Macular Degeneration

Causes Blurred Vision and Possibly Legal Blindness

Age-related macular degeneration (AMD) is damage or breakdown of the macula. The macula is a small area at the back of the eye that allows us to see fine detail clearly. When the macula doesn’t function correctly, we experience blurriness or darkness in the center of our vision. Age related macular degeneration affects both distance and close vision, and can make some activities like threading a needle or reading very difficult or totally impossible.

When the macula is damaged it results in extreme loss of central vision. Since the peripheral retina is not involved macular degeneration does not lead to complete blindness.

The risk of AMD significantly increases with age. In fact, people between ages 64 and 74 have a one in four chance of developing the disease. Over the age of 75, the chances increase to one in three. Many seniors already have AMD and don’t even know it.

A visit to your eye doctor is the greatest defense in helping to preserve your vision.

AMD can also occur during middle age. Other risk factors include:

Gender-- Women tend to be at greater risk for AMD than men.
Race-- Whites are much more likely to lose vision from AMD than Blacks.
Smoking-- Smoking may increase the risk of AMD.
Obesity —Research studies suggest a link between obesity and the progression of early and intermediate stages of AMD to advanced stages.
Family History-- Those with immediate family members who have AMD are at a higher risk of developing the disease.
Sunlight— Cumulative exposure to ultraviolet light may contribute to a higher risk of AMD.

There are two forms of this disease.

• Dry AMD-- Ninety percent of all people with AMD have this type. Scientists are still not sure what causes dry AMD. Studies suggest that an area of the retina becomes diseased, leading to the slow breakdown of the light-sensing cells in the macula and a gradual loss of central vision.
• Wet AMD-- Although only 10 percent of all people with AMD have this type, it accounts for 90 percent of all blindness from the disease. As dry AMD worsens, new blood vessels may begin to grow and cause "wet" AMD. 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.

How is AMD detected?

Since macular degeneration is painless and can cause very subtle changes in vision, getting regular comprehensive eye exams from your eye care professional is the only way it can be diagnosed. Your eye care professional may suspect AMD if you are over age 60 and have had recent changes in your central vision. To look for signs of the disease, he or she will use eye drops to dilate, or enlarge, your pupils. Dilating the pupils allows your eye care professional to view the back of the eye better. You may also be asked to view an Amsler grid, a pattern that looks like a checkerboard. Early changes in your central vision will cause the grid to appear distorted, a sign of AMD.

Do NOT depend on the grid displayed below for any diagnoses.

While covering one eye, look at dot in center of grid. If lines around dot are wavy or distorted, you should see your eye care professional.

Example of advanced AMD

Other diagnostic tests may include an OCT or Talia RTA to evaluate the health of the macular area or a central or macular visual field test. If your eye care professional believes you need treatment for wet AMD, he or she may suggest a fluorescein angiogram. In this test, a special dye is injected into your arm. Pictures are taken as the dye passes through the blood vessels in your retina. The test allows your eye care professional to identify any leaking blood vessels and recommend treatment.

How is dry AMD treated?

Once dry AMD reaches the advanced stage, no form of treatment can prevent vision loss. However, treatment can delay and possibly prevent intermediate AMD from progressing to the advanced stage, in which vision loss occurs. The National Eye Institute's Age-Related Eye Disease Study (AREDS) found that taking a specific high-dose formulation of antioxidants and zinc significantly reduces the risk of advanced AMD and its associated vision loss. Slowing AMD's progression from the intermediate stage to the advanced stage will save the vision of many people.

How is wet AMD treated?

There are two treatments for wet AMD: laser surgery and photodynamic therapy. Neither treatment is a cure for wet AMD. Each treatment may slow the rate of vision decline or stop further vision loss. The disease and loss of vision may progress despite treatment.

• Laser surgery. This procedure uses a laser to destroy the fragile, leaky blood vessels. A high energy beam of light is aimed directly onto the new blood vessels and destroys them, preventing further loss of vision. However, laser treatment also may destroy some surrounding healthy tissue and some vision. Only a small percentage of people with wet AMD can be treated with laser surgery. Laser surgery is more effective if the leaky blood vessels have developed away from the fovea, the central part of the macula. (See illustration at the beginning of this document.) Laser surgery is performed in a doctor's office or eye clinic.

The risk of new blood vessels developing after laser treatment is high. Repeated treatments may be necessary. In some cases, vision loss may progress despite repeated treatments.

• Photodynamic therapy. A drug called verteporfin is injected into your arm. It travels throughout the body, including the new blood vessels in your eye. The drug tends to "stick" to the surface of new blood vessels. Next, a light is shined into your eye for about 90 seconds. The light activates the drug. The activated drug destroys the new blood vessels and leads to a slower rate of vision decline. Unlike laser surgery, this drug does not destroy surrounding healthy tissue. Because the drug is activated by light, you must avoid exposing your skin or eyes to direct sunlight or bright indoor light for five days after treatment. Photodynamic therapy is relatively painless. It takes about 20 minutes and can be performed in a doctor's office.

Photodynamic therapy slows the rate of vision loss. It does not stop vision loss or restore vision in eyes already damaged by advanced AMD. Treatment results often are temporary. You may need to be treated again.

New research shows a specific gene that increases the risk of Macular Degeneration. Click on the link below to learn more.

 http://www.nei.nih.gov/news/statements/genes_amd.asp