Cleveland Clinic Researchers Focus in on Causes of Age-Related Macular Degeneration

CLEVELAND -- Researchers at The Cleveland Clinic Cole Eye Institute have begun to unlock the secrets of drusen, material that collects in the eye and increases a person's risk of developing age-related macular degeneration.

As many as 10 million Americans already have lost their sight to age-related macular degeneration (AMD), with hundreds of thousands of new cases being diagnosed each year. The disease causes a portion of the retina to break down, resulting in the loss of high-definition, central vision. Currently, there is no known cause or cure.

But Cleveland Clinic research to be published in the Nov. 12 edition of Proceedings of the National Academy of Sciences is revealing the mechanism of this devastating disease. Led by John W. Crabb, PhD and Joe G. Hollyfield, PhD, Cole Eye Institute researchers collected samples of drusen from 18 healthy donor eyes and five AMD-afflicted donor eyes using a new isolation technique developed by Hollyfield. All of the eyes were from donors age 56 or older.

Researchers then analyzed the drusen using new, more sensitive techniques that combine liquid chromatography and mass spectrometry methods. This analysis identified 129 proteins. Up to 65 percent of the proteins found in drusen were present in both normal and AMD-afflicted eyes.

But Crabb and Hollyfield also found important differences. In the AMD-afflicted eyes, more of the drusen proteins had been modified by oxidative damage. Future research will focus on how these protein modifications affect drusen formation and the onset of AMD.

"Our research is the first to establish a molecular connection between oxidative damage and age-related macular degeneration," Crabb said. "Our goal is to take this knowledge, expand upon it, and find a way to halt or slow drusen formation and AMD itself."

Existing studies already have found that smoking (which promotes harmful oxidation) increases a person's risk of developing AMD and that high daily doses of anti-oxidant vitamins and zinc slow the disease's progress.

"Our results open up avenues for therapeutic research, which might block biological pathways that contribute to the oxidative damage," Hollyfield said.

Crabb and Hollyfield recently were awarded two federal research grants from the National Eye Institute totaling $3.7 million to extend their AMD research activities.

"Eye donations are critical to the continued success of this program," said Hollyfield, who also oversees the Foundation Fighting Blindness' national donor eye collection center, now housed at the Cole Eye Institute. "Without people making this selfless gesture, targeted eye disease research like this could not proceed and AMD would continue to remain a mystery and rob precious eyesight."

More information about becoming an eye donor is available by calling the Foundation Fighting Blindness at 800/683-5555 or by visiting its website at www.blindness.org .

The Cleveland Clinic Cole Eye Institute, under the leadership of Hilel Lewis, MD, is ranked one of the top eye care departments in the country, according to a recent survey published by U.S. News & World Report. More than 125,000 patients were treated at the Institute in 2001. The Institute has state-of-the-art eye clinics, operating rooms for eye surgery, and extensive laboratory and clinical space dedicated to research on age-related macular degeneration and inherited retinal disease.

The Cleveland Clinic Foundation, founded in 1921, integrates clinical and hospital care with research and education in a private, not-for-profit group practice. Approximately 1,100 full-time salaried physicians at The Cleveland Clinic and Cleveland Clinic Florida represent more than 100 medical specialties and subspecialties. In 2001, there were more than 2.25 million outpatient visits to The Cleveland Clinic Foundation. Patients came for treatment from every state and from more than 80 countries. There were nearly 52,000 hospital admissions to The Cleveland Clinic in 2001.

Source: PRNewswire