UNIVERSITY OF UTAH RESEARCHERS DEVELOP NEW TEST TO AID IN EARLY DETECTION AND PREVENTION OF EYE DISEASE

University of Utah, John A. Moran Eye Center
March 14, 2001
--------------------------------------------------------------------------------

A new device developed by University of Utah ophthalmology and physics researchers could eventually help physicians slow, and possibly prevent, the onset of age-related macular degeneration in some patients. Macular degeneration is the leading cause of blindness in the people over age 65; it affects more than 13 million Americans.

The new device uses a low-energy laser method, known as resonance Raman spectroscopy, to measure the levels of two macular carotenoid pigments called lutein and zeaxanthin, according to Paul S. Bernstein, M.D., Ph.D., assistant professor of ophthalmology and visual sciences at the University of Utah’s Moran Eye Center. The pigments, which are found in dark green leafy vegetables (such as spinach, broccoli, collard greens and kale) and yellow and orange colored fruits and vegetables (such as peaches, nectarines, persimmons and corn), are widely thought to protect the eye from light-induced oxidative damage and aging.

“Both lutein and zeaxanthin are potent antioxidants. They effectively absorb the blue region of the visible spectrum—the most damaging wavelengths of light to which the retina is routinely exposed,” said Bernstein. “This new test will allow us to determine whether raising a patient’s macular pigment levels through diet and nutritional supplements translates into a lower risk for macular degeneration.”

Bernstein says that the non-invasive test, which takes less than one second, could become as common as tests for high cholesterol and blood glucose levels. “If, based on the results of this test, a physician determines a patient has low levels of macular pigment, that patient could be encouraged to increase consumption of foods or nutritional supplements containing lutein and zeaxanthin. It is possible that we could slow, or even prevent, onset of macular degeneration,” he said.

The new test is unique because it uses Raman spectroscopy, a technology traditionally considered unsuitable for routine measurements in living tissue, according to Werner Gellermann, Ph.D., research professor in the University of Utah’s Department of Physics and associate director of the university’s Dixon Laser Institute where the technique was developed. “Raman signals are typically of weak intensity and therefore we usually need to use lasers in combination with sophisticated light collection and analysis instrumentation,” he said.

What Gellermann and Bernstein found, however, was that macular pigments in the eye exhibit extremely strong Raman signals when excited with blue laser, a phenomenon termed resonance enhancement. “Lutein and zeaxanthin seemed uniquely suited for Raman spectrometry. The pigments literally glow green when a blue laser light shines on them. Under proper conditions, this resonance amplification can be as high as a factor of 10,000, turning a weak signal into a readily measured strong signal many times higher than background signals from other cells in the retina. This allows us to expose the retina to light exposure levels that are well within established safety ranges,” he said. “As physicists, we’re trained to not to stare into lasers. But, when our colleagues at the Moran Eye Center pointed out the strong need to measure macular pigments in a non-invasive and objective way, we decided to take this unique laser approach,” said Gellermann. “This has very much been a team effort.”

Bernstein says the new technique also can be used with higher reliability in patients with significant visual loss from macular degeneration or other diseases—unlike heterochromatic flicker photometry (the most commonly used test to measure macular pigments).

The University of Utah researchers recently received a United States patent on the device and Bernstein is currently recruiting adults of all ages to participate in clinical trials to determine its effectiveness. The team’s latest findings were published in the February 15, 2001 issue of the physics journal Optics Letters.

Bernstein and Gellerman’s research was initially funded by the State of Utah Centers of Excellence Program. Recently, the researchers obtained a $500,000 STTR grant from the National Institutes of Health (NIH) and the National Eye Institute (NEI). They have also formed a start-up company, Spectrotek to develop the device for routine testing in eye clinics. Based on the results of their current clinical study, the researchers predict that the device could reach the market by 2003.

For more information about enrolling in the clinical study of the new device, contact the Moran Eye Center’s clinical studies office, 801-581-6265.

[Read Original Article]