Age-related Macular Degeneration

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Perhaps you have just learned that you or a loved one has age-related macular degeneration, also known as AMD. If you are like many people, you probably do not know a lot about the condition or understand what is going on inside your eyes.  This page will give you a general overview of AMD. The aim is to answer your questions and to help relieve some of the anxiety you may be feeling

What is AMD?

AMD is a common eye condition among people age 50 and older. It is a leading cause of vision loss in older adults. It gradually destroys the macula, the part of the eye that provides sharp, central vision needed for seeing objects clearly.  In some people, AMD advances so slowly that vision loss does not occur for a long time. In others, the disorder progresses faster and may lead to a loss of vision in one or both eyes. The vision loss makes it difficult to recognize faces, drive a car, read, print, or do close work, such as sewing or fixing things around the house.

Despite the limited vision, AMD does not cause complete blindness. You will be able to see using your side (peripheral) vision.

The Macula

The macula is made up of millions of light-sensing cells that provide sharp, detailed central vision. It is the most sensitive part of the retina, which is located at the back of the eye. The retina quickly turns light into electrical signals and then sends these electrical signals to the brain through the optic nerve. Next, the brain translates the electrical signals into images we see. If the macula is damaged, fine points in these images are not clear. The picture is there, but the fine points are lost.
Who is at risk?

AMD usually occurs in people who are age 50 and older. As people get older, the risk increases. Other risk factors include the following:

Smoking – Research shows that smoking increases the risk of AMD two-fold.
Race – Caucasians are much more likely to get AMD than people of African descent.
Family history – People with a family history of AMD are at higher risk.

Does lifestyle make a difference?

Some lifestyle choices, like smoking, are linked to AMD although it remains unknown if altering any of these would alter the impact of AMD on an individual. Nevertheless, the following choices may have an impact on AMD and certainly promote healthy living, including the following:

  • Avoiding smoking
  • Exercising
  • Maintaining normal blood pressure and cholesterol levels
  • Eating a healthy diet rich in green, leafy vegetables and fish

What are the forms of AMD that can cause vision loss?

There are two forms of AMD: dry and wet. Either form can advance and cause severe vision loss. Later sections of this booklet describe the different types in greater detail.

The following is a brief description of each:

  • The dry form is more common and has three stages-early, intermediate, and advanced. It happens when the light-sensitive cells in the macula slowly break down, gradually blurring central vision in the affected eye.
  • The wet form is considered advanced AMD and can be more severe. It happens when new blood vessels under the macula leak blood and fluid. Damage to the macula can occur rapidly.

All people who have the wet form had the dry form first.

Dry AMD

What is Dry AMD?

Dry AMD is the most common form of AMD in its early or intermediate stages. It occurs in about 90 percent of the people with the condition.

Dry AMD happens when the light-sensitive cells in the macula slowly break down, gradually blurring central vision in the affected eye. As dry AMD progresses, you may see a blurred spot in the center of your vision. Your eye care professional may call this “geographic atrophy.”

Over time, central vision in the affected eye can be slowly lost as less of the macula works.

What are the symptoms?

Dry AMD has few symptoms in the early stages. It is important to have your eyes examined regularly before the disease progresses.

In the later stages, blurred vision is the most common symptom of dry AMD. Objects also may not appear to be as bright as they used to be.

As a result, you may have trouble recognizing faces. You may need more light for reading and doing other tasks. Both eyes can have dry AMD or one eye can be affected first.

What are drusen?

Drusen are another early sign of dry AMD. They are yellow deposits under the retina. They can be small or large in size.

Your eye care professional can see drusen when he or she examines the retina during a comprehensive dilated eye exam.

Drusen alone do not usually cause vision loss. But people with large drusen are at risk of developing a more severe form of AMD, which results in severe vision loss.

Dry AMD has three stages, all occurring in one or both eyes.

These stages are defined in part by the size and number of drusen under the retina:

Early AMD. People with early AMD have either small drusen or a few medium-sized drusen. At this stage, you may not have any symptoms or vision loss.
Intermediate AMD. People with this stage of AMD have either many medium-sized drusen or one or more large drusen. Many people will have no symptoms, so don’t wait for symptoms to determine if you have an intermediate stage of AMD. Some people see a blurred spot in the center of their vision. They often need more light to read and to do other tasks.
Advanced dry A

Vision loss and dry AMD

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 if dry AMD affects both eyes or if you develop the wet form of the disease. In any case, see an eye care professional for a comprehensive dilated eye exam if blurring occurs in your vision.
Can the dry form turn into the wet form?

All people who have the wet form had the intermediate stage of the dry form first. The dry form also can suddenly turn into the wet form, even during early stage AMD. Eye care professionals have no way to tell if the dry form will turn into the more severe wet form.

Dry AMD can turn into wet AMD at any time. You should get an Amsler grid from your eye care professional to check your vision for signs of wet AMD.

MD. In addition to drusen, people with advanced dry AMD have a breakdown of light-sensitive cells supporting tissue in the macula. This breakdown can cause a blurred spot in the center of your vision, often called geographic atrophy. Over time, the blurred spot may get bigger and dark, taking away a larger area of your straight-ahead vision.

 

Wet AMD

What is wet AMD?

Wet AMD affects about 10 percent of all people with AMD. This type, however, is more severe than the early and intermediate stages of the dry form.

Wet AMD happens when abnormal blood vessels behind the retina start to grow under the macula. These new blood vessels can be fragile and leak blood and fluid. The blood and fluid cause the macula to swell and damage occurs rapidly. The damage may also cause scarring of the retina.

Although loss of central vision can happen quickly, eye care professionals can slow down or stop the progression of wet AMD if it is detected before severe vision loss occurs.

What are the symptoms?

During the early stages of wet AMD straight lines may appear wavy. People with wet AMD also may develop a blind spot, which results in the loss of central vision.

If you notice these or other changes to your vision, contact your eye care professional at once. Again, eye care professionals may be able to treat the condition before severe vision loss occurs.

Treatment options for wet AMD

With early diagnosis and proper treatment, you can delay the progression of AMD. The earlier it is detected, the better your chances of keeping your vision. Wet AMD typically results in severe vision loss. However, eye care professionals can try different therapies to stop further vision loss. You should remember that the therapies described below are not a cure. The condition may progress even with treatment.

Injections. One option to slow the progression of wet AMD is to inject drugs into your eye. With wet AMD, abnormally high levels of vascular endothelial growth factor (VEGF) are secreted in your eyes. This substance promotes the growth of new abnormal blood vessels. The anti-VEGF injection therapy blocks its effects. If you get this treatment, you may need multiple injections. Your eye care professional may give them monthly. Before each injection, your eye care professional will numb your eye and clean it with antiseptics. To prevent the risk of infection, a doctor may prescribe antibiotic drops.

Photodynamic therapy. This technique involves laser treatment of select areas of the retina. First, a drug called verteporfin will be injected into a vein in your arm. The drug travels through the blood vessels in your body, including any new, abnormal blood vessels in your eye. Your eye care professional then shines a laser beam into your eye to activate the drug in the blood vessels. Once activated, the drug destroys the new blood vessels and slows the rate of vision loss. This procedure takes about 20 minutes.

Laser surgery Eye care professionals sometimes treat certain cases of wet AMD with laser surgery, though this is less common than other treatments. This treatment is performed in a doctor’s office or eye clinic. It involves aiming an intense beam of light at the new blood vessels in your eyes to destroy them. However, laser treatment also may destroy some surrounding healthy tissue and cause more blurred vision.

Advanced AMD

What is advanced AMD?

Both the wet form and the advanced dry form are considered advanced AMD. It can occur in the same eye or an eye may have just one form or the other. In most cases, only advanced AMD can cause vision loss.
Additional risk

People who have advanced AMD in one eye are at especially high risk of developing advanced AMD in the other eye.

However, research has shown that high doses of vitamins and mineral supplements may slow the progression of intermediate AMD to the more advanced stage.

*** Source – national eye Institute, with minor edits by Dr. Martin