The front of the eye contains a lens that focuses images on the retina in the back of the eye. The retina contains special nerve cells that react to light.
Nerve cells are very close together in the middle of the retina, where the eye focuses the images that we see. This part of the retina is called the macula. The macula provides the sharp, straight-ahead vision that allows you to see small detail, read fine print, recognize faces and see street signs.
Macular degeneration is an eye disease and is the most common type of macular damage in adults. Because the disease develops as a person ages, it's often called age-related macular degeneration (AMD). AMD is the leading cause of vision loss in people over the age of 50 in the United States, Europe and many other parts of the world.
There are two types of AMD – the dry (atrophic) form and the wet (exudative or neovascular) form.
The dry form of AMD affects about 85-90% of AMD patients and usually begins when tiny yellow deposits called drusen appear in the macula. Drusen usually do not cause serious loss of vision, but can distort vision. However, for reasons not yet understood, sometimes drusen are associated with macular atrophy (thinning) and tissue breakdown, slowly leading to vision loss. Patients may have blind spots in their vision; in the advanced stages, patients may even lose central vision.
The wet form of AMD occurs in about 10-15% of AMD patients. It is caused by the growth of abnormal blood vessels beneath the macula that can leak fluid and blood into the eye. The wet form of AMD usually causes major vision problems, such as blind spots and loss of central vision in the affected eye, and can advance rapidly. These abnormal blood vessels eventually scar, leading to permanent retinal damage and loss of central vision.
Most patients with AMD have the dry form of the disease and will not lose central vision. However, the dry form of AMD can lead to the wet form. People who have the wet form of AMD are much more likely to have serious vision loss. For these patients, early diagnosis and treatment are important to save as much vision as possible.
Because the dry form can change into the wet form, it's very important for people with AMD to monitor their eyesight carefully and see their eye doctor on a regular basis.
AMD may be hereditary, meaning it can be passed on from parents to children. If someone in your family has or had the condition, you may be at higher risk for developing the disease. Talk to your eye doctor about your individual risk.
The exact causes of macular degeneration aren't known. Risk factors may include:
AMD often doesn't have symptoms and isn't recognized until it affects visual acuity (sharpness). The first symptom of AMD is usually noticed when straight lines appear wavy. This may lead to a gradual loss of central vision.
Other symptoms of AMD include the following:
If you have any of these symptoms, see an ophthalmologist (eye doctor) as soon as possible.
Your ophthalmologist will perform a complete examination to diagnose AMD. One of the most common early signs of AMD is the presence of drusen. Your doctor can see these during a routine eye exam. Often, an optical coherence tomography (OCT) picture will be taken. OCT shows how thick the retina is and can identify accumulated fluid from abnormal blood vessels. A new kind of OCT, “OCT angiography” can show some things a fluorescein angiogram (see below) can show but without the dye injection.
The doctor may order a fluorescein or indocyanine green angiogram to look for the abnormal blood vessels within or under the retina. During each of these procedures, dye is injected in the arm, and photographs (not X-rays) are taken from a special camera to track the movement of the dye as it reaches the eye, and to show any changes in the retina. If new vessels are leaking fluid or blood in the macula, the photographs show their location and type.
People with macular degeneration can check their own vision with a simple test called the Amsler grid. The Amsler grid is a pattern of straight lines that make perfect squares. The patient looks at a large dot in the middle of the grid and notices any areas where the lines look blurry, wavy or broken. If the grid lines seem to be more distorted than before, it might be a sign that the macular degeneration is getting worse and needs evaluation.
Early detection of AMD is very important because treatment can delay or reduce the severity of the disease.
Although there's no treatment to reverse the dry form of AMD, eyesight may be helped with low-vision aids, such as devices that have special lenses or electronic systems that produce enlarged images of nearby objects. They help people with partial vision make the most of their remaining vision.
The Age-Related Eye Disease study (AREDS) found that taking vitamin and mineral supplements can reduce some patients’ chances of developing AMD or reduce the chance of progression. For instance, Vitamins C, E, lutein, zinc and copper have been shown to decrease the risk of vision loss in patients with intermediate to advanced dry AMD. Ask your eye doctor if this type of therapy could work for you. The newest versions of the vitamins tend to have “AREDS 2” in the name or on the label.
Several options are available to treat the wet form of AMD, but not all are appropriate or successful for all patients. These treatments include:
Depending upon the cause of legal blindness, it is possible that treatment may help. If recent bleeding or leakage under the retina has resulted in legal blindness, surgery is a possibility. Retinal cell transplants and stem cell therapy are under study; a new implanted electronic retinal “chip” was recently approved for human use but is used for retinal degenerations and not yet for AMD.
Because bleeding or leakage may occur beneath the retina even after the laser treatment, it's possible that treatment with injected drugs can help.
Other medical conditions or age shouldn't be a factor if you're considered an appropriate candidate for treatment, although sometimes anti-VEGF injections may be delayed after a recent heart attack or stroke.
After treatment, your physician may order another OCT picture, or sometimes an angiogram, to make sure there are no other areas of blood leakage. If the OCT shows that there is still leakage, more treatment is usually recommended. There are various treatment schedules used, such as “as needed” or “PRN,” monthly, and “treat and extend” schedules. Talk to your doctor about what treatment schedule to anticipate. Most treatment is in the first year, but periodic injections are generally needed for five or even more years.
Rare complications may include:
Unfortunately, AMD can return even after successful treatment. The various treatments can slow the rate of vision loss and hopefully preserve some sight.
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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or healthcare provider. Please consult your healthcare provider for advice about a specific medical condition. This document was last reviewed on: 03/15/2016