Ophthalmology and physics researchers at the University of Utah have come up with a simple, fast test that may help researchers detect a propensity to developing macular degeneration, the leading cause of blindness in older people. They hope the test will allow physicians to delay or even prevent the disease.
More than 13 million Americans suffer from macular degeneration, which generally affects the center of the field of vision. Despite how common it is, it's not very treatable or even well understood, according to Dr. Paul S. Bernstein, assistant professor of ophthalmology and visual sciences at the U.'s Moran Eye Center.
The issue — and it has been hotly contested in some quarters — is whether nutrition affects the disease. Two macular carotenoid pigments, lutein and zeaxanthin, found in dark green leafy vegetables such as broccoli and spinach and yellow and orange fruits and vegetables such as peaches, persimmons and corn are believed by many to protect the eye from oxidation and aging damage. It's a fact that the two pigments are found in higher concentrations in the eye's macula than anywhere else in the body.
It's also a fact that levels tend to decrease with age, while the incidence of macular degeneration goes up.
The new test, called resonance Raman spectroscopy, examines lutein and zeaxanthin pigment levels in the eye, in hopes of determining whether those levels are indeed significant and, if so, whether increased intake, either in food or a dietary supplement, could prevent or at least delay macular degeneration.
A test already in use, called heterochromatic flicker photometry, measures the pigment levels, but it's complicated and requires "a very attentive person with visual acuity" in order to work. And senior citizens often have trouble with it, according to Werner Gellermann, research professor in physics and associate director of the U.'s Dixon Laser Institute, where the test was developed. The older test is also more limited in who it can be used on.
"Initially, we thought it was a long shot we could use it on a live, human eye," Bernstein said. But it turned out the eye's macular pigments, when stimulated by a blue laser, show strong Raman signals that are easily measured. The whole test takes a half second for each eye.
During the test, an individual looks into a hole and lines up a colored area so it visually overlaps a spotted one. The laser is sent into the tube, to the eye. Then the machine collects the Raman light, draws a spectrum that's sent to the spectrometer and it tells the computer the levels of lutein and zeaxanthin. High readings are considered good. Those with low readings may eventually, If the study proves what the researchers hope, be told to increase their intake of the two pigments.
The test can be conducted with vision correction such as glasses or contacts in place.
Since October, researchers Steven Wintch and Da You Zhao have tested 300 people ages 21-91. That's the first part of a three-phase study: Getting lots of people tested. Later, they'll do the test on folks both before and after cataract surgery. Finally, they will see if supplementing lutein and zeaxanthin in the diet helps. And they want to measure their test's effectiveness against the old method.
The initial research was funded by the State of Utah Centers for Excellence Program and they most recently got a boost from a $500,000 grant from the National Eye Institute and the National Institutes of Health.
Anyone interested in participating in the clinical study may call the center, 1-801-581-6265.