From Darkness to Light: Giving Sight to the Blind
When the camera sends a video signal to the small processor, the image is streamlined, says Dagnelie. "It basically pares the image down to the most important components, like edges and contrast -- so a person can see the outlines of a face, see a doorway, obstacles in their path, things like that. We think it will be a while before it's good enough that they can recognize faces with this, but they will be able to distinguish faces."
In preliminary tests involving six patients -- performed under local anesthesia, so patients could report what they were seeing -- Dagnelie and colleagues first showed them one or two dots, then as many as 25 dots in a 5- by 5-inch square, then one letter at a time," he tells WebMD. The images they see are very crude, he adds. "Think of this as a stadium scoreboard, but just a tiny little corner of it made up of big crude dots. It corresponds to about 20/2000 vision -- really primitive."
"We expect that the first implants will be similar to that. It will tell them something about obstacles, enough to get around, enough to see where a person is sitting," Dagnelie tells WebMD. "To a blind person, that can be a whole lot. And as the technology gets better and as we get better at implanting it ... the image will get finer, and we'll be able to get better resolution. But this is a start."
Within three to five years, Dagnelie says, he expects patients to have long-term implants that will help them operate more independently. "I expect people will be able to distinguish big letters, possibly read a label or a short piece of text. [But] they won't be able sit down and read a newspaper, at least not in the near future."
Another version of a bionic eye being developed by Optobionics in Chicago integrates all components into one chip implanted below the retina of the eye; it's called the Artificial Silicon Retina. "The design of our chip is relatively simple and may be able to function solely with the power provided by light entering the eye," says Vincent Chow, an engineer who co-founded Optobionics Corporation.
"Presently, our chip does not require connecting wires, batteries, or other [outside] devices," says Chow. "The artificial silicon retina is made up of thousands of microscopic solar cells that convert light into electrical impulses and is capable of electrically stimulating [the] remaining cells in the retina when implanted [into the eye]."
"What a patient sees will greatly depend on how the microscopic solar cells on the chip interact with the remaining functional retinal cells," Chow tells WebMD.
This summer, three patients received implants as part of the first multimonth study of any retinal implant. While Chow declines to report the degree of vision patients have experienced, he says that there have been no signs of rejection or other complications, and that preliminary results will be announced soon. Chow invented the artificial silicon retina with his brother, Alan Y. Chow, MD, a visiting professor at the University of Illinois in Chicago and clinical assistant professor of ophthalmology at Tulane University Medical Center in New Orleans.