Age-related macular degeneration, or AMD, is the leading cause of vision loss and blindness in Americans over the age of 65. Since this demographic is increasing in number, sight loss caused by AMD is a growing concern and is often not understood by those who suffer from the condition.
Age-related macular degeneration (AMD) is a disease of the retina. It is largely caused by damage to the macula, a small spot near the center of the retina, which can affect the patient’s ability to see fine details if damaged. In early, less advanced AMD, visual symptoms are generally mild and may or may not impact vision-related activities. However, advanced stages of AMD can result in severe loss of sight in the central part of the vision. End-Stage AMD is the most advanced form of the disease and the leading cause of irreversible loss of vision and legal blindness in individuals over the age of 65. This blind spot is different than the visual disturbances experienced with cataracts (clouding of the eye’s lens) and cannot be corrected with cataract surgery or eyeglasses.
Age-related macular degeneration occurs when the arteries that nourish the retina harden. Deprived of nutrients, the retinal tissues begin to weaken and die, causing sight loss. Patients may experience blurriness, grey or distorted areas, and possibly a blind spot in the center of their vision. Macular degeneration does not cause total blindness because it doesn’t affect the peripheral vision. Possible risk factors include genetics, age, diet, smoking and sunlight exposure. Regular eye exams are highly recommended to detect macular degeneration early and prevent permanent loss of vision.
There are two forms of macular degeneration: dry or non-neovascular and wet or neovascular. Neovascular refers to the growth of new blood vessels into the macula, where they should not be. The dry form of AMD is more common than the wet form; however, wet AMD usually leads to more severe vision loss.
Dry AMD is an early stage of the disease which can result from aging and thinning of macular tissue. Eye doctors often see pigment changes and yellow spots in the macula. These yellow spots are called drusen and are thought to be accumulations of waste material from deteriorating tissue. Gradual loss of best corrected central vision may occur with the dry form of AMD, but it is typically not as severe as the vision loss caused by wet AMD. However, early forms of dry AMD can eventually lead to late-stage geographic atrophy, which may cause severe vision loss.
In about ten percent of individuals with AMD, dry AMD progresses to the wet form, the more damaging form of the disease. New blood vessel growth under the macula leads to leakage of fluid and blood, which causes permanent damage to the retina. Once the retina becomes damaged and dies off, this can lead to blind spots in the central vision.
In the early stages of the disease process, the patient may not have any visual changes or symptoms of vision loss. The macula is the central most portion of the retina. It is the area of the retina that we use to see 20/20 vision. It is the portion of our retina that we use to look at someone’s face from across the room. As the disease process progresses, some of the more common signs and symptoms of dry AMD include the following:
Other risk factors may include:
At this time, there is no cure for end-stage AMD and no way to reverse its effects. The type of treatment for the disease depends on what stage the degeneration is in the early, dry form stage or in the more advanced, wet form stage that can lead to serious loss of vision.
Many believe that certain nutrients such as zinc, copper, lutein, zeaxanthin and vitamins C and E – can help slow down the progression of dry macular degeneration. In addition, high levels of antioxidants and zinc have shown promising results.
For the wet and more serious form of macular degeneration, treatments aimed at stopping abnormal blood vessel growth include FDA-approved drugs of Lucentis, Avastin, Eyelea and Visudyne used with Photodynamic Therapy or PDT.