Age-related macular degeneration, or more simply "macular degeneration," is the most common cause of permanent visual loss among the elderly in the United States. The disease is more prevalent among white persons, particularly those with light-colored eyes, and usually affects people over the age of 55 years. The tissue in the back of the eye is called the retina, which is the part of the eye that actually "sees." (The retina of the eye is similar to the film inside a camera.) The center of the retina is called the macula, which is the part of the eye that is used to focus on a visual target, such as when reading or threading a needle. Any disease of the macula will cause difficulties with central vision, but will not affect peripheral vision, or vision "out of the corner of the eye."

In its earliest stages, macular degeneration usually causes distortion of the central vision. Many patients notice that straight lines (such as telephone poles or doorframes) look wavy or bent. Other patients may notice a blank spot in the center of their vision that they try to "see around." Advanced macular degeneration causes more severe decreases in central vision, but does not affect peripheral vision. Therefore, macular degeneration does not cause complete blindness. The progression of macular degeneration can be followed by the use of an Amsler grid, which looks like a piece of graph paper. By looking at the grid with each eye separately, subtle distortions in the grid, such as waviness of the lines or blank spots, can often be detected early.

Broadly speaking, there are two different forms of macular degeneration. The more common form is called non-exudative or "dry," and is characterized by various aging changes of the macula. There is no treatment for "dry" macular degeneration, but this is usually a mild disease that only gradually (if ever) causes any significant changes in vision. The other form of the disease, called exudative or "wet," is less common but more severe. "Wet" macular degeneration is caused by new blood vessel growth underneath the macula. These blood vessels can leak (or exude) fluid and blood, which may cause small detachments of the macula with rapid deterioration of central vision.

Both "dry" and "wet" macular degeneration can usually be detected by a careful eye examination, but an additional test, called a fluorescein angiogram, is helpful in diagnosing the "wet" form of the disease. In this test, a small amount of dye (called fluorescein because it glows, or fluoresces) is injected into a vein in the arm.The dye then circulates through the body into the eye, and photographs are taken of the macula. These pictures are then studied for any evidence of new blood vessel growth. Based on the results of the fluorescein angiogram, some patients with "wet" macular degeneration can be treated with a laser, which is used to close the leaking blood vessels underneath the macula. In many patients, laser treatment can prevent further visual loss. Both the fluorescein angiogram and laser treatment are safe procedures that can be done quickly in an ophthalmologist’s office.

Any patient over the age of 50 with declining central vision, particularly if distortion or blank spots are noticed, should have a complete eye examination to look for evidence of macular degeneration. Most patients with this disease will have only "dry" changes and will never need a fluorescein angiogram or laser treatment. Many patients with macular degeneration can benefit from low vision rehabilitation services, such as magnifying lenses and large-print reading materials. In addition, there is active research at centers all over the world to search for new ways of diagnosing and treating macular degeneration.

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