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High-Tech Implants Restore Limited Vision and Mobility


Sooner or later, it seems, most everything imagined in science fiction comes true. From flying in space to talking on a telephone without wires, today's science increasingly resembles yesterday's fiction. And that's becoming more and more true in medicine.

In the 1970s, you may have followed the thrilling story of astronaut Steve Austin as doctors rebuilt his shattered body after that terrible accident.

OK, it was a TV series called The Six Million Dollar Man. Steve Austin, played by Lee Majors, got bionic implants that gave him strength, speed and vision far beyond normal capabilities.

Three decades later, science is catching up.

For example, one of the leading causes of blindness among older adults is macular degeneration, and there is no cure.

The condition affects the retina, the light-sensitive part of the back of the eyeball. So why not bypass that area and hook up a camera directly to the optic nerve?

"What we're trying to do is to take real-time images from a camera, convert them into tiny electrical pulses that would jump-start the otherwise-blind eye and allow patients to see," says Mark Humayun of the University of Southern California. He's developed a device that includes a tiny camera, placed discretely on a pair of eyeglasses, that sends images to a receiver that is actually implanted inside the eye. Humayun says six patients have been using the device for as long as five years. Even with only 16 pixels, the patients report a surprising increase in their visual capabilities.

"We expected that all we would see is just light and dark," he explained, "but the subjects can differentiate in a test environment between a cup, plate, and a knife. They can tell motion around there, they can tell large objects so they don't stumble into them, and this is all very surprising because it's not what we expected, and again it really speaks to the brain's ability to be able to fill in a lot of the missing information."

The researchers are now working on a 60-pixel version, which they hope will give even better results.

Humayun was one of several researchers working on restoring functions lost to age, accident or war who discussed their work at the recent annual meeting of the American Association for the Advancement of Science, the AAAS. Another was Roger Narayan of the University of North Carolina.

"There's a current demand by patients and clinicians for devices that fit patient geometry, specific patient conditions," Narayan told reporters. "So the idea is to use novel materials - whether it be ceramics, polymers or metals - and novel, rapid-prototyping technologies to create devices that fit the particular patient."

Narayan said such custom treatments can help, whether the patient is a soldier being fitted with an artificial leg or a child with a congenital deformity.

For those of us at the AAAS meeting, nothing was more impressive than the demonstration given by Jennifer French. She's not a scientist. She's a young woman sitting in a wheelchair, paralyzed from a snowboarding accident. She presses a button on a control box strapped to her waist ... and then she stands up.

"So here you see the functional benefit and the fact that I can stand out of my wheelchair," she explained. "I can reach for things I usually can't reach. I can move around into spaces where the wheelchair wouldn't fit. And I can transfer onto spaces that I normally wouldn't be able to transfer onto."

In the case of a spinal cord injury like Jennifer French's, the leg muscles, for example, aren't damaged. They just don't receive a signal from the brain telling them what to do. The system developed by Hunter Peckham and colleagues at Case Western Reserve University bypasses the injured part of the nervous system and applies an electrical stimulation to replicate the signal that the muscles no longer receive. But the artificial system takes some getting used to.

"There is a distinct learning curve," French explained. "Because when ...[you] press the button, there's a three-second delay, you stand and there's another three-second delay, where it's fully implanted so you have to get your timing down of how it works. And that's what you really need to work on, because there is a learning curve."

There are real benefits to a system like this, which is still very experimental. There's less risk of medical complications from being in a wheelchair all day, and of course there's an enormous psychological boost. Jennifer French was married a few years ago. Like many American brides, she wanted to walk down the aisle at her wedding, not roll down in a wheelchair. And two years after she got her implant system, despite the spinal cord injury that put her in a wheelchair, that's exactly what she did.

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