Macular degeneration is deterioration of the macula in the eye. The macula is a tiny structure in the middle of the retina that helps produce central vision. The retina is a tissue that lines the back of the eye and sends visual signals to the brain. Macular degeneration causes a gradual destruction of sharp, central vision. Macular degeneration is primarily a disease of aging, although in rare cases it can occur in younger people.
Adult (or age-related) macular degeneration (AMD) occurs in two forms:
Dry AMD
Ninety percent of all people with AMD have this type. An area of the retina becomes diseased, leading to the slow breakdown of cells in the macula, and a gradual loss of central vision.
Wet AMD
Although only 10% of all people with AMD have this type, it accounts for the majority of all blindness from the disease. As dry AMD worsens, new blood vessels may begin to grow and cause "wet" AMD. These new blood vessels often leak blood and fluid under the macula. This can lead to permanent damage of the macular region.
Causes
The cause of adult macular degeneration is not known.
Risk Factors
A risk factor is something that increases your chance of getting a disease or condition. Risk factors for AMD include:
Symptoms
In some people, macular degeneration advances so slowly that it has little effect on their vision. But in others, the disease progresses faster and may lead to significant vision loss. Both dry and wet AMD cause no pain.
Symptoms include:
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Blurred vision (an early sign)
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Difficulty seeing details in front of you, such as faces or words in a book
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Blurred vision that goes away in brighter light
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A small, but growing blind spot in the middle of the field of vision
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Straight lines appear crooked
Diagnosis
The doctor will ask about your symptoms and medical history, and perform a physical exam. The doctor may suspect AMD if you are over age 60 and have had recent changes in your central vision. To look for signs of the disease, an ophthalmologist or optometrist will use eye drops to dilate (enlarge) your pupils to view the back of the eye.
You may also be asked to view an Amsler grid, which is a pattern that looks like a checkerboard. Changes in your central vision will cause the grid to appear distorted, a sign of AMD.
Treatment
Treatment may include:
Dry AMD
There is currently no treatment for dry AMD. Research has shown that certain vitamins and minerals may slow the progression of the disease in some people.
Wet AMD
Some cases of wet AMD can be treated with laser surgery. This treatment involves aiming a strong light beam onto the new blood vessels to destroy them. Photodynamic therapy is a type of treatment that involves injecting a light-sensitive dye into the bloodstream. Then affected areas in the back of the eye are hit with a special laser to activate the dye and destroy certain blood vessels. Laser surgery is a short procedure performed by ophthalmologists in their offices or in eye clinics.
Another way to treat wet AMD is an injection of a special medication, called a vascular endothelial growth factor (VEGF) inhibitor, into the vitreous in the back of the eye. This treatment usually needs to be repeated indefinitely.
Prevention
There are no guidelines for preventing adult macular degeneration because the cause is unknown. You should have your eyes examined regularly, as suggested by your physician. Don't smoke and consider taking a multivitamin with antioxidants everyday. If you have AMD, your doctor may advise you to monitor for problems by using an Amsler grid at home. Surgery can sometimes prevent wet AMD from completely destroying your central vision
RESOURCES:
American Macular Degeneration Foundation
http://www.macular.org
Macular Degeneration Foundation
http://www.eyesight.org
References:
Macular Degeneration Foundation website. Available at: http://www.eyesight.org.
National Eye Institute website. Available at: http://www.nei.nih.gov/.
