Berkshire Senior Online

By Fred Orlando, M.D.

Macular degeneration is damage or breakdown of the macula of the eye. The macula is the small central point of the light sensing in the back of the eye. It processes the sharp, central vision we use for reading and other fine tasks. When the macula loses its ability to function fully we experience blurriness, darkness or other visual distortions in the center of our vision. This makes close work such as reading or threading a needle difficult or impossible for the unaided eye. Although macular degeneration reduces vision in the center part of the retina it does not affect the eyes’ peripheral vision - the ability of the eye to see objects to the side of center. This means that macular degeneration alone does not result in total blindness.

Sometimes only one eye loses central vision while the other eye continues to see well for many years. The condition may be hardly noticeable in its early stages, but when both eyes are affected reading and close work can become difficult. You may experience one or more of the following symptoms. Colors look dim, words on a page can be difficult to read and can appear broken up. Straight lines can look crooked. There can be a dull or grey area in the center part of vision.

What causes macular degeneration?

Many people develop macular degeneration as part of the body’s natural aging process. Less commonly, macular degeneration can be an inherited condition. Injury, infection, inflammation or extreme nearsightedness may also damage the delicate tissue of the macula. The two most common types of age related macular degeneration are dry (atrophic) and wet (exudative). Dry macular degeneration is by far the most common type. Dry macular degeneration is caused by aging and thinning of the tissues of the macula. Visual loss can range from extremely mild to quite significant and is usually gradual. Wet macular degeneration accounts for about 10% of all cases. Wet macular degeneration results when abnormal blood vessels form at the back of the eye. These new blood vessels leak fluid and/or blood. Leaking fluid distorts and blurs central vision often resulting in dense scar tissue in the macula. Visual loss may be rapid and severe.

Early detection of eye problems can lead to more effective treatment. Periodic eye examinations by an ophthalmologist should be a regular part of general health care to detect problems before they become serious. This is especially critical if you are over 50 or if your family has a history of retinal problems. Many people do not realize that they have a macular problem until blurred vision becomes obvious, yet ophthalmologists can detect earliest stages of macular degeneration through several diagnostic procedures.

Observation of the macula with an ophthalmoscope

A simple test in which the patient looks at a grid resembling graph paper to indicate the loss or distortion of central vision.

A color vision test.

Sometimes an image called a fluorescein angiogram is used to detect abnormal blood vessels within the macula.

Treatment of macular degeneration focuses on helping a person find ways to cope with the visual impairment. Currently there is no cure. Some doctors believe that nutritional supplements may slow the degeneration although scientific evidence is very preliminary. Various low vision optical devices - magnifying devices, closed circuit television, large print reading materials and special lighting - can help to minimize the effects of visual impairment.

People with the less common "wet" macular degeneration can also be helped by low vision optical devices. In its early stages, wet macular degeneration can be treated with laser surgery, a brief and usually painless outpatient procedure. In the last few years a laser procedure has become available called photodynamic therapy or PDT, which allows treatment in some cases that were previously untreatable. Although these procedures cannot cure macular degeneration, they can slow the rate of vision loss.

The greatest risk factor for macular degeneration is advancing age. Risk factors besides advancing age are a family history, a significant amount of exposure to sunlight, and smoking. It is also important to have regularly schedule eye examinations to detect macular degeneration in its earlier stages - a minimum of every two years or sooner if there is a positive family history or if macular degeneration has already been diagnosed. It is also important that any noticeable changes of vision be addressed quickly with a thorough eye examination.

There have been may studies regarding the benefit of nutrition and nutritional supplements in the prevention of macular degeneration, including anti-oxident vitamins and some minerals. There are several commercially available products specifically tailored for eye health. Other nutritional supplements include bilberry. Studies so far are suggestive but certainly not conclusive. Some studies have suggested a benefit from a healthy diet high in fruit and vegetables and low in fat. There is some concern about ingesting an excessive amount of certain vitamins and supplements, however, taken in moderation there may be some protective benefit that future medical studies may support.

More than 10 million Americans are visually disabled by macular degeneration. One area currently being investigated is in the field of genetics. Scientists need to know how genes contribute to the onset of macular degeneration and what genes are most important. An intriguing possibility is that some genes may prevent macular degeneration. Another area of possible treatment is aimed at studying the growth of new blood vessels. Researchers in recent years have discovered a host of natural chemicals in the body that either stimulate or inhibit blood vessel growth. This could affect prevention and treatment of wet macular degeneration. Scientists are also looking into transplanting certain retinal cells that may provide another defense against macular degeneration or even a way to restore lost vision. Other therapies needing initial or further exploration include radiation therapies to destroy abnormal blood vessels; a new surgical technique to remove the leaking vessels; and a trial to see if an extremely low calorie diet can stem the progress of macular degeneration. A highly experimental surgery for one form of macular degeneration has managed to restore sight to a handful of those patients treated. The procedure, known as macular translocation, involves moving the macula away from the underlying diseased area permitting the eye to transmit light images to the brain.