD, PhD., a professor of ophthalmology and human genetics at Shiley Eye Center at the University of California San Diego.
What Causes AMD?
The exact cause of AMD has been a mystery. Besides advanced age, factors for increased risk of AMD include being Caucasian, having a diet rich in saturated fats, high cholesterol levels, being overweight, smoking cigarettes, high blood pressure, and having a family history of the disease.
It is speculated that viral infections may play a role in the disease by inducing an inflammatory response that leads to AMD. A molecule called toll-like receptor 3 (TLR3), also known as CD283, normally supports the body’s immune defenses. It does this by alerting the immune system of a possible viral infection.
The link between AMD and TLR3 was discovered by Dr. Zhang and his team of researchers. A paper they published in 2008 discussed their discovery of the first gene associated with a severe form of atrophic AMD. This finding is especially important because treatment that is being experimentally administered to patients with another form of AMD may cause more damage to patients with this more severe form.
Future Prospects for Treatment
The finding of a link between AMD and TLR3 may lead to novel therapies for the treatment of atrophic macular degeneration. The findings that there are different types of atrophic AMD will necessitate targeted therapies dependent on genetic profiles of individual patients.
AMD leads to potentially debilitating blindness in millions of adults all across America, but there is a proverbial light at the end of the tunnel. With continued understanding of its causes and targeted research efforts, one day a cure for macular degeneration may be in sight.