Prosthetic retina restores partial sight to blind mice

A prosthetic device consisting of a camera, encoder and stimulator sent electric signals to the brain and helped restore partial sight in blind mice, aided by an injection of a special gene. Researchers at Weill Cornell Medical College in New York made this happen by deciphering the code that mouse retinas use to talk to the brain and then mimicking that same process with the device.

While the research is very early-stage, the discovery described in detail in the Proceedings of the National Academy of Sciences may allow researchers to develop a viable prosthesis for humans with degenerative eye diseases, well beyond technology now in use (including implanted electrodes) that has generated limited benefit. Picture an enhanced pair of glasses, essentially. The latest breakthrough is generating significant attention, with informative coverage in Bloomberg and Nature, among other publications. And it is a less invasive approach, potentially than what Second Sight Medical Products is trying. The company expects to make its case before an FDA panel of experts Sept. 28 for a prosthesis system that would use a patient's glasses to convert video images into electrical impulses. Those are transmitted wirelessly to electrodes implanted onto the retina's surface to help the patient see.

Physiologist Sheila Nirenberg and her student, Chethan Pandarinath, developed the technology. To prepare the mice, they first turned to algae, of all things--wanting to harness a light-sensitive protein the plant produces. The team engineered a virus to carry a special gene that produces the protein and injected it into the retina nerve cells of the blind mice. After researchers shined light into the rodents' eyes, the protein went to work, causing the diseased retina nerve cells to signal the brain as they would in healthy eyes.

Next, the team cracked the code used by mouse retinas to talk to the brain and then reproduced it in the prosthetic device. When worn, the prosthesis sent electrical signals to the eye meant to mimic a mouse's normal visual communication. And it did. Retina cells received the code, according to the Bloomberg and Nature stories, and responded by firing electric impulses that the brain would read as "sight." This happened with the mice, which developed a newfound ability to track moving stripes.

We told you this was early-stage, and human trials are likely some time in the future. But the thought is that the technology could help treat macular degeneration and other eye conditions in humans. A prosthetic device for them would include a pair of glasses, small video camera and a microchip, the Nature story notes. The scientists say they want to test the technology on humans within two years, but they first must raise enough funding for clinical trials to enable them to move forward, according to the Bloomberg article.

- read the Bloomberg piece
- consider the Nature story

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