Researchers transmit braille directly to the retina of blind test subject
By Ben Coxworth
November 23, 2012
Second Sight’s Argus II Retinal Prosthesis is definitely an interesting piece of technology, allowing a blind user to “see” objects, colors and movement in their environment. Ordinarily, this is done with the help of a video-camera-equipped pair of glasses worn by the user. In a recent experiment, however, researchers bypassed the camera, transmitting visual braille patterns directly to a blind test subject’s retina.
Here’s how the Argus II normally works. The prosthesis itself is implanted in a blind user’s eye, placing an array of 60 electrodes against the surface of the retina. The accompanying video glasses take in the view in front of the user, and convert the video signal into electrical pulses. These pulses are wirelessly transmitted to the implanted electrodes, which respond by selectively stimulating retinal nerve cells.
While the results aren’t the same as normal vision, they’re good enough to allow some users to identify individual printed letters.
In a recent experiment, six of the electrodes within a single test subject’s implant were selectively activated without the use of the camera. By selecting different patterns of electrodes, the researchers could form different visual patterns that represented specific braille characters – each electrode represented one of the bumps that makes up part of a braille character, which would ordinarily be felt with the fingers instead of being seen.
The test subject saw each character for half a second, and was shown isolated individual characters along with words up to four letters long, made from a sequence of characters. They had an 89 percent success rate in identifying the individual characters, and up to 80 percent for short words.
If some Argus II recipients can already discern regular letters, though, what would be the point in being able to see braille? For many users, it would likely allow them to read considerably faster than is currently possible with the prosthesis’ letter-visualizing capabilities.
A Second Sight research scientist told us that the braille feature may be added to the Argus II software at some point in the future, and would not involve changing the existing device or its functionality.
A paper on the experiment was published this week in the journal Frontiers in Neuroprosthetics.
Source: Second Sight