Macular Degeneration

By Kenneth N. Darvin, M.D.

Macular degeneration is the leading cause of blindness in people over the age of 50 in the United States. The macula is a small area of the retina located at the back of the eye that allows us to see fine details clearly. Macular degeneration is defined as the damage or breakdown of this part of the retina, where images are focused. The very center of this area of the retina is called the fovea. A disturbance in the macula can result in a distortion or deterioration of fine detailed vision. People may experience blurriness or darkness in the center of their vision. Macular degeneration is the term used to describe what is occurring: the macula is degenerating. Macular degeneration can be due to many reasons.

As people get older, changes are found in the macula. This is called age related macular degeneration. What the ophthalmologist sees on examination with an ophthalmoscope can range from little yellow deposits called "drusen," to areas of increased or decreased pigmentation of the retina. These pigmented areas are made up of cells that give the retina its nutrients and take away its waste. The build-up of these breakdown products or changes in pigmentation of the retina can be noticed by the patient as a distortion or deterioration in their distance or near vision.

Macular degeneration does not affect the peripheral vision. This is very important, as a common fear of patients is "Am I going to go blind?" It must be explained to patients that they may lose their central vision, but they will retain their peripheral vision. This vision allows them to be mobile and very functional. Once a patient is given the diagnosis of macular degeneration they are asked to monitor the condition themselves. They are given an "Amsler Grid" and asked to monitor the grid for any changes or distortion. If any changes are noted they are instructed to notify their ophthalmologist immediately.

The incidence and progression of macular degeneration increases with age. Ten percent of people 66-74 years of age will have some findings of macular degeneration. This increases to approximately 30% in people 75-85 years of age. Sometimes only one eye loses vision while the other eye continues to see well for many years.

Macular degeneration is best described as being one of two types. Macular degeneration may be referred to as the "wet" (exudative) or "dry" (atrophic) type. In the "dry" type we see the changes in the pigmentation as yellow deposits within the retina. Vision loss is usually gradual. In the "wet" type we see elevation of the retina. This is due to fluid leaking from new blood vessels that are bleeding. The changes that these patients may experience in vision can be very sudden and dramatic. Most patients, 90%, have the "dry" form of macular degeneration. Ten percent have the "wet" type. This group makes up the majority of patients with visual loss, approximately 75-90%.

Patients may have macular degeneration and still have 20/20 vision. When they begin to have clinical manifestations of macular degeneration they may describe the words on a page as looking blurry, a dark or empty area may appear in their center of vision, and/or straight lines may look distorted or wavy.

When the patients notice changes in their vision and the ophthalmologist notices changes suggestive of "wet" macular degeneration, a fluorescein angiogram is ordered. During this exam a dye is injected into a vein in the arm. This dye passes through the blood vessels in the back of the eye and pictures of the eye are then taken. The ophthalmologist looks for areas where the dye is leaking. Based on the type of leakage seen, laser treatment itself does not help restore vision but can help to prevent further deterioration. In approximately 50% of the cases lasered, the blood vessels can recur and the laser treatment itself may cause a noticeable black spot in the patient's vision.

Fortunately, there are many studies for other treatments of macular degeneration underway. One of the most promising treatments utilizes a chemical that is absorbed by the abnormal blood vessels. The chemical is then activated by a laser and only destroys the abnormal blood vessels, not the retina. Although this treatment is not a cure and requires retreatment every few months, it does not damage the retina. The chemical is in final studies for FDA approval and, hopefully, will be available early next year.

Some of the risk factors associated with macular degeneration are hereditary. Currently more and more studies are pointing to this. Other factors that may influence macular degeneration are smoking, hypertension, farsightedness and diet. Patients often ask what they can do to prevent macular degeneration or its progression. Many of their questions pertain to dietary supplements, vitamins, and minerals. There is theoretical scientific basis for these to work, but no studies have shown conclusively that they are beneficial. In fact, a recent study has shown that statistically these supplements are not beneficial.

Dr. Kenneth Darvin is a board-certified ophthalmologist who is fellowship trained in diseases of the retina and vitreous. Dr. Darvin is a graduate of SUNY Medical School in Brooklyn, New York. He is a specialist in management of the diabetic eye. Dr. Darvin has a special interest in inflammatory conditions of the eye, such as Lupus, and the resultant effect of the disease on the eyes. Dr. Darvin performs fluorescein angiography and laser surgery, including the treatment of retinal detachments by pneumatic retinopexy. He practices at the Santamaria Eye Center located in Edison and Perth Amboy. He is on the staff of Robert Wood Johnson Medical Center.