Ask the Doctor at Saint John’s: Shedding Light on Macular Degeneration

Q: What part of the eye is affected by macular degeneration?

By Thomas Hanscom, M.D., retinal surgeon, Saint John’s Health Center

Macular degeneration affects the retina, a layer of tissue on the inner backside of your eyeball. The macula is the center of the retina, and as you age, the macula can deteriorate. When degeneration occurs, central vision is affected; peripheral vision remains unencumbered. Because people depend on adequate central vision for so many activities, macular degeneration can have a huge impact on one’s lifestyle.

Dry macular degeneration occurs when retinal pigment epithelial (RPE) cells become damaged from atrophy (the RPE is a layer of tissue forming the outermost surface of the retina). Vision can become blurred, greater illumination may be needed for reading, and colors may appear less bright. Blurred or blind spots can appear in the center of vision.

Wet macular degeneration develops when new, abnormal blood vessels develop underneath the macula. These blood vessels are fragile and can begin to leak fluid or blood. Symptoms may include visual distortion, a central blurry spot, or decrease in central vision. This type only accounts for about 15 percent of all macular degeneration, but it is more severe. Legal blindness can result.

In both forms of macular degeneration, onset can begin in one eye while the other eye compensates for changes, so people may not be aware it’s happening for some time. A simple test you can perform is to place your hand over one eye, then the other. If any of the symptoms discussed are occurring in either eye, see a doctor immediately.

At the moment there's no treatment to reverse dry macular degeneration. It usually progresses slowly, however, and many with this condition live productive lives.

Recently, great strides have been made in drug treatment of wet macular degeneration. Here’s the latest:

Macugen, approved by the FDA in 2004, stops formation of new abnormal blood vessels and decreases leakage from existing ones. It’s injected directly into the white part of the eye.

Lucentis also inhibits new growth of abnormal blood vessels. Furthermore, it shows promise in reversing the effects of macular degeneration. It’s currently available only in clinical trials.

Avastin was originally developed for treatment of colon and rectal cancer. It works similarly to Lucentis, and shows great promise for treating wet macular degeneration. Avastin is currently the treatment preferred by the majority of retinal specialists in the United States.

Factors essential to maintaining a healthy heart, such as not smoking, good nutrition, and control of body weight and blood pressure, have some role to play in prevention of macular degeneration.

Unfortunately, the causes of macular degeneration are approximately 90 percent genetic. But many coping aids exist. And with exciting advances in treatment for wet macular degeneration, in addition to ongoing research into prevention and treatment of dry macular degeneration, important new therapies are sure to emerge.

Thomas Hanscom, M.D., is a retinal surgeon on staff at Saint John’s Health Center. For more information about Dr. Hanscom or other Saint John’s services, please call (310) 829-8990 or visit the website at www.stjohns.org.

For a physician referral or a second opinion, please call 1-888-ASK-SJHC.
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