September 25, 2009 1:51 PM PDT

Bionic eye may restore sight to the blind

MIT's prototype retinal implant consists of a flexible substrate, power and data receiving coils, an electrode array, and a stimulator microchip.

(Credit: Shawn Kelly/MIT)

Electronic retinal implants that can help certain visually impaired people see better are getting closer to reality with a new MIT prototype (PDF).

Engineered eyes a la Blade Runner remain a long way off. But by replacing the function of retinal cells, the implants could help provide a degree of basic vision to those afflicted with retinitis pigmentosa or age-related macular degeneration, major causes of blindness.

Users would wear special glasses fitted with a small camera that relays image data to a titanium-encased chip mounted on the outside surface of the eyeball. The chip would then fire an electrode array under the retina to stimulate the optic nerve. The glasses would also wirelessly transmit power to coils surrounding the eyeball.

In this illustration, the glasses transmit data and power to the prosthesis.

(Credit: Boston Retinal Implant Project)

MIT has been working on retinal implants for 20 years as part of the Boston Retinal Implant Project. About 10 years ago, researchers tested the electrodes on six blind patients, who reported seeing cloud-like images when stimulated.

MIT scientists led by John Wyatt, an electrical engineering professor, want to test their new prototype on patients within three years.

The implants have been successfully placed in pigs for as long as 10 months without damage to the electronics, according to MIT.

About 20 teams worldwide are working to realize the dream of eye implants that could work as well as cochlear implants for the hearing-impaired. But the delicate structures of the eye, as well as engineering challenges, have made for slow progress.

"To create a bionic eye is equivalent to trying to create a television as compared with a radio," Nigel Lovell, a professor at the University of New South Wales collaborating with Australian groups to create a bionic eye, says in this video. "It's orders of magnitude more complex."

One issue researchers must tackle is where to place the electrodes. The Australian group would place them on top of the retina, while MIT's approach is to place them beneath the retina. MIT says that reduces the risk of retinal tearing and requires less invasive surgery.

What might early bionic vision look like? Very low-res. Check out this simulation from a research group at the Tokyo Institute of Technology that wants to use cultured neurons on an electrode array to simulate vision in patients where the optic nerve is not intact.

Since retinal devices aim to replace the millions of photoreceptor cells in the eye, a high-resolution retinal prosthesis firing thousands of pixels at video speed will likely be required for near-natural vision. But that could be decades away.

As of mid-July, though, 30 patients worldwide had been implanted with the Argus II retinal implant developed by California-based Second Sight. It features a 60-electrode grid fixed to the retina and has shown limited but promising results so far, as seen in this BBC interview with a blind man who is now able to perceive a white line on the floor and distinguish white socks from black ones.

A new Argus model with a higher electrode count is currently under development.

Crave freelancer Tim Hornyak is the author of "Loving the Machine: The Art and Science of Japanese Robots." He has been writing about Japanese culture and technology for a decade. E-mail Tim.