Age-related macular degeneration (AMD) is a disease associated with aging that gradually destroys sharp, central vision. Central vision is needed for seeing objects clearly and for common daily tasks such as reading and driving. AMD affects the macula, the part of the eye that allows you to see fine detail. In some cases, AMD advances so slowly that people notice little change in their vision. In others, the disease progresses faster and may lead to a loss of vision in both eyes. Macular degeneration is a leading cause of vision loss in Americans 60 years of age and older.
The greatest risk factor for macular degeneration is age. However, other risk factors include smoking, obesity, family history, gender (women are more at risk than men), and race (Caucasians are more likely to develop the condition than African Americans).
There are two types of macular degeneration: wet and dry.
Wet macular degeneration occurs when abnormal blood vessels behind the retina start to grow under the macula. These new blood vessels tend to be very fragile and often leak blood and fluid. The blood and fluid raise the macula from its normal place at the back of the eye, causing rapid damage to the macula. With wet AMD, loss of central vision can occur quickly.
An early symptom of wet AMD is that straight lines appear wavy. If you notice this condition or other changes to your vision, contact your eye care professional at once. You will need a comprehensive dilated eye exam.
Dry macular degeneration occurs when the light-sensitive cells in the macula slowly break down, gradually blurring central vision in the affected eye. As dry AMD gets worse, you may see a blurred spot in the center of your vision. Over time, as less of the macula functions, central vision is gradually lost in the affected eye.
The most common symptom of dry AMD is slightly blurred vision. You may have difficulty recognizing faces. You may need more light for reading and other tasks. Dry AMD generally affects both eyes, but vision can be lost in one eye while the other eye seems unaffected. One of the most common early signs of dry AMD is drusen.
Drusen are yellow deposits under the retina. They often are found in people over age 60. Your eye care professional can detect drusen during a comprehensive dilated eye exam. The dry form can advance and cause vision loss without turning into the wet form. The dry form also can suddenly turn into the wet form, even during early stage AMD. There is no way to tell if or when the dry form will turn into the wet form.
Wet AMD can be treated with laser eye surgery, photodynamic therapy, and injections into the eye. These injections are medications that inhibit vascular endothelial growth factor. None of these treatments is a cure for wet AMD. The disease and loss of vision may progress despite treatment.
Once dry AMD reaches the advanced stage, no form of treatment can prevent vision loss. However, treatment can delay and possibly prevent intermediate AMD from progressing to the advanced stage, in which vision loss occurs.
The National Eye Institute's Age-Related Eye Disease Study (AREDS) found that taking a specific high-dose formulation of antioxidants and zinc significantly reduces the risk of advanced AMD and its associated vision loss. Slowing AMD's progression from the intermediate stage to the advanced stage will save the vision of many people.