Radiation therapy offers hope to patients with common cause of blindness, suggest researchers
Tens of thousands of people who suffer from the leading cause of legal blindness may benefit from radiation therapy to stabilize the deterioration of their vision, according to New York researchers presenting their work here today (Dec. 2) at the 84th Scientific Assembly and Annual Meeting of the Radiological Society of North America (RSNA).
Age-related macular degeneration (AMD) of the "wet" type is a debilitating condition that affects 170,000 Americans, most age 60 and older, and women more often than men, according to the National Eye Institute, a division of the National Institutes of Health. The condition is becoming increasingly common as the population ages.
Wet AMD occurs when tiny blood vessels break through a membrane behind the retina and leak blood and fluid, causing increasing loss of central vision, while leaving peripheral vision intact.
Radiation therapy appears feasible for all people with wet AMD, while only 15 percent of people with the condition are eligible for laser surgery, the current standard treatment. Neither laser surgery nor radiation therapy can prevent progression of the disease, but radiation therapy appears to prevent or delay further vision loss in the majority of people with wet AMD.
According to one of the largest studies with long-term follow-up, 90 percent of 146 people treated with radiation therapy at the State University of New York Health Science Center at Syracuse, experienced stabilized vision after six months. After one year, 60 percent of 84 patients experienced stabilized vision. The age of the patient was not a factor in the outcome.
"If this treatment delays progression of the condition by even two years, it's worth it," said Robert H. Sagerman, M.D., professor of radiation oncology at State University of New York Health Science Center at Syracuse, who reported the study's findings. "We're finding the earlier people are treated, the more successful it is."
The treatment involves exposing the macula in the center of the retina to low-dose radiation treatments once a day for up to two weeks.
Researchers have not detected any side effects. Although radiation therapy for AMD is a relatively new treatment, it is widely available because a similar therapy is being used regularly by radiologists in hospitals around the world.
"Radiation oncologists have extensive experience treating people with eye cancers using four or five times the amount of radiation used in this treatment," said Dr. Sagerman. "It's early, but the results of radiation therapy are promising for macular degeneration."
Because this type of AMD can progress quickly, it is important that anyone experiencing problems see an ophthalmologist. Early signs of AMD include decreasing or blurred central vision and straight lines that appear wavy. Although AMD typically affects people age 60 and over, it can strike as young as age 50.
Risk factors for AMD include: gender--more women are affected than men-- smoking, family history of the disease and high cholesterol.
Although AMD of the dry type is more common than the wet type, affecting more than 1.5 million people, it progresses very slowly and rarely causes legal blindness. There is no known treatment for dry AMD.
Co-authors of a paper on the topic being presented by Dr. Sagerman are: Sri G. Gorty, M.D.; William V. Delaney, Jr., M.D.; G.R. Hampton, M.D.; Samuel C. Spaulding III, M.D.; and Bryan K. Rutledge, M.D.
The RSNA is an association of 30,000 radiologists and physicists in medicine dedicated to education and research in the science of radiology. The Society's headquarters are located at 820 Jorie Blvd., Oak Brook, Illinois 60523-2251.