Age-related macular degeneration (AMD) is a disease that affects your central vision. It is a common cause of vision loss among people over age of 60. Because only the center of your vision is usually affected, people rarely go blind from the disease. However, AMD can sometimes make it difficult to read, drive, or perform other daily activities that require fine, central vision.

What is the macula?
The macula is in the center of the retina, the light-sensitive layer of tissue at the back of the eye. As you read, light is focused onto your macula. There, millions of cells change the light into nerve signals that tell the brain what you are seeing. This is called your central vision. With it, you are able to read, drive, and perform other activities that require fine, sharp, straight-ahead vision.

How does AMD damage vision?

AMD occurs in two forms:
Dry AMD affects about 90 percent of those with the disease. Its cause is unknown. Slowly, the light sensitive cells in the macula break down. With less of the macula working, you may start to lose central vision in the affected eye as the years go by. Dry AMD often occurs in just one eye at first. You may get the disease later in the other eye. Doctors have no way of knowing if or when both eyes may be affected.

Wet AMD--Although only 10 percent of all people with AMD have this type, it accounts for 90 percent of all severe vision loss from the disease. It occurs when new blood vessels behind the retina start to grow toward the macula. Because these new blood vessels tend to be very fragile, they will often leak blood and fluid under the macula. This causes rapid damage to the macula that can lead to the loss of central vision in a short period of time.

Who is at risk for AMD?
Although AMD can occur during middle age, the risk increases as a person gets older. Results of a large study show that people in their 50s have about a two percent chance of getting AMD. This risk rises to nearly 30 percent in those over age 75. Besides age, other AMD risk factors include:
Gender--Women may be at greater risk than men, according to some studies.
Smoking--Smoking may increase the risk of AMD.
Family History--People with a family history of AMD may be at higher risk of getting the disease.
Cholesterol--People with elevated levels of blood cholesterol may be at higher risk for wet AMD.

What are the symptoms of AMD?
Neither dry nor wet AMD causes any pain. The most common symptom of dry AMD is slightly blurred vision. You may need more light for reading and other tasks. Also, you may find it hard to recognize faces until you are very close to them. As dry AMD gets worse, you may see a blurred spot in the center of your vision. This spot occurs because a group of cells in the macula have stopped working properly. Over time, the blurred spot may get bigger and darker, taking more of your central vision.

Normal	Early	Moderate	Advanced

Figure : Visual distortion in Age-related macular degeneration

An early symptom of wet AMD is that straight lines appear wavy. This happens because the newly formed blood vessels leak fluid under the macula. The fluid raises the macula from its normal place at the back of the eye and distorts your vision. Another sign that you may have wet AMD is rapid loss of your central vision. This is different from dry AMD in which loss of central vision occurs slowly. As in dry AMD, you may also notice a blind spot.
If you notice any of these changes in your vision, contact your eye care professional at once for an eye exam.

How is AMD detected?

Eye care professionals detect AMD during an eye examination that includes:

Visual acuity test: This eye chart test measures how well you see at various distances.

One of the most common early signs of AMD is the presence of drusen. Drusen are tiny yellow deposits in the retina. Your eye care professional can see them during an eye examination. The presence of drusen alone does not indicate a disease, but it might mean that the eye is at risk for developing more severe AMD.

While conducting the examination, your eye care professional may ask you to look at an Amsler grid. This grid is a pattern that resembles a checkerboard. You will be asked to cover one eye and stare at a black dot in the center of the grid. While staring at the dot, you may notice that the straight lines in the pattern appear wavy to you. You may notice that some of the lines are missing. These may be signs of wet AMD (See Amsler Grid below.) On the left is what an Amsler grid normally looks like, and the illustration on the right is how it might look to someone with AMD. These grids are reduced in size; ask your doctor for a full-size grid to use at home.

Normal Amsler Grid	Amsler Grid seen with AMD

If your eye care professional suspects you have wet AMD, you may need to have a test called fluorescein angiography (See figure below). In this test, a special dye is injected into a vein in your arm. Pictures are then taken as the dye passes through the blood vessels in the retina. The photos help your eye care professional evaluate leaking blood vessels to determine whether they can be treated.

Figure-2: Fluorescein angiogram showing growth of abnormal vessels under the retina in wet AMD

Another method for detecting and monitoring AMD is called Optical Coherence Tomography (OCT). This test provides a side view of the macula making it easy to detect any early fluid collection inside or underneath the retina. This test is very easy to administer and requires no injections.

           A. OCT of normal macula

     B. OCT of patient with wet AMD

How is AMD treated?

Dry AMD currently cannot be treated. But this does not mean that you will lose your sight. Fortunately, dry AMD develops very slowly. You may lose some of your central vision over the years. However, most people are able to lead normal, active lives--especially if AMD affects only one eye.

Wet AMD can be treated with several methods:

1. 1. Laser surgery: The treatment involves aiming a high energy beam of light directly onto the leaking blood vessels. Laser treatment is more effective if the leaky blood vessels have developed away from the fovea--the central part of the macula.
2. 2. Visudyne therapy: In this procedure, a light-activated drug known as Visudyne is injected into the patient's bloodstream. Once the drug reaches the retina, it is activated by a non-thermal laser (A laser that does not burn the retina). This produces a clot that closes the abnormal vessels without causing severe damage to the overlying sensory retina. The abnormal blood vessel may return after several months. However, Visudyne therapy can be reapplied at up to 3 month intervals if necessary.
3. 3. Eye Injections: A third new option is an injection inside the eye of a medication that tends to attack the abnormal vessels and decrease the leakage. There are several medications available clinically and several more are being developed. These injections currently need to be repeated every 4-6 weeks. The total number of injections you will receive will be discussed with by your doctor. This is a very exciting new treatment for wet AMD.

Your doctor will discuss with you all the different options suitable for your condition and help you in selecting a treatment plan.

How is the eye injection performed?

Eye injections are performed in your doctor’s office or eye clinic. You do not need any special preparation before getting the eye injection. You do not need to be fasting.

On the day of the procedure, you report to your doctor’s office like you normaly would for a routine visit. You will be dilated in the injected eye only. The eye is numbed and sterilized prior to the actual injection. There is no need to patch the eye after the injection. You will be given an antibiotic eye drop to use for several days after the injection.

You can leave the office once the treatment is done, but you will need someone to drive you home. Because your pupils will stay dilated for a few hours, you also should bring a pair of sunglasses.

For the rest of the day, your vision may be a little blurry. Your eye may also hurt a bit and you may see a red spot in the corner of the eye. This is easily controlled with drugs that your eye care professional can suggest.

You will need to make frequent follow-up visits. During each exam, you may have an OCT to make sure that the blood vessels are not still leaking, or that new blood vessels have not developed. You may also need a fluorescein angiography if the vessels continue to leak. It is important to realize that the eye injections are not a cure for AMD. It is only a treatment to help stop further vision loss and may return your vision to baseline.

What research is being done?

The National Eye Institute (NEI) is the Federal government's lead agency for vision research. The NEI is supporting a number of research studies both in the laboratory and with patients to learn more about the cause of AMD. This research should provide better ways to detect, treat, and prevent vision loss in people with the disease.

There is some suggestion that certain vitamins and minerals may play a role in the treatment of AMD. This treatment needs much more research before scientists can know for sure if it is helpful. The NEI has recently released the results of the Age-Related Eye Disease Study. This study demonstrated a significant benefit for vitamin and mineral supplements at certain high concentrations in a subgroup of patients with macular degeneration. A new formula is currently being tested and UAMS is the only NEI-designated center in Arkansas. For more information, please ask your doctor.

Scientists have begun to study the possibility of transplanting healthy cells into a diseased retina. Although this work is at a very early stage and still experimental, someday it may help people keep their vision or restore some lost vision.

What can you do to protect your vision?

Dry AMD. If you have dry AMD, you should have your eyes examined through dilated pupils at least once a year. This will allow your eye care professional to monitor your condition and check for other eye diseases as well.

You should also obtain an Amsler grid from an eye care professional to use at home. This will provide you with a quick and inexpensive test to evaluate your vision each day for signs of wet AMD. It works best for people who still have good central vision. You should check each eye separately--cover one eye and look at the grid, then cover your other eye and look at the grid. You also may want to check your vision by reading the newspaper, watching television, and just looking at people's faces. If you detect any changes, you should have an eye exam.
Wet AMD. If you have wet AMD, it is important not to delay treatment if your eye care professional advises you to have it. After treatment, you will need to have frequent eye examinations to detect any recurrence of leaking blood vessels. Studies show that people who smoke have a greater risk of recurrence than those who don't.

In addition, you should continue to check your vision (at home with the Amsler grid or other methods) as described under dry AMD and schedule an eye exam immediately if you detect any changes.

What can you do if you have already lost vision to AMD?

Normal use of your eyes will not cause further damage to your vision. Even if you have lost sight to AMD, you should not be afraid to use your eyes for reading, watching TV, and other usual activities.

Low vision aids are available to help you make the most of your remaining vision. Low vision aids are special lenses or electronic systems that make images appear larger. If you need low vision aids, your eye care professional can often prescribe them or refer you to a low vision specialist. In addition, groups and agencies that offer information about counseling, training, and other special services are available.

For more information about low vision programs, contact:

American Foundation for the Blind
11 Penn Plaza, Suite 300
New York, NY 10001
1-800-232-5463
212-502-7600
afbinfo@afb.org
http://www.afb.org

Council of Citizens with Low Vision International
1155 15th Street, NW, Suite 1004
Washington, DC 20005
1-800-733-2258
317-254-1332
http://www.cclvi.org

Lighthouse International
111 E. 59th Street New York, NY 10022
1-800-829-0500
212-281-9200
http://www.lighthouse.org

National Federation of the Blind
1800 Johnson Street Baltimore, MD 21230
301-659-9314
http://www.nfb.org

For more information about AMD, contact:

American Academy of Ophthalmology
655 Beach Street, P.O. Box 7424
San Francisco, CA 94109-7424
415-561-8500
http://www.eyenet.org

American Optometric Association
243 Lindbergh Boulevard
St. Louis, MO 63141
314-991-4100
http://www.aoanet.org

Association for Macular Diseases
210 E. 64th Street
New York, NY 10021
212-605-3719

(The) Foundation Fighting Blindness
Executive Plaza 1, Suite 800
11350 McCormick Road
Hunt Valley, MD 21031-1014
1-800-683-5555
410-785-1414
http://www.blindness.org

Macular Degeneration International
6700 North Oracle Road, Suite 121
Tucson, AZ 85704
1-800-393-7634
520-797-2525

National Eye Institute
2020 Vision Place Bethesda, MD 20892-3655
301-496-5248
http://www.nei.nih.gov

Prevent Blindness America
500 East Remington Road Schamburg, IL 60173
1-800-331-2020
847-843-2020
http://www.prevent-blindness.org

Ammar N. Safar, MD
Assistant professor
Director, Vitreo-Retinal Service
Department of Ophthalmology
501-686-5822 (appointments)
501-686-7000 (after hours emergencies)
Email: retina@uams.edu