What is Macular Degeneration?

Macular degeneration is a disorder that includes a variety of eye diseases that affect central vision. Central vision is what you see directly in front of you rather than what you see at the side (or periphery) of your vision.

Macular degeneration is caused when part of the retina deteriorates. The retina is the interior layer of the eye. The macula is the central portion of the retina and is responsible for detailed vision.
Age-related macular degeneration is the most common type of macular degeneration and is the leading cause of legal blindness in people older than 55 years in the United States. The disease affects more than 10 million Americans, including 23% of Americans older than 90 years. Because overall life expectancy continues to increase, age-related macular degeneration has become a major public health problem.

There are 2 types of age-related macular degeneration:

Dry (atrophic) form: Multiple, small, round, yellow-white spots called drusen are the key identifiers for the dry type. The spots are located in the back of the eye at the level of the outer retina. Spots typically become visible when a person reaches his or her late 30s or older. People with these spots may have excellent vision and no symptoms. Most people with age-related macular degeneration begin with the dry form. Wet (exudative) form: In the wet form, newly created abnormal blood vessels grow under the center of the retina. These blood vessels leak, bleed, and scar the retina, distorting vision or destroying central vision. Vision distortion usually starts in one eye and may affect the other eye later.

Macular Degeneration Causes No one knows the causes of age-related macular degeneration. Causes are likely to be genetically inherited, but environmental factors also contribute. Macular degeneration often runs in families. A recent study of twins showed that genetic factors play a significant role in the cause. Many of the following risk factors have been found to be associated with age-related macular degeneration: Age: The likelihood to develop macular degeneration increases with age. Race: Macular degeneration is more common in whites but occurs in all races. Smoking High blood pressure Vascular disease High intake of saturated fat and cholesterol High blood cholesterol level Farsightedness (hyperopia) Exposure to sunlight Family history TOP OF PAGE

Macular Degeneration Symptoms

When to Seek Medical Care

For age-related macular degeneration, you should see an Ophthalmologist (a medical doctor who specializes in eye care and surgery).

In general, people older than 45 years should have a complete eye examination and then follow-up examinations every 2-4 years.

People with age-related macular degeneration should check their vision daily and promptly notify their Ophthalmologist of any changes in their vision.

It is very rare that a person goes to a hospital for macular degeneration problems. Because of the specialized nature of eye examination equipment, macular degeneration problems are usually handled best in the Ophthalmologist's office.

If you notice a sudden decrease in vision in one or both of your eyes and you cannot reach your Ophthalmologist, then go to the hospital's emergency department. Timely treatment of early wet age-related macular degeneration can prevent further visual loss.

Visual symptoms and/or eye pain may not be symptoms of age-related macular degeneration. You may need prompt diagnosis and treatment of a different eye condition.

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Questions to Ask the Doctor

What can I do to decrease my chances of losing more vision? What low-vision aids are available to help me with my remaining vision? What symptoms should I watch for? What lifestyle changes should I make? What treatment options are available for my condition?

Exams and Tests

Initial tests include measurement of the sharpness of vision and an examination of the retina. During the examination of the retina, the Ophthalmologist looks for specific signs of macular degeneration.

Multiple spots in the macular region become the hallmark of the dry form of age-related macular degeneration. These spots are accumulations of fat and cellular debris under the pigmented outer layer of the retina. They appear as white to yellow dots that will merge together with time. The spots may cause mild to moderate loss of central vision.

Another sign of age-related macular degeneration is degeneration of the pigmented layer itself. Degeneration appears as thinning and loss of the retina, the pigment layer, and the choroid, one of the outer layers of the eyeball. Loss of vision tends to be moderate. It causes blind spots (called scotomas) next to central vision. If degeneration of the pigment layer affects the center of the macula, a person can lose vision.

In eyes that become complicated by the wet form of age-related macular degeneration, fluid, blood, scarring, and new blood vessel membranes below the retina might be seen. These abnormalities may progress rapidly over days to months. Eventually, they may result in profound irreversible central vision loss. Wet age-related macular degeneration reduces vision sharpness to 20/200 or worse within 2 years in 70% of affected eyes.

If signs of macular degeneration are found, an Ophthalmologist may take detailed pictures of the retina for future comparison. Tests may also include:

Fluorescein angiography: A special dye is injected into the arm. Then, an Ophthalmologist photographs the retina as the dye passes through the retina. This test determines if laser treatment is necessary and, if so, the location of the treatment.

Indocyanine green angiography: This test uses infrared wavelengths to view the retina. The test may help to identify signs of macular degeneration that cannot be seen with fluorescein angiography.

Optical Coherence Tomography (OCT): This represents a noninvasive examination technique that produces a cross-sectional image of the posterior retina in vivo. Although this method is now widely applied in the diagnosis of various macular disorders, its role in evaluation and follow-up of patients with age-related macular degeneration is not well established.

Microperimetry using the Rodenstock scanning laser ophthalmoscope: This is used to quantify macular sensitivity and fixation pattern.

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