Macular Degeneration

Age-related macular degeneration (AMD) is a condition that affects the macula, the part of the retina responsible for sharp, detailed central vision. AMD can make everyday activities like reading, recognizing faces, or driving more difficult.

AMD usually develops with age and often progresses gradually. It does not cause pain, and some people may not notice changes in their vision at first. AMD can affect one or both eyes and is generally divided into two forms: dry AMD and wet AMD.

Wet AMD occurs when abnormal blood vessels grow beneath the retina and leak blood or fluid into the macula. This can damage the macula and cause central vision to change more quickly than with dry AMD.

One warning sign is that straight lines may suddenly look wavy or distorted. You may also notice a new blurry or dark spot in the center of your vision.

If you notice a sudden change in your vision or straight lines begin to look wavy, contact your eye care professional promptly. Wet AMD can often be treated, and early treatment is important.

Dry AMD is the more common form of AMD. It develops when the macula gradually changes and becomes less able to function normally. Vision changes are usually gradual, although the amount of vision loss can vary from person to person.

You may notice blurred or less detailed central vision, difficulty recognizing faces, or needing brighter light to read. One of the common signs of AMD is drusen, which are small yellow deposits that can develop beneath the retina. Having certain types or larger amounts of drusen can increase the risk of AMD progressing.

Drusen are yellow deposits under the retina. They often are found in people over age 60. Your eye care professional can detect drusen during a comprehensive dilated eye exam.

Drusen alone do not usually cause vision loss. In fact, scientists are unclear about the connection between drusen and AMD. They do know that an increase in the size or number of drusen raises a person’s risk of developing either advanced dry AMD or wet AMD. These changes can cause serious vision loss.

Dry AMD has three stages, all of which may occur in one or both eyes:

• Early AMD: People with early AMD have either several small drusen or a few medium-sized drusen. At this stage, there are no symptoms and no vision loss.
• Intermediate AMD: People with intermediate AMD have either many medium-sized drusen or one or more large drusen. Some people see a blurred spot in the center of their vision. More light may be needed for reading and other tasks.
• Advanced Dry AMD: In addition to drusen, people with advanced dry AMD have a breakdown of light-sensitive cells and supporting tissue in the central retinal area. This breakdown can cause a blurred spot in the center of your vision. Over time, the blurred spot may get bigger and darker, taking more of your central vision. You may have difficulty reading or recognizing faces until they are very close to you.

If you have vision loss from dry AMD in one eye only, you may not notice any changes in your overall vision. With the other eye seeing clearly, you still can drive, read, and see fine details. You may notice changes in your vision only if AMD affects both eyes. If blurriness occurs in your vision, call Southern Eye Associates to schedule an appointment for a comprehensive dilated eye exam.

Ninety percent of all people with AMD have this type. Scientists are still not sure what causes dry AMD.

Dry AMD is much more common than wet AMD. Most people with AMD have the dry form.

Wet AMD, however, is responsible for a large share of the severe vision loss associated with advanced AMD. That is why it is important to monitor AMD and report new changes in your vision promptly. Straight lines that suddenly look wavy, new distortion, or a new blurry or dark spot in your central vision can be warning signs of wet AMD and should be evaluated by an eye care professional.

Dry AMD and wet AMD are different forms of the disease, and some people with dry AMD can develop wet AMD. This is one reason regular monitoring is important, particularly for people with intermediate or advanced AMD.

If you notice a sudden change in your central vision, new distortion, or straight lines appearing wavy, contact your eye care professional promptly.

Age is the biggest risk factor for AMD. Your risk may also be higher if you have a family history of AMD or certain other risk factors. For instance, a large study found that people in middle-age have about a 2 percent risk of getting AMD, but this risk increased to nearly 30 percent in those over age 75.

Other risk factors include:

• Smoking: Smoking may increase the risk of AMD.
• Obesity: Research studies suggest a link between obesity and the progression of early and intermediate stage AMD to advanced AMD.
• Race: AMD is more common among white people than African American people.
• Family history: Those with immediate family members who have AMD are at a higher risk of developing the disease.
• Gender: Women appear to be at greater risk than men.

Wet AMD can be treated with laser surgery, photodynamic therapy, and injections into the eye. None of these treatments is a cure for wet AMD. 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. 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 the 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.
• Injections: Wet AMD can now be treated with new drugs that are injected into the eye (anti-VEGF therapy). Abnormally high levels of a specific growth factor occur in eyes with wet AMD and promote the growth of abnormal new blood vessels. This drug treatment blocks the effects of the growth factor.

You will need multiple injections that may be given as often as monthly. The eye is numbed before each injection. After the injection, you will remain in the doctor’s office for a while and your eye will be monitored. This drug treatment can help slow down vision loss from AMD and in some cases improve sight.

Once dry AMD reaches the advanced stage, no form of treatment can prevent vision loss. However, treatment can delay and possibly prevent intermediate ADM 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.