Blind World

Artificial vision getting trial run in human cases.

September 1, 2003.


Connie Schoeman began losing her vision in 1957 and is now blind. But since doctors placed a thin strip of electronics onto the back of her right eye in March, she has seen spots of light and bright shapes.

The type of vision being experienced by Schoeman, 76, might be remembered one day as a giant step forward for the blind. After years of research and laboratory prototypes, artificial vision now is being extensively tested in humans for the first time. During the past two years, 26 people in the United States and Europe have received a variety of experimental implants, and more surgeries are planned.

The vision produced by these devices ó designed to stimulate nerves in the optical system or brain ó is extremely crude and not a cure for blindness. Many vision specialists worry that the efforts could provide false hope to the 45 million people worldwide, including 1.3 million Americans, who are legally blind. Nevertheless, recent experiments suggest that within 10 years commercial electronic implants could help some blind people navigate and perform daily activities.

In weekly training sessions conducted recently at the University of Southern Californiaís Doheny Eye Institute, Schoeman used a camera connected to the "artificial retina" in her eye to distinguish a white plate from a plastic knife.

It just looks like a number of lights. If itís real skinny, I know itís the knife, "said Schoeman, who began losing her sight when she was 29 because of retinitis pigmentosa, a disease that progressively kills retina cells but leaves the rest of the visual system intact.

In its simplest form, vision is produced when light entering the eye is turned into electrical signals that are carried by the optic nerve to the brainís visual cortex. When that circuit is broken, blindness results. The idea of artificial vision is to replace the broken circuit with electronics ó including pinhole cameras, computer chips and electrodes wired to the nervous system.

The bionic devices tested so far include both those attached to the back of the eye itself and those implanted directly in the brain. Patients with both types of implants describe seeing multiple points of light and, in some cases, crude outlines of objects.

One U.S. researcher, William Dobelle, recently reintroduced a brain implant, a form of which was first tested in the late 1960s. Although his approach has drawbacks ó it requires large electrical currents that could prove dangerous ó some patients have eagerly paid to have the surgery done. Many scientists believe that brain implants ultimately will produce highly useful vision, but only when they become far more sophisticated devices that can communicate with individual neurons within the brain, a prospect that remains distant.

Placing electrodes in the eye has proved easier. During the past decade, work on these retinal implants has attracted growing government funding and commercial interest. Such implants zap electrical signals to nerves on the back of the eye, which then carry them to the brain. However, since these devices take advantage of surviving parts of the eye they will help only the subset of blind people whose blindness is due to retinal disease, by some estimates about 30 percent of the blind. Moreover, scientists donít believe any implant could help those blind since birth, because their brains never have learned to recognize vision.

A half-dozen companies in the United States, Japan and Europe are developing vision implants. Optobionics Inc., a Naperville, Ill., startup, has implanted 10 people with an artificial retina under safety tests approved by the Food and Drug Administration. Second Sight Medical Products Inc. of Sylmar, Calif., built the artificial retina that ophthalmologists at the university surgically implanted into the eyes of Schoeman and two other volunteers.

The National Institutes of Health is spending $12.5 million over five years to support Second Sight and its academic partners. Entrepreneurs in Germany have recently started two companies ó Retina Implant AG of Tubingen and IIP-Technologies GmbH, in Bonn. IIP is recruiting 20 volunteers for tests of its artificial retina design in Germany and at a clinic in Vienna. The German government has spent roughly 10 million euros ó about $10.9 million ó during the past several years to kickstart artificial-vision research in that country.

Artificial-vision researchers take inspiration from another device, the cochlear implant, which has successfully restored hearing to thousands of deaf people. But the human-vision system is far more complicated than that of hearing. The eye perceives millions of distinct points of light. Light entering through the pupil is converted to electrical signals by anatomical rods and cones, the light-sensitive cells in the retina. Those electrical pulses are carried through the optic nerve to the brain, where they yield images of the world.

By contrast, the retinal implant in use at the university is designed to yield just 16 points of light, by way of a grid of electrodes surgically attached to the retina. Mark Humayun and Eugene de Juan, the ophthalmologists who pioneered the device, also implanted a small computer chip and battery behind Schoemanís ear. The chip conveys signals from a camera mounted on a pair of glasses to the implantís electrodes. The electrodes stimulate the retina, which conveys the signal through the optic nerve to the brain.

Since the implantís electrodes fill in only for lost retina cells, the technique wonít work for those born blind or who have lost their eyes. Humayun said he explained that to musician Stevie Wonder, who approached the universityís team in 1999 after word of progress with vision implants stirred the hopes of the blind.

The simple images patients see are produced by turning on different combinations of the 16 electrodes. One of Humayunís patients is able to make out a foot-high letter U from a letter H from a few feet away after scanning the letters for about 15 seconds.

Itís not yet certain what level of vision will prove useful for the blind. Researchers say that to produce a simple rendering of a face, more than 600 electrodes will be needed. (Researchers hope someday to create implants with 1,000 electrodes.)

The university researchers now are performing tests on dogs of an implant with 60 electrodes. Second Sight founder Alfred Mann, who also runs a company selling cochlear implants, said he thinks the 60-electrode device could be on the market within five years.

Bob Greenberg, president and chief executive of Second Sight, said," Our expectation is that even these crude devices may help with mobility ó to see a door or a chair. The kind of resolution we are seeing in the clinic suggests it may help with tasks of daily living. "

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