The retina functions like film in a camera, explained ophthalmologist Eric Postel, M.D., of the Duke University Eye Center. Without proper retinal function, images cannot be captured and sent to the brain. The macula is critical for fine, detailed vision. In patients with severe AMD, progressive blurring and loss of central vision due to damage of the macula may leave people unable to perform everyday activities such as driving, reading, writing checks and recognizing faces, he said.
"Fifteen million people in the United States have AMD and 1.5 million have the most severe form," said Postel, the head clinician on the study. "By the year 2030, as the baby boomer generation ages, the number of people with AMD is expected to double."
AMD exists in two forms: the "dry" form and more severe "wet" form. In the dry form, degeneration of the macula can cause slow, progressive vision loss over the course of months to years. While there is no cure, vitamin supplements have been shown to slow the disease in some individuals with this milder form.
In ten percent of patients, the disease progresses to the wet form in which abnormal blood vessels under the macula leak blood and fluid causing rapid damage and a precipitous loss of vision. Patients with wet AMD can receive several treatments to prevent further vision loss -- including laser surgery and recently approved injections of a drug into the eye.
However, available therapies usually can only stall the disease progression, Postel said. None effectively reverse the course of the disease.
While the underlying causes of AMD had remained largely unknown, risk factors include age, smoking, high blood pressure, obesity and diet, said Pericak-Vance. In addition to such environmental factors, evidence from family and twin studies had indicated a significant genetic contribution to the disea
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Contact: Kendall Morgan
kendall.morgan@duke.edu
919-660-1306
Duke University Medical Center
10-Mar-2005