Age-related macular degeneration (AMD) is an eye disease that destroys central vision. It damages the macula, a small area at the back of the eyeball. The macula provides color and the fine detail needed for central vision.

You need central vision for activities like reading, driving, and recognizing faces. Because AMD does not affect side vision, it does not lead to complete blindness. The risk of getting AMD increases as you get older, starting at age 50.

There are two types of age-related macular degeneration. Either type may affect just one eye, but if one eye has AMD, then the other eye may eventually get it as well.

    * Dry AMD is the most common form (90% of cases). It develops slowly and does not usually cause severe vision loss. In dry AMD, cells and blood vessels beneath the macula break down and cause deposits in the back of the eye called drusen. This damages the macula and affects its ability to send signals to the brain. Central vision slowly becomes dimmer or more blurry over time.

    * Wet AMD is much less common (10% of cases). It can cause permanent damage to the macula over months or even weeks. Wet AMD often happens where dry AMD exists. Abnormal, fragile blood vessels grow in the back of the eye. These blood vessels leak, causing the macula to break down. They also move the macula from its normal place at the back of the eye, distorting central vision.

What causes AMD?

Damage to the nerve cells in the macula causes vision loss in both wet and dry AMD. The process that leads to this damage is different for each type of AMD. However, both conditions may be related to the breakdown of cells that supply the macula with blood and nutrients. Experts are still studying the causes of both conditions, but they know several different things may play a part in getting either type of AMD. These include:

    * Genetics (traits you are born with)
    * Nutrition
    * Smoking
    * Damage caused by sunlight

What are the symptoms?

The main symptom of macular degeneration is dim or fuzzy central vision. Objects may appear distorted or smaller than they really are. You may develop a blank or blind spot or distortion in your central field of vision. As AMD progresses, you may find that you have trouble with tasks like reading or driving.

Dry AMD symptoms develop so gradually that you may not notice them, but wet AMD symptoms can develop in a period of weeks or months. With wet AMD, straight lines may appear wavy or curved.

Wet AMD symptoms tend to appear suddenly and get worse rapidly. Vision changes and loss are usually quite severe. If you think you might have wet AMD, see your health professional right away. In some cases, quick treatment may help you maintain your central vision.

People sometimes confuse age-related macular degeneration (AMD) with a condition called presbyopia, which is a normal part of aging that affects nearly all people as they get older. Most people older than 45 find it increasingly difficult to focus on close objects (presbyopia), but glasses can usually improve your ability to see close objects.

How is AMD diagnosed?

A doctor can usually detect AMD by doing a regular eye exam and asking questions about your medical history. Tests may include a vision test and an ophthalmoscopy, which allows the doctor to see inside your eye. If you have AMD, your eye doctor may see drusen, which are spots of cellular waste material that form at the back of the eye.

The doctor may also have you look at an Amsler grid, which is a chart with lines and a dot at the center that can help detect changes in your central vision. If you have changes, the image will be distorted.