The scientists from École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland and Scuola Superiore Sant’Anna in Italy are developing a technology that can completely bypass the eyeball and send messages directly to the brain to restore vision to the blind. They will be doing this by stimulating the optic nerve with intraneural electrode known as OpticSELINE.
The study was published in the journal ‘Nature Biomedical Engineering’. The new technology has been successfully tested in rabbits and could pave the way for a new visual aid for daily living. “We believe that intraneural stimulation can be a valuable solution for several neuroprosthetic devices for sensory and motor function restoration. The translational potentials of this approach are indeed extremely promising,” explains Silvestro Micera, a professor of Bioelectronics at Scuola Superiore Sant’Anna.
Blindness is estimated to affect 39 million people across the world. Various factors such as genetics, retinal detachment, trauma, stroke in the visual cortex, glaucoma, cataract, inflammation or infection can induce blindness. While some blindness is temporary and can be medically treated, at present there is no major solution to permanent blindness.
The new concept is to produce phosphenes, the sensation of seeing light in the form of white patterns, without seeing light directly. Retinal implants, a prosthetic device for helping the blind, suffer from exclusion criteria. For example, half a million people worldwide are blind due to Retinitis pigmentosa, a genetic disorder, but only a few hundred patients qualify for retinal implants for clinical reasons. A brain implant that stimulates the visual cortex directly is another strategy even though risky. The new intraneural solution minimizes exclusion criteria since the optic nerve and the pathway to the brain are often intact.
The team engineered the OpticSELINE, an electrode array of 12 electrodes. To understand how effective these electrodes are at stimulating the various nerve fibres within the optic nerve, the scientists delivered electric current to the optic nerve via OpticSELINE and measured the brain’s activity in the visual cortex. They showed that each stimulating electrode induces a specific and unique pattern of cortical activation, suggesting that intraneural stimulation of the optic nerve is selective and informative.
With current electrode technology, a human OpticSELINE could consist of up to 48-60 electrodes. This limited number of electrodes is not sufficient to restore sight entirely.  But these limited visual signals could be engineered to provide a visual aid for daily living.
According to EPFL’s Medtronic Chair in Neuroengineering Diego Ghezzi “For now, we know that intraneural stimulation has the potential to provide informative visual patterns. It will take feedback from patients in future clinical trials to fine-tune those patterns. From a purely technological perspective, we could do clinical trials tomorrow.”

Source: Science Daily, The Week, Times Now, Indian Express.
https://www.nature.com/articles/s41551-019-0446-8

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