New Device May Help People Blinded by Certain Conditions
WebMD News Archive
March 6, 2000 (Baltimore) -- In November 1999, Stevie Wonder told the
congregation at a Detroit church that an implantable computer chip might help
him to see for the first time in his life. Intense media attention was then
focused on Johns Hopkins researchers, who are developing and testing a device
called a retinal chip. "We think we will have an implant for use in humans
in about five years," says Gislin Dagnelie, PhD, assistant professor of
ophthalmology at Hopkins and one of the researchers on the project.
Unfortunately for Mr. Wonder, the retinal chip is limited to use in people
who are blinded due to diseases such as retinitis pigmentosa, in which a
patient's visual field gets progressively smaller, and macular
Dagnelie tells WebMD, "This technology is really only appropriate for
persons who have had sight at some time, because it depends upon correct
interpretation of the visual signal by the brain." He says it also requires
that the portion of the brain that processes visual information be
functioning." Wonder lost his vision shortly after birth.
The retinal chip is a very small array of electrodes that would be implanted
in a person's eye. The chip converts visual information coming in through the
pupil to signals that are then transmitted to other cells in the eye, and from
there to the brain. The result would be a pattern in shades of white, black,
and gray. Initial tests using a version of this chip have demonstrated that
patients can recognize simple patterns or follow a light.
"The electrodes we want to use now are actually a bit different,"
says Dagnelie. "They are under development by a California company, which
is filing the investigational device approval with the FDA. Once they are
approved, we will use them in a strain of Irish setter dogs, which develop a
condition quite similar to retinitis pigmentosa but with a much quicker time
course. It's gratifying to think that the work we do with these animals will
actually improve their lives."
In separate research, the National Institutes of Health (NIH) is working to
use a different part of the brain to enable patients to have enough vision to
get around more easily. William Heetderks, MD, NIH program director for neural
prostheses at NIH, says, "Visual prostheses have the potential to be quite
practical and to vastly improve life for a large number of people."