Adult Macular Degeneration (AMD)

by Heather S. Oliff, PhD

Definition

The retina is the tissue that lines the back of the eye. It sends visual signals to the brain. The macula is part of the retina. It is responsible for central vision. Macular degeneration is decline of the macula. It causes a gradual loss of sharp, central vision. The condition is mainly a disease of aging. In rare cases it can occur in younger people.

Macular Degeneration

Adult (or age-related) macular degeneration (AMD) occurs in two forms:

Dry AMD

About 90% of all people with AMD have this type.
An area of the retina becomes diseased. This leads to a slow breakdown of cells in the macula. The central vision is a gradually lost.

Wet AMD

Only about 10% of people with AMD have this type. It accounts for the majority of all blindness from the disease.
As dry AMD worsens, new blood vessels may begin to grow. These new blood vessels often leak blood and fluid under the macula. This can lead to permanent damage of the macular region.

Causes

The cause of AMD is not known.

Risk Factors

Factors that increase your risk for MD include:

Age: risk increases with age, most commonly seen in senior citizens
Family members with AMD
Race: White
Smoking
Sex: women at possible increased risk
Cardiovascular risks: high blood pressure, high cholesterol

Symptoms

In some people, AMD advances very slowly. It has little effect on their vision. In others, the disease progresses faster. It may lead to significant vision loss. Both dry and wet AMD cause no pain.

Symptoms include:

Blurred vision
Difficulty seeing details in front of you, such as faces or words in a book
Blurred vision that goes away in brighter light
A small, but growing blind spot in the middle of the field of vision
Straight lines, such as door frames, appear crooked or distorted

Diagnosis

The doctor will ask about your symptoms and medical history. A physical exam will be done. The doctor may suspect AMD if you are older and have had recent changes in your central vision. A specialist will look for signs of the disease. They will use eye drops to dilate (enlarge) your pupils. This will allow them to view the back of the eye.

You may also be asked to view an Amsler grid. This is a pattern that looks like a checkerboard. Changes in your central vision will cause the grid to appear distorted. This is a sign of AMD.

Treatment

Treatment may include:

Dry AMD

Research has shown that certain high-dose vitamins and minerals may slow the progression of the disease in some people.

Wet AMD

This procedure is used in some cases of wet AMD. A strong laser light beam is aimed onto the new blood vessels. The beam will destroy the vessels. It usually takes less than 30 minutes to complete. You may need additional laser treatments. This treatment is used less often since the development of newer treatments.

This procedure is a type of treatment that involves injecting a light-sensitive dye into the blood. The affected areas in the back of the eye are then hit with a special laser light. The light activates the dye to destroy certain blood vessels. It also takes less than 30 minutes. You may need to have additional treatments.

Another way to treat wet AMD is an injection of a special medication. It is called a vascular endothelial growth factor (VEGF) inhibitor. The medicine is injected into the vitreous (fluid) in the back of the eye. This method is quickly growing in popularity. It usually needs to be repeated multiple times. In rare cases, it may need to be given indefinitely.

About 1/3 of patients will show significant improvement in vision. This is the first treatments to show improved vision in a significant number of patients.

Prevention

There are no guidelines for preventing AMD.

For overall eye health:

You should have a comprehensive exam of your eyes regularly. The exam should include dilation to look at the retina closely.
Don't smoke.
Consider taking a multivitamin with antioxidants every day.
Consider omega-3 fatty acid supplements.

If you have AMD, your doctor may advise you to monitor for problems by using an Amsler grid at home. Your ophthalmologist should discuss the various treatment options with you.