Is an artificial retina a potential cure for blindness? Could it function safely in a human eye? These are among the questions asked, and answered, in an article in the summer issue of Stanford Medicine magazine.
The piece, called "Bionic," examines the current state of visual prosthetics through the lens of the work of two Stanford scientists: Daniel Palanker, PhD, shown in the photo at right, and E.J. Chichilnisky, PhD. Palanker's team is developing a device in partnership with Pixium Vision of France. As writer Theresa Johnston explains:
...it features a tiny video camera mounted atop futuristic-looking augmented reality goggles, connected to a video processor about the size of a cell phone... It relies on multiple arrays of photodiodes, each about a millimeter in diameter and containing hundreds of pixels, which work like the solar panels on a rooftop. Surgeons can lay down these tiny chips, like tiles, replacing the missing light-sensitive rods and cones in the central retina.
When PRIMA’s camera captures an image of, say, a flower, the video processor transmits that picture to a microdisplay mounted inside the goggles. Powerful pulses of near-infrared light illuminate this display and are projected from the goggles into the eye, like the invisible rays of a TV remote control. The implanted photodiodes pick up these signals and convert them into tiny pulses of electrical current, which stimulate the bipolar cells directly above them. The signals propagate to the ganglion cells and then to the brain, which perceives them as patterns of light: a flower!
Human clinical trials will start later this year in Europe, Palanker said.
Chichilnisky, who works near Palanker and often joins him to talk shop, is taking a different approach: He's figuring out how to cue specific cells in the retina, replicating the precise vision of a functioning eye. "I'm not saying we've got it nailed, but we certainly now have proof of concept for how to make a better device in the future," he said.
His current challenge is moving their current work onto an electrode array that can function safely in the eye. Trials in animals could begin within five years, Chichilnisky said.
Previously: Stanford Medicine magazine reports on the future of vision and New retinal implant could restore sight
Photo by Brian Smale