MIT researchers are working on a retinal implant that could help blind people regain a useful level of vision.
It's designed for sufferers of retinitis pigmentosa and age-related macular degeneration, two of the leading causes of blindness. It won't restore normal vision, but could help blind people get around more easily.
Patients would wear a pair of glasses with a camera that sends images to a microchip attached to the eyeball. The glasses contain a coil that wirelessly transmits power to receiving coils surrounding the eyeball.
When the microchip receives visual information, it activates electrodes that stimulate nerve cells in the areas of the retina corresponding to the features of the visual scene. The electrodes directly activate optical nerves that carry signals to the brain, bypassing the damaged layers of retina.
In previous implants, the electrodes were attached directly to the retina from inside the eye, which carries more risk of damage. In the latest version, the implant is attached to the outside of the eye, and the electrodes are implanted behind the retina.
The team has been working on the implant for 20 years, and hopes to start testing it in blind patients within the next three years. The goal is to produce a chip that can be implanted for at least 10 years.
They've tried it out in Yucatan miniature pigs, which have roughly the same sized eyeballs as humans, purely to determine whether the implants remain functional and safe. So far, the prototypes have been successfully implanted in pigs for up to 10 months.
The researchers hope that once human trials begin and blind patients can offer feedback on what they're seeing, they will learn much more about how to configure the algorithm implemented by the chip to produce useful vision.
Patients have said that what they would like most is the ability to recognize faces. "If they can recognize faces of people in a room, that brings them into the social environment as opposed to sitting there waiting for someone to talk to them," says Shawn Kelly, a researcher in MIT's Research Laboratory for Electronics.
The implant is described in the October issue of IEEE Transactions on Biomedical Engineering.
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