The electrode array implanted directly onto the retina.
(Credit: Second Sight)
An electrode array placed in a blind test subject's eye has allowed researchers to transfer Braille patterns directly to the retina.
Usually paired with goggles mounted with a video camera, the Argus II Retina Prosthesis by Second Sight transforms a visual scene into a series of electrical pulses. These are transferred wirelessly to a grid of 60 electrodes implanted directly onto the subject's retina — conveying that information to the brain, so that the subject can "see" what is in front of them.
The array has already entered clinical trial, with 30 test subjects displaying a marked improvement in perceiving the world around them.
In this latest experiment, Second Sight researchers have bypassed the camera, sending a signal directly into the eye of a single test subject via computer, and lighting up Braille codes in a 6x2 array of electrodes in the grid.
Firstly, single letters were stimulated, followed by short two- to four-letter words. The subject had a success rate of 89 per cent for the single letters, 80 per cent for two-letter words, 60 per cent for three-letter words and 70 per cent for four-letter words.
Although subjects in the clinical trial were correctly able to identify letters on a page, this solution would be much better for those patients who, blind from birth or a very young age, know no other system but Braille.