Thursday, August 03, 2006

We See the Future Better Than 20/20


Steve Austin had that enviable telescopic squint. Star Trek chief engineer Geordi La Forge saw darkness as daylight with his 24th-century ocular implants. And now it looks like a generation of very real people who have lost their sight are next in line for such seemingly sci-fi vision. "I'm hesitant to use the word 'superpower,'" says Armand R. Tanguay, Jr., an electrical-engineering professor at the University of Southern California who is building the world's first implantable camera for the blind. But if the device works, he says, "a blind person will have abilities you and I don't."

Tanguay's intraocular camera is part of a multimillion-dollar USC effort backed by the U.S. Department of Energy and the National Science Foundation to develop an artificial retina to restore sight to people whose light-sensitive cells have burned out as a result of decay or disease. That's 10 million people. The project is paying off: Six blind volunteers now have an electrode-studded sliver of silicone tacked to one of their retinas. A digital camera mounted to sunglasses feeds images wirelessly to this implant, whose 16 electrodes zap retinal nerves to produce impressions of light in the brain. Although the resolution is crude next to the 100-million-pixel resolution of a healthy eye, the volunteers can distinguish cup from plate, light from dark, and they can tell when someone strolls past on the sidewalk.

"And we can do better," says USC ophthalmology professor Mark Humayun, the surgeon who pioneered retinal implants and now directs the university project. He intends to implant a 60-electrode sensor with nearly four times the resolution of the original by early 2006 and a 256-electrode chip a few years later. His ultimate goal is 1,000 electrodes. "That should allow people to recognize a face and read," Humayun says. He's giving himself less than a decade to do it.

It's no slam-dunk. "Imagine throwing your TV set in the ocean and making it work," says Robert Greenberg, CEO of Second Sight, the California firm that builds the retinal implants. The eye is filled with saltwater that can corrode electrodes. And then there's the fact that humming electronics can sear nerves and blood vessels.

This is why Tanguay's plan to put the camera inside the eye is so bold. The aspirin-size device he's building consists of an aspherical glass lens and a CMOS (complementary metal-oxide semiconductor) sensor--which produces less heat than a conventional CCD (charge-coupled device)--packed in a watertight tube. The camera would sit just behind the pupil, in the small pouch where the eye's crystalline lens normally is. For people with artificial sight, not only would an implantable camera mean no more goofy spy-cam sunglasses, they wouldn't have to sweep their heads constantly to scan their surroundings--that's what the eye does, naturally.

Tanguay says his camera's three-millimeter focal length will make objects appear crisp no matter how far or close they are, something even the eye can't manage. And he could use a sensor tuned to infrared light, the basis for night-vision scopes, so blind people could see in the dark. One of his colleagues, biomedical engineer James Weiland, prefers the Bionic Man archetype. "You could hook our system up to an electron microscope and give someone super vision," he says. He's only half joking.


German neurologist 0tfrid Foerster electrically stimulates the visual cortex of a human volunteer's brain, causing his subject to "see" small points of light.

Giles S. Brindley of the University of Cambridge implants 80 electrodes under the scalp of a 52-year-old woman who had gone blind. When he applies electricity, the woman sees spots of light.

Armand Tanguay and his colleague Noelle Stiles conduct the first experiment to implant a digital camera in an eye, replacing a dog's natural lens with a glass lens and a sensor.

USC researchers conduct the first human trial of an implantable digital camera connected to a 256-electrode retinal implant.

The introduction of n 1,000-eleclrode implant allows blind volunteers to recognize faces and read half-inch type for the first time.

An external microprocessor encodes images from the interocular camera into a form suitable for the electrode array. Leaving heat-generating electronics outside the body prevents damage to sensitive nerves and vessels.

The electrode array is fixed to the retina with a single tack through the sclera, the eye's tough white rind. Each platinum electrode stimulates nearby nerve cells to produce a localized sensation of light. Simulations show that this 256-electrode array could allow blind subjects to see large objects.

A seven-by-four-millimeter camera with a light sensor, implanted in the eye, wirelessly beams an image to a small digital image processor outside the body. Once processed, the image is transmitted back to the internal antenna and fed via cable to an electrode array mounted on the retina, stimulating the nerves to produce sight.

By: Stroh, Michael, Popular Science

Wednesday, August 02, 2006

Waking up that lazy eye

In amblyopia-"lazy eye"-the brain prefers images from one eye over the other. Most doctors treat the condition in children by patching the good eye for part of each day, but assume that the practice doesn't work past age 10. Some doctors give up on patching at age 7.

A U.S.-Canadian study now finds that children up to age 17 can make significant gains in vision by wearing a patch.

Researchers identified 507 children with amblyopia and randomly assigned half of them to wear a patch from 2 to 6 hours a day for 24 weeks. If needed, the kids also received prescriptions for eyeglasses. All the children were between 7 and 17 years old.

Children ages 7 to 12 who wore patches were four times as likely as those who didn't to improve their vision in the weak eye by two rows on the standard 11-line eye chart that doctors use to assess eyesight, the scientists report in the April Archives of Ophthalmology. Kids with amblyopia usually have a lazy eye that reads down to only the middle of the chart. People with normal vision see down to about the 10th row.

Children 13 to 17 also gained some visual clarity by wearing a patch, but only if they hadn't received such therapy earlier in their lives. Their gains were smaller than those of 7-to-12-year-olds but still significant, says study coauthor Richard W. Hertle of the University of Pittsburgh.

Long-term follow-up might reveal whether the vision improvements are permanent, Hertle says.

By: N. S., Science News