Age-Related Macular Degeneration
Age-related macular degeneration (AMD) is the most common cause of severe vision loss in the elderly population. It affects the central area of the retina called the macula, which is responsible for crisp, detailed vision required for activities such as reading and driving. It usually does not affect peripheral vision. There are two forms of the condition, the earlier dry (non-neovascular) and more advanced wet (neovascular) macular degeneration. Ninety percent of people with macular degeneration have the dry form and experience gradual loss of vision, while ten percent of individuals with macular degeneration have the wet form and experience rapid, severe vision loss. Deposits known as drusen form under the retina which, over time, can grow in size and number leading to visual symptoms. Abnormal blood vessel growth (neovascularization) can eventually develop in the macula and lead to significant loss of vision.
Visual symptoms are variable in the early stages and can affect one eye more than the other. Central vision can become blurry, distorted, wavy or dark as the disease progresses. Increased presence of drusen and development of neovascularization in the retina are associated with the progression of the visual symptoms.
Oxidative stress appears to play a major role in the development of macular degeneration. Elements produced by the environment can damage human cells. This damage combined with a genetic tendency or family history of macular degeneration increases the risk for developing this condition. Other risk factors include smoking and high cholesterol levels. AMD is diagnosed based on the findings of a dilated eye exam and retinal imaging studies.
Currently, nutritional supplements are used to treat dry or non-neovascular AMD. Antioxidant vitamins, zinc and lutein have been shown in large scientific studies to lower the risk of progression to the more advanced form of the condition by about twenty-five percent. The most current treatments for wet or neovascular AMD involve injections of medications into the eye that stop blood vessel growth and bleeding. These medications are called VEGF blockers or anti-VEGF agents. They target a chemical known as Vascular Endothelial Growth Factor which is responsible for the abnormal blood vessel growth characteristic of AMD. Other long established, yet effective treatments which are used in selected cases include thermal laser and photodynamic therapy.