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What you should know about Age Related Macular Degeneration
By Andrew Danyluk, M.D.
Age related macular degeneration, (ARDM), is a disorder that affects the most sensitive part of the retina that is responsible for our finest vision. It is called age related because its incidence increases with older age. While 1% of those younger than 60 have it, the incidence increases to 5% for those over 80.
Symptoms of macular degeneration can range from a mild gradual loss of central vision to a sudden painless blindness with all of the vision obscured. Usually the mild loss occurs in both eyes whereas sudden loss is usually only in one eye. Most often, straight lines will appear wavy or distorted in the middle. Daily monitoring straight lines with one eye covered by looking either at the edge of a door, window blinds or using reading glasses to look at graph paper is a very useful way of detecting any change in the macular degeneration. If any change occurs in the perception of the lines then an ophthalmologist should be notified promptly.
The retina is much like the film in a camera. The retina in the central few millimeters in the back of the eye has a much greater density of specialized cells that detect light known as photoreceptor cells, which give us our sharp central vision. The high density of photoreceptors in the macula requires greater maintenance from the supporting tissue. The supporting tissue is made up of the choroid, which has an extensive blood supply, and maintenance cells called the retinal pigment epithelium. These maintenance cells are intimately connected to the photoreceptor cells and their function is to provide nutrients, recycle waste and form a light barrier that allows the retinal photoreceptors to maximally capture light energy. When these macular retinal pigment cells begin to lose function, macular degeneration begins. At first retinal photoreceptor waste products accumulate, later both macular pigmentary cells and photoreceptors die. This is known as “dry” macular degeneration. Eventually, scar tissue from the choroid invades the retina in an effort to heal the damage, but the scar tissue is unstable and can leak blood and fluid into the retina causing further retinal damage, called “wet” macular degeneration.
What causes macular degeneration has not been determined, but we can only infer that the accumulated effects of years of ultraviolet light exposure and poor circulation cause oxidative damage to the pigment epithelial cells. Given the risk factors of aging, family history, atherosclerosis and cigarette use, it is important for individuals over age 60 with risk factors to have a yearly ophthalmic examination as well as general medical examination. The primary care physician should evaluate and treat cardiovascular risk factors. An ophthalmologist knowledgeable in macular degeneration should see affected individuals as often as their condition dictates.
Treatment for macular degeneration is divided into preventative measures and therapy for the “wet” type. Preventative measures were developed in 2001 when it was determined that patients with moderate macular degeneration who used high dose antioxidant vitamin supplements with zinc had a 25% reduction in their risk of progressing to the worse forms of macular degeneration. In 2003, drugs that blocked the chemicals that caused the scar tissue vessels to develop were injected directly into the eye, stabilizing vision in a majority of patients. In 2006 more potent versions of these drugs were developed that for the first time allowed some patients to recover lost vision.
Because of the tremendous burden of macular degeneration a great deal of research is being devoted to both prevention and treatment, giving hope to the countless numbers of people who have gone blind from macular degeneration.
Dr. Andrew Danyluk is Associate Professor of Ophthalmology and Internal Medicine at the University of Massachusetts. His office is in the Medical Arts Complex at Berkshire Medical Center and he can be reached at 499-6405.