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Eye Disease: Macular Degeneration

What is Age-Related Macular Degeneration?

Macular degeneration is one of the leading causes of decreased vision in the United States. It is a slowly progressive disease with a highly variable and unpredictable course. Most cases (80%) are sporadic (not hereditary) and only 20% seem to occur in family clusters. People with AMD do not go completely blind but get blurred central vision. When the disease is advanced, a person may not be able to read, see faces, drive or see the TV well, but they can live independently and do most daily tasks.

Macular degeneration is a disease of the retina. The retina is a layer of nerve tissue that lines the back of the eye upon which light is focused. It is analogous to the film in a camera. The retina converts light into signals which are sent to the brain where vision is perceived. The central portion of the retina is called the macula and is responsible for our sharpest central (reading) vision. In age-related macular degeneration, or AMD, sight-threatening changes occur in the macula. These changes occur only rarely in people under 50 and most commonly occur in people over age 60. In fact, up to 30% of white people over the age of 70 have evidence of AMD. The disease rarely occurs in people of other races. The degenerative changes that occur fall into two categories, "wet" and "dry".

"Dry" signs of AMD include the accumulation of drusen (tiny yellow-white lumps on the under-surface of the retina), loss of cells in the macula, and deterioration of the pigmented cells under the retina. Of the people with AMD, 80% to 95% have the "dry" type. Some individuals with "dry" AMD can have nearly normal sight, whereas others may notice distortion and blurring, while others may have significant loss of central vision. There currently is no known treatment to slow or stop the changes that occur with "dry" AMD, although sunglasses and vitamins may help.

The "wet" form of AMD is also known as the neovascular or exudative type. Between 5% and 20% of all people with AMD have this form, and they may experience a more rapid loss of vision. In the "wet" form, new blood vessels develop beneath the retina. This process is called choroidal neovascularization. Generally, the new blood vessels develop at the outer edges of the macula and extend in toward the fovea. These vessels leak fluid and bleed under the retina. This causes deterioration of the retinal cells and loss of vision. Ultimately, scarring occurs, which may leave permanent loss of central vision. Fortunately, side or peripheral vision is rarely affected.

What are the Symptoms?

Typical symptoms include distortion of vision (straight lines or objects appear wavy or crooked), a dark spot in the central vision, or blurred vision. Later, there is a loss of reading vision. It can be difficult to drive, watch TV, or recognize the features on a friend's face. Residual peripheral vision permits patients to see large objects and navigate through their environment.

If you believe you might suffer from Macular Degeneration, be sure to contact us or make an appointment soon.

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