Macular Degeneration

Definition

Macular degeneration is an eye disorder that damages the center of the retina, which is called the macula. This makes it difficult to see fine details.

Alternative Names

Age-related macular degeneration (ARMD), AMD. Senile macular degeneration (SMD) is an older name that is no longer in common use.

Causes, incidence, and risk factors

The retina is the layer of tissue at the back of the inner eye. It changes light and images that enter the eye into nerve signals that are sent to the brain. The macula is the part of the retina that makes our vision sharper and more detailed.

Macular degeneration is caused by damage to the area around blood vessels that supply the macula. This change in the blood vessels damages the macula.

Two phases of macular degeneration (AMD) exist:

• Dry macular degeneration occurs when the blood vessels under the macula become thin and brittle. Small yellow deposits, called drusen, form under the macula. As these drusen increase in size and number, they create a blurred and dim spot in the central vision of the eye. Almost all people with macular degeneration start with the dry form.
• Wet macular degeneration occurs in only about 10% of people with macular degeneration. Brittle vessels break down and new abnormal and very fragile blood vessels grow under the macula. This is called choroidal neovascularization. These vessels leak blood and fluid, which leads to damage of the macula. Although only about 10 percent of people with macular degeneration have this form, it causes most of the vision loss associated with the condition.

Scientists aren’t sure what causes AMD. The disease is most common in people over 60, which is why it is often referred to as age-related macular degeneration.

In addition to heredity, other risk factors are:

• Caucasian race
• Cigarette smoking
• High-fat diet
• Female gender
• Obesity

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Reviewer Info: Edward B. Feinberg, MD, MPH, Professor and Chair Emeritus, Department of Ophthalmology, Boston University School of Medicine, Boston, MA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.; ADAM Health Illustrated Encyclopedia, 08/16/2009

This feature is for informational purposes only and should not be used to replace the care and information received from your healthcare provider. Please consult a healthcare professional with any health concerns you may have.