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Here's Spinach in Your Eye

Scientists hope to restore sight using a protein from the leafy vegetable

THURSDAY, Oct. 11, 2001 (HealthDayNews) -- An unlikely source may help restore some vision to millions of people who have macular degeneration and retinitis pigmentosa. What's this miracle substance? It's spinach. But you don't eat it; you stick it in your eye.

Well, actually a surgeon would have to do that, but only if all the lab tests and then tests on animals go well.

Researchers at the U.S. Department of Energy's Oak Ridge National Laboratory and the University of Southern California have discovered a protein in spinach that seems to act like a light receptor in the human eye.

Called a photosynthetic reaction center protein, it helps the plant carry out photosynthesis by changing light energy into electrical energy, says researcher Eli Greenbaum of the Chemical Technology Division of the Oak Ridge National Laboratory. And changing light energy into electrical energy is exactly what goes on in the back of the human eye.

"We discovered a way to extract those molecules from spinach leaves," says Greenbaum. The protein also is present in other plants, not just spinach.

The discovery may be important to millions of people who can't see because the light receptors in their eyes no longer work properly. In a normal eye, light hits the photosensitive cells in the retina, changing that light energy into an electrical impulse that is sent to the brain for interpretation.

Greenbaum and his colleagues hope that one day surgeons will be able to implant the protein in human retinas, replacing damaged cells. There, the new cells would change the energy from light into electrical impulses and restore sight for people with macular degeneration or retinitis pigmentosa.

The Macular Degeneration Foundation says up to 12 million people have the disease in which the center of the retina deteriorates. About 400,000 have retinitis pigmentosa, an inherited disease that affects the light-sensitive cells that allow you to see in dim light, reports Prevent Blindness America.

The researchers suspect the spinach protein could help these people because the nerve fibers that carry electrical signals to their brains usually are still intact. Only the light receptors are damaged. The protein doesn't have the potential to help people with other eye disorders, like glaucoma, in which the optic nerve, not light receptors, is damaged

Greenbaum say the work is in only the very early stages and is limited to Petri dishes in the lab. He says any animal testing is at least two to three years away.

Dr. Robert Josephberg, an assistant professor of ophthalmology at New York Medical College in Valhalla, N.Y., says even if it works, the procedure probably would allow people to see only large images, like the big E on an eye chart or a hand moving in front of them. It would probably not restore enough sight for reading.

"Basically this is Star-Wars technology," he says. "This is in the very experimental stages, but it raises the hope that someday we might be able to help legally blind people see large images."

What To Do

In case you've forgotten basic plant biology, here's a primer on photosynthesis.

For more information on macular degeneration, go to the Macular Degeneration Foundation. To read about retinitis pigmentosa, check Prevent Blindness America.

SOURCES: Interviews with Eli Greenbaum, Ph.D., professor of genome science and technology, University of Tennessee, Knoxville, and corporate fellow, Clinical Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tenn.; Robert Josephberg, M.D., assistant professor of ophthalmology, New York Medical College, Valhalla, N.Y.
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