Treatment Options for Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is a progressive disease of the eye occurring in people over 55 years old due to the aging process. The macula is the central part of the retina which lines the inner wall of the eye and provides central vision. In AMD, damage to the macula results in loss of central vision and affects a person's ability to read, recognize faces or drive. The peripheral vision is usually spared.

Up to 30 million people worldwide have AMD. Up to 200,000 people in the US are diagnosed with AMD each year. It is the leading cause of blindness in older populations in the US. As we live longer and longer, we will see an increase in AMD. AMD is associated with aging, fair skin, light iris color, hypertension, smoking, arteriosclerosis, prolonged exposure to sunlight, and family history of AMD.

There are 2 types of AMD: the "dry" form and the "wet" form, based on the absence or the presence of abnormal growth of blood vessels under the retina. Most people with AMD have the dry form. Currently there is no proven treatment for the dry type, but the loss of vision tends to be milder and the disease progression is rather slow.

Approximately 15% of patients with AMD have the wet form, where there is a growth of abnormal blood vessels under the retina, which can cause leakage, bleeding, and scarring, resulting in more rapid and severe vision loss. About 80% of severe vision loss is due to the wet form as compared to 20% due to the dry form.

The wet form can manifest in two types: classic or occult. Over 70% of patients with the wet form have the occult type. So far, only the classic wet type is treated with conventional laser photocoagulation to stabilize vision or to limit the growth of abnormal blood vessels. The remaining majority of patients with wet AMD can not be treated with the laser procedure. Also, the current laser treatment does not improve vision in most treated eyes because the laser destroys not only the abnormal blood vessel but also the overlying macula. Better treatment options are obviously needed.

A surgery called "limited retinal translocation" is an option for patients with wet classic AMD where the abnormal blood vessel is located just below the macula and laser treatment will most certainly damage the macula resulting in permanent loss of central vision. In this procedure, the eye wall is shortened and the macula is moved away from the abnormal blood vessel under it. Then laser surgery can be performed to destroy the abnormal blood vessels without harming the macula. Initial results show that significant improvement in vision is possible with this procedure. However, this benefit has to be weighed against the risk of undergoing surgery, possible loss of vision, and the unpredictable nature of the surgical outcome.

Another exciting treatment option is for the occult type of wet AMD, which could not be treated previously. We at the Froedtert & Medical College Eye Institute are currently enrolling patients to determine the efficacy of a special type of laser that may destroy the abnormal blood vessels without damaging the macula. Eligibility can be determined only by a test called the fluorescein angiogram and an eye examination. Also treatment is offered only for patients with recent onset of problems with wet AMD, who have not already developed scarring of the macula.

Finally, a laser treatment called photodynamic therapy is an option for some patients with wet AMD. It uses a photosensitizing dye that is injected intravenously and is stimulated to close off the abnormal blood vessels under the macula. It has been approved for clinical use in Switzerland and is awaiting FDA approval in the U.S.

We still need to do much more research into the cause and progression of AMD, as well as develop better treatments. As the aging population grows, the need will become more desperate. At the Froedtert & Medical College Eye Institute, we are dedicated to saving sight and developing better care for patients with eye diseases, such as AMD. We will continue to strive to provide leading-edge treatments for patients who otherwise would lose sight.

MCW Health News presents up-to-date information on patient care and medical research by the physicians of the Medical College of Wisconsin.