Macular degeneration is usually related to aging and is therefore called Age Related Macular Degeneration (ARMD or AMD). AMD is caused by a hardening of the arteries that restricts the amount of oxygen the retina receives. Most patients with AMD begin to notice problems with vision after age 50 and it is thought to be hereditary.
AMD begins with the appearance of yellowish spots under the retina called drusen. These spots usually have no effect on vision by themselves. While most people with drusen never have a substantial loss of vision or develop AMD, those that do usually begin to lose vision in just one eye. Later, the other eye may be affected as well.
When vision is lost in an eye, it may never be detected by the patient because the good vision in the other eye helps to compensate for the lost vision. AMD affects the central vision (called the macula). Central vision is used to see details (like reading, threading a needle, driving). Only when AMD affects both eye does it become challenging to do tasks requiring detailed vision (such as reading or driving). Because AMD threatens central vision, it is important to monitor changes in vision on a daily basis, especially if the doctor has told you that you have drusen or early macular degeneration.
A person with advanced AMD who has lost the ability to see detail with each eye rarely loses peripheral vision and can learn to function quite well. It is rare for a person with AMD to lose both central vision and peripheral vision.
AMD is generally classified as either "dry" (non-neovascular) or "wet" (neovascular). All patients with AMD begin as the "dry" form of the disease and then approximately 10% of patients who have macular degeneration develop "wet" AMD. In patients with "wet" AMD, the body begins to grow new blood vessels under the retina (neovascularization). The problem is that these new blood vessels are fragile, leak and can cause damage to surrounding tissues. The "dry" form of AMD is more common and often less severe.
Patients with AMD or at risk for the disease should perform an Amsler grid test at home each day.
Signs and Symptoms
- blurred vision
- distorted vision, straight lines look crooked
- dark or gray spot in central vision
- colors appear different in each eye
- objects appear different sizes in each eye
- difficulty performing tasks requiring detail vision
The doctor will perform a dilated fundus exam and most likely will also perfom a fluorescein angiogram to detect AMD and its severity. The doctor is looking for pigmented areas, leakage and other possible indications of AMD.
There is no proven effective form of laser treatment for "dry" AMD. For select "wet" AMD patients, laser therapy can be an effective treatment for sealing leaking blood vessels. While laser treatment usually does not restore lost vision, it can help prevent additional loss.
A recent study called AREDS (The Age Related Eye Disease Study) conducted by The National Eye Institute (NEI) has determined that the use of a specific combination of antioxidant vitamins reduces the risk of developing advanced stages of AMD by up to 25 percent. These high levels of antioxidants and zinc are the first effective treatment to slow the progression of AMD. The nutrients are not a cure for AMD, nor will they restore vision already lost from the disease. But they are playing a vital role in helping people at high risk for developing advanced AMD keep their vision. In the same study, the antioxidant and zinc combination showed no significant effect on the development or progression of cataracts.