Macular degeneration is an eye disorder that makes it difficult to see fine details. The condition affects the macula, the part of the retina responsible for central vision.
Age-related macular degeneration (AMD), AMD, Senile macular degeneration (SMD)
Causes, incidence, and risk factors:
Damage to the macula can gradually destroy central vision, which is used to read and see objects clearly.
Two types of macular degeneration (AMD) exist:
- Dry macular degeneration occurs when the macula becomes thin and dries out. Small yellow deposits, called drusen, form under the macula. As these drusen increase in size and number, they create a blurred spot in the central vision of the eye. Almost all people with macular degeneration have the dry form.
- Wet macular degeneration occurs when abnormal blood vessels grow under the macula and retina (this is called choroidal neovascularization). These vessels can leak blood and fluid, damaging the macula. Vision loss in the central vision can occur very quickly. Only about 10 percent of people with macular degeneration have this form, but it causes most of the vision loss associated with the condition.
Scientists aren’t sure what causes AMD. The disease is most common in people over 60, which is why it is often referred to as age-related macular degeneration.
Other risk factors are:
- Caucasian race
- Cigarette smoking
- Family history
- Female gender
At first you may not have symptoms. As the disease progresses, your central vision can be affected.
The most common symptom in dry AMD is blurred vision. As the disease progresses, you may need more light to read or perform everyday tasks. The blurred spot in the center of vision gradually gets larger and darker. In the later stages, you may not be able to recognize faces until people are close to you.
AMD typically does not affect side (peripheral) vision. This is very important, because it means you will never have complete vision loss from this disease.
The most common early symptom of wet macular degeneration is that straight lines appear distorted and wavy. You may also notice a small dark spot in the center of your vision that gradually gets larger.
Signs and tests:
If you are over age 60 and you’ve had changes in vision, your eye care provider will do an examination. During the exam, the doctor will use drops to enlarge (dilate) your pupils, and a special magnifying lens to view your retina and optic nerve. The doctor will look for the yellow deposits called drusen that form in dry macular degeneration.
You may be asked to cover one eye and look at a pattern of lines called an Amsler grid. If the straight lines appear wavy, it may be a sign of AMD.
Other tests for macular degeneration may include:
No treatment exists for dry macular degeneration. However, a combination of antioxidants and zinc may slow the progression of the disease. Smokers should not use this treatment.
The recommended supplements contain:
- 500 milligrams of vitamin C
- 400 International Units of beta-carotene
- 80 milligrams of zinc
- 2 milligrams of copper
Although there is no cure for wet AMD, treatments may include:
- Laser surgery (laser photocoagulation) -- a small beam of light destroys the abnormal blood vessels.
- Photodynamic therapy -- a light activates a drug that is injected into your body to destroy leaking blood vessels.
- Special medications that slow the formation of new blood vessels in the eye (anti-angiogenesis (anti-VEGF) therapy) -- drugs such as bevacizumab (Avastin) and ranibizumab (Lucentis) are injected into the eye to stabilize or improve vision.
Low-vision aids (such as special lenses) and therapy can help improve your vision and quality of life.
Most people with mild dry macular degeneration will not have disabling central vision loss. However, there is no way to predict who will progress to a more severe form of the disease.
The wet form of macular degeneration often leads to significant vision loss.
This disorder results in the loss of central vision only -- macular degeneration cannot cause peripheral vision loss.
Loss of central vision may interfere with many daily activities, such as reading, working on the computer, or driving. You may need extra light or magnification to perform many of your normal activities.
Calling your health care provider:
If you have AMD, your health care provider may recommend that you check your vision every day on an Amsler grid. Call your provider if the lines appear wavy, or you notice any other changes in your vision.
Although there is no known way to prevent macular degeneration, lifestyle factors can reduce your risk of developing the condition:
- Don't smoke
- Eat a healthy diet with plenty of fruits and vegetables
- Maintain a healthy weight
See your eye care professional regularly for dilated eye exams.
Gohel PS, Mandava N, Olson JL, Durairaj VD. Age-related macular degeneration: an update on treatment.Am J Med. 2008 Apr;121(4):279-81.
Martidis A, Tennant MTS. Age-Related Macular Degeneration. In: Yanoff M, Duker JS, Augsburger JJ, et al, eds. Ophthalmology. 2nd ed. Philadelphia, Pa: Mosby Elsevier;2004:chap 125.