What Is Macular Degeneration?

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Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is the leading cause of vision loss in people over the age of 60. The disease affects the retina, the paper-thin tissue lining the back of the eye.

In the very center of the retina is the macula, which contains the highest concentration of light-sensitive cells, called cones.

• Cones provide sharp, detailed, central vision used in activities like driving and reading.
• In macular degeneration, cells in the macular region begin to die, causing blind spots and distorted central vision.

The two types of macular degeneration are dry and wet.

• People can develop both types of the disease.
• The disease can affect one or both eyes.
• The disease may progress slowly or rapidly.

Dry macular degeneration may advance and cause vision loss with or without turning into the wet type of the disease. However, not everyone with early AMD will develop the advanced form of the disease.

Glossary of Terms

Age-Related Macular Degeneration: (AMD): A common eye disease that causes deterioration of the macula, the central area of the retina.

Bruch's membrane: Located in the retina between the choroid and retinal pigmented epithelium (RPE) layer; provides support to the retina and functions as the 'basement' membrane of the RPE layer.

Choroid: Layer of the eye behind the retina; contains blood vessels that nourish the retina.

Cones: The photoreceptor nerve cells present in the macula and concentrated in the fovea (the very center of the macula); enable people to see fine detail and color.

Dry Age-Related Macular Degeneration: The most common type of macular degeneration, about 85 to 90 percent of cases, occurs when the photosensitive cells of the macula slowly break down.

Drusen: Deposits of yellowish extracellular waste products that accumulate within and beneath the retinal pigmented epithelium (RPE) layer.

Fovea: The pit or depression at the center of the macula that provides greatest visual acuity.

Macula: The portion of the eye at the center of the retina that processes sharp, clear, straight-ahead vision.

Photoreceptors: The light sensing nerve cells (rods and cones) located in the retina.

Retina: The light sensitive layer of tissue that lines the back of the eye.

Retinal Pigmented Epithelium (RPE): A layer of cells that protects and nourishes the retina, removes waste products, prevents new blood vessel growth into the retinal layer and absorbs light not absorbed by the photoreceptor cells; these actions prevent the scattering of the light and enhance clarity of vision.

Rods: Photoreceptor nerve cells in the eyes that are sensitive to low light levels and are present in the retina, but outside the macula.

Sclera: The tough outer coat that protects the entire eyeball.

Wet Age-Related Macular Degeneration: A less common form of macular degeneration that occurs when abnormal blood vessels grow behind the macula as retinal pigment epithelial cells (RPE) and photoreceptor cells die. This form of the the disease accounts for approximately 10 percent of the cases of age-related macular degeneration, but results in 90 percent of the cases of legal blindness.

Resources

• Macular Degeneration Toolkit (Helpful Information to Understand and Manage Macular Degeneration)
• Expert Information on Macular Degeneration (Articles)
• Macular Degeneration Facts and Data (Fact Sheets)
• The Function of the Normal Macula (Infographic)

Illustration by Bob Morreale, provided courtesy of BrightFocus Foundation.