ELECTRONICS MAY HOLD KEY TO RESTORING SIGHT.
Mrs. Brown was nervous.
Eugene de Juan was just about to pull her right eyelid up with clamps, poke a hole through her eye with a mean-looking tool and then send bolts of electricity hurtling into the retina of the 64-year-old North Carolinian.
Lying under a surgical sheet, surrounded by tubes and dials and meters, by blinking machines that beeped in rhythm with her heart and operating lights that shone in her face, she confessed her fears.
De Juan, a surgeon at Johns Hopkins School of Medicine here, looked puzzled. ``What exactly are you nervous about?'' he asked.
To de Juan, the equipment that looks ominous to Brown is part of a scientific quest, the search for artificial sight. Despite her last-minute nerves, Brown, who has almost no central vision, is willingly part of that quest.
Along with dozens of scientists and engineers across the country, Brown and de Juan are probing the mysteries of sight in order to accomplish the amazing. They want to get the blind to see. And they think electronics can show the way.
The purpose of the experiment on Brown, who would not give her first name, was to understand how electrical signals given to the retina translate into the perception of light. Building on this knowledge, scientists eventually hope to implant electrodes at the retina, or even in the brain, to do the work our eyes do.
While this isn't the stuff of miracles, within about a dozen years it could benefit hundreds of thousands of people with severely impaired vision.
``They will have a visual sense that will be vastly inferior to normal vision, but vastly superior to being blind,'' said Richard A. Norman, a scientist at the University of Utah in Salt Lake City.
Some 100,000 Americans are either completely blind or can only distinguish between light and darkness. Some 600,000 to 900,000 people have sight so diminished they are declared legally blind. And 3 million others have low vision, chronic conditions that cannot be corrected with glasses or contact lenses, according to the federal government.
The leading causes of vision deterioration are cataracts, macular degeneration - the deterioration of the crucial middle portion of the retina - and diabetic retinopathy. In diabetic retinopathy, blood hemorrhages in the eye obstruct vision or destroy the retina, the sensitive tissue at the back of the eye that has the crucial cells that respond to light.
All these conditions affect the eyes. Since the central organ of human vision is the brain, these scientists reason if they can somehow ``bypass'' the eye's normal function and get a visual signal directly to the brain, the person will be able to ``see.''
Scientists working on artificial vision fall into two schools, with both working on implant devices. Surgeons like de Juan and his colleagues at Johns Hopkins are attempting to implant an electronic device on the retina that can perform the function of the first few layers of cells.
The other group, which includes scientists like the University of Utah's Norman, wants to implant electrodes directly in the cortex, in the vision centers of the brain.
The retina group has the advantage of having to bypass less of the visual pathway, so it can leave more of the processing of light to the body's natural systems. Their disadvantage is that the retina is such a delicate piece of tissue that implanting a silicon device on its surface will be difficult, especially since the eye moves around so much.
With the brain implants, the situation is reversed.
``You'll have to have a higher stage of processing to get directly to the brain,'' Norman said. But ``the cortex is a bit more robust than the retina.''
Proponents of artificial vision say the techniques may take decades to perfect - although many expect it can become reality as soon as 2010.
But they concede that the real solution to blindness may not come from engineering at all. Other scientists are experimenting with retinal transplants, and still others are studying ways that genes can be triggered to grow cells or even organs.
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|Publication:||Daily News (Los Angeles, CA)|
|Article Type:||Statistical Data Included|
|Date:||Jul 7, 1996|
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