Macular Degeneration

Age-Related Macular Degeneration (AMD) is a common eye disease associated with aging that gradually destroys central vision. Central vision is needed for seeing objects clearly and for common daily tasks such as driving and reading. In some people, AMD advances so slowly that it will have little effect on their vision as they age. But in others, the disease progresses faster and may lead to a loss of vision in one or both eyes.

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.

AMD occurs in two forms:

Dry AMD affects about 90 percent of those with the disease. In dry AMD the macula is slowly damaged by changes in the function of some of the cells. As the macula gets damaged, central vision may be affected. The vision loss from dry AMD is usually mild but can be more severe depending on the amount of damage occurring.
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 into 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. Wet 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.

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 fifties 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 increases 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.

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.

People with dry AMD in one eye often do not notice any changes in their vision. With one eye seeing clearly, they can still drive, read, and see fine details. Some people may notice changes in their vision only if AMD affects both of their eyes.

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.

What can you do to protect your vision?

Dry AMD

If you have dry AMD, you should have your eyes examined with dilation 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. It works best for people who still have good central vision. This will provide you with a quick and inexpensive test to evaluate your vision each day for signs of wet AMD. An Amsler grid is a special grid pattern with a central dot. Test each eye separately--cover one eye and look at the center dot on the grid, and without looking around at the grid, notice if there are any wavy lines or areas missing from the grid pattern. Then cover your other eye and look at the center dot on the grid the same way. If you detect any changes in the normal pattern of the grid, you should have a dilated eye examination as soon as possible. It is also a good idea to check the vision in each eye separately by reading the newspaper, watching television, and just looking at people's faces.

Most eye care professionals also recommend multivitamins with specific dosages for certain vitamins. Several vitamins and minerals have been shown to slow the progression of the disease for those who have AMD. Ask your eye doctor for recommendations.

Wet AMD

If you have wet AMD, it is important not to delay laser surgery if your eye care professional advises you to have it. After surgery, 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.

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