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Scientists develop implant to restore sight by stimulating the optic nerve

OpticSELINE electrode array for intraneural stimulation of the optic nerve. EPFL/Alain Herzog

Blindness is difficult to treat, in part because it can be caused by so many different issues in the eye, the brain, or the optic nerve connecting the two. But recently, scientists from the Swiss Federal Institute of Technology (EPFL) have developed a technology to directly stimulate the optic nerve, which could be used to restore people’s sight in the future.

Previously, researchers have found ways to restore sight by using a camera to capture images and then beam the images to a microchip implanted in the retina, but this requires a fully functioning optic nerve. A different technology bypasses the optic nerve and inputs images directly to the brain, but this system only allows people to see very basic images.

The new technology uses aspects of both of these technologies in that it bypasses the eye and sends information to the brain directly. The development is that the optic nerve itself is stimulated using an implant. The advantage of this approach is that it can be used on a much larger range of people.

“We believe that intraneural stimulation can be a valuable solution for several neuroprosthetic devices for sensory and motor function restoration,” Silvestro Micera, EPFL’s Bertarelli Foundation Chair in Translational Neuroengineering, said in a statement. “The translational potentials of this approach are indeed extremely promising.”

The device developed to stimulate the optic nerve, called OpticSELINE, is an array of 12 electrodes that deliver an electric current. To test how well the implant stimulated the optic nerve, the scientists used it to deliver a current and looked at activity in the brain’s visual cortex. By developing an algorithm to decode the signals from the brain, they could see that each electrode created a unique pattern of activation in the brain. This means that in principle the optic nerve can be stimulated in specific ways to send visual information to the brain.

To make the technology pragmatic, more electrodes will be required. With current technology, between 48 and 60 electrodes could be contained in an OpticSELINE device. This isn’t enough to fully restore sight but could be used to give back some degree of vision to make blind people’s day to day lives easier.

“For now, we know that intraneural stimulation has the potential to provide informative visual patterns,” EPFL’s Medtronic Chair in Neuroengineering Diego Ghezzi said in the same statement. “It will take feedback from patients in future clinical trials in order to fine-tune those patterns. From a purely technological perspective, we could do clinical trials tomorrow.”

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