The Medical Minute: Macular degeneration causes vision loss in elderly

By David Quillen
Penn State Ophthalmology
Penn State Milton S. Hershey Medical Center
Penn State College of Medicine

By the year 2030, approximately 70 million Americans will be 65 years of age or older. As people age, many will develop health problems. Loss of vision among older Americans is a significant one -- approximately one in three seniors has some form of vision-reducing eye disease. Vision impairment reduces one's ability to perform routine activities such as driving and reading, and increases the risk of depression.

Age-related macular degeneration (AMD) is the leading cause of vision loss in people 65 years of age and older. It is characterized by degeneration of the macula, the area of the back of the eye responsible for the central part of vision and the ability to see details.

AMD can be divided into two categories: nonexudative (or "dry") AMD and exudative (or "wet") AMD. "Wet" AMD is so called because abnormal blood vessels grow in the area and leak fluid, in contrast to the "dry" form in which the affected area deteriorates without leakage. In either form, the nerve cells of the macula are impaired, causing blurred or distorted vision.

Most people with AMD have the nonexudative or "dry" form of the disease. In this type, the eye doctor typically will see pigment changes and localized deposits called "drusen" in the macula. While drusen are the hallmark finding in eyes with AMD, researchers do not completely understand why the drusen develop. Most individuals with "dry" AMD do well with excellent vision, however, they can experience a gradual decline in vision or progress to the more advanced exudative or "wet" form of the disease.

Development of exudative AMD is the most common cause of severe vision loss. While exudative AMD accounts for less than 20 percent of cases of AMD, it is responsible for nearly 90 percent of the cases of vision-loss. Ultimately, a scar forms in the macula, causing permanent vision-loss. In most individuals, vision stabilizes at the 20/400 range -- that is, they can see clearly only the big "E" on the top of the eye chart -- and it does not affect peripheral or side vision. As a result, although people with advanced AMD have difficulty seeing details, they are able to use their side vision to function at a very high level.

An annual eye examination is recommended to detect the signs of AMD in people 65 years of age or older. Seniors with a sudden onset of blurred or distorted vision should be seen quickly to promote early detection and treatment. For some people with nonexudative or "dry" AMD, antioxidant supplementation (vitamins A, C, E and zinc) may reduce the progression of the disease. There is no question that people with AMD should quit smoking and control their blood pressure. Better yet, young and old alike should eat a healthy diet with lots of vegetables and fruit, control blood pressure and stop smoking as soon as possible to reduce their risk.

For those that develop the exudative or "wet" form of the disease, there are treatment options available. Laser treatment, photodynamic therapy, and a new class of medications designed to inhibit abnormal blood vessel growth and leakage may be effective for some patients. Vision rehabilitation with magnifiers and reading devices can help maintain an active life.

We are living longer now. With a little care, the golden years can include healthy eyes and clear vision.