Macular Degeneration
Age–related macular degeneration (AMD) is a disease caused by the breakdown of the macula, the small part of the eye's retina that is responsible for central vision. This condition affects both distance and close vision and can make some activities, such as threading a needle or reading, very difficult or impossible. Macular degeneration is the leading cause of severe vision loss in people over 65 years old. (below: Simulated loss of central vision)
Macular Degeneration Symptoms
The visual symptoms involve distortion or a large blind spot in the center of the visual field. Side vision is not affected; rather, the sharp, straight–ahead vision necessary for driving, reading, recognizing faces, and looking at detail is lost. Straight lines may appear crooked.
While age is the most significant risk factor for developing AMD, heredity, blue eyes, high blood pressure, cardiovascular disease, and smoking have also been identified as risk factors.
Types of Macular Degeneration
Ninety percent of the people who have AMD have the dry type of AMD. This form of AMD is characterized by a buildup of material under the macula. It often takes many years to develop, and vision loss tends to occur gradually.
The wet type of AMD is more serious and occurs in 10% of those diagnosed with this disease. Vision loss may be gradual or sudden. In this form of AMD, abnormal blood vessels grow in a layer beneath the macula, leaking fluid and blood, damaging the retina and creating distortion or a loss of central vision. A dye test is performed to help diagnose which form of AMD is present.
Treatment
For the wet type of AMD, treatment is focused on preserving what central vision remains. Laser treatment or a new procedure, known as photodynamic therapy (PDT), can help prevent further loss of vision. The benefit of PDT is that it may inhibit abnormal blood vessel leakage associated with wet AMD, and may limit further damage to the overlying retina.
Unfortunately, the abnormal blood vessels may re–grow or begin to leak again. Every three months, a repeat examination, including a dye test, is required. Multiple treatments may be necessary.
For the dry type of AMD, there is no treatment; however, it is important to be examined regularly, as wet type AMD may also develop.
Macular Degeneration and Nutritional Supplements
Although the exact causes of AMD are not fully understood, a recent scientific study shows that antioxidant vitamins and zinc may reduce the impact of AMD for some people with the disease.
It is very important to remember that vitamin supplements are not a cure for AMD, nor will they restore vision already lost from the disease.