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Adult Macular Degeneration (AMD)

Definition

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

Macular Degeneration

© 2008 Nucleus Medical Art, Inc.

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

Dry AMD

Ninety percent of all people with AMD have this type. An area of the retina becomes diseased, leading to the slow breakdown of cells in the macula. Central vision is a gradually lost.

Wet AMD

Although only 10% of all 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 and cause "wet" AMD. 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 adult macular degeneration is not known.

Risk Factors

A risk factor is something that increases your chance of getting a disease or condition.

Risk factors for AMD 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, macular degeneration advances so slowly that it has little effect on their vision. But in others, the disease progresses faster and 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

Diagnosis

The doctor will ask about your symptoms and medical history, and perform a physical exam. The doctor may suspect AMD if you are older and have had recent changes in your central vision. To look for signs of the disease, an ophthalmologist or optometrist will use eye drops to dilate (enlarge) your pupils to view the back of the eye.

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

Laser Photocoagulation

Laser photocoagulation is used in some cases of wet macular degeneration. A strong laser light beam is aimed onto the new blood vessels to destroy them. Done on an outpatient basis, treatment usually takes less than thirty minutes to complete. You may need additional laser treatments to manage macular degeneration and prevent further vision loss. This treatment is used less frequently since the development of newer treatments.

Photodynamic Therapy

Photodynamic therapy is a type of treatment that involves injecting a light-sensitive dye, called verteporfin, into the bloodstream. The affected areas in the back of the eye are then hit with a special laser light to activate the dye and destroy certain blood vessels. This procedure, which is also done on an outpatient basis, takes less than thirty minutes. As with laser photocoagulation, you may need to have additional treatments.

A recent review of three trials found that photodynamic therapy may reduce vision loss caused by macular degeneration. The most serious side effect was a severe decrease in visual acuity. This affected about 1 in 50 patients within a week of treatment. *

Vascular Endothelial Growth Factor Inhibitor

Another way to treat wet AMD is an injection of a special medication, 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, This treatment usually needs to be repeated multiple times and, in rare cases, indefinitely. Anti-VEGF injections are performed in an office by an ophthalmologist who has special training in retinal diseases.

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 adult macular degeneration because the cause is unknown. You should have a comprehensive examination of your eyes regularly, including dilation to examine the retina closely.

Don't smoke and consider taking a multivitamin with antioxidants every day. You may also 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.

RESOURCES:

American Macular Degeneration Foundation
http://www.macular.org

Macular Degeneration Foundation
http://www.eyesight.org

CANADIAN RESOURCES:

AMD Canada
http://www.amdcanada.com

The National Coalition for Vision Health
http://www.visionhealth.ca/

References:

Age-related macular degeneration. National Eye Institute website. Available at: http://www.nei.nih.gov/health/maculardegen/armd_facts.asp#1d .

Macular Degeneration Foundation website. Available at: http://www.eyesight.org .

National Eye Institute website. Available at: http://www.nei.nih.gov/ .

Photodynamic therapy: an emerging treatment for classically leaky neovascularizations. Macular Degeneration Foundation website. Available at: http://www.eyesight.org/Research/Research-Photodynamic/research-photodynamic.html .

Ranibizumab for neovascular age-related macular degeneration. N Engl J Med . 2006 Oct 5;355(14):1419-31.

11/1/2007 DynaMed's Systematic Literature Surveillance DynaMed's Systematic Literature Surveillance : Wormald R, Evans J, Smeeth L, Henshaw K. Photodynamic therapy for neovascular age-related macular degeneration. Cochrane Database of Systematic Reviews. 2007;(4). DOI: 10.1002/14651858.CD002030.pub3.



Last reviewed March 2008 by Alexander J. Anetakis, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.


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