Researchers from Switzerland and Italy have teamed up to develop the OpticSELINE, a device with intraneural electrodes that stimulate the optic nerve with light sensation in the hopes of activating the visual cortex-in other words, restoring the sight of the blind. They reported in an issue of Nature Biomedical Engineering that they had tested the technology with rabbits and it yielded successful results.
At present, technologies for restoring the sight of the blind involve surgical procedures with the use of either prosthetic retinal implants, which is clinically selective, or brain implants that would stimulate the visual cortex, which is a rather risky procedure. This development would have less disadvantages compared to these traditional methods.
The technology developed by the researchers worked by producing phosphenes-rings of light produced putting pressure on the visual cortex. The intraneural electrodes used in the study are stable enough so that they could provide opulent visual information, unlike cuff nerve electrodes, which were used in previous attempts and researches. Physically compared, the cuff nerve electrodes are surgically positioned around the nerve while the intraneural electrodes pierce through the nerve.
In their experiment, the researchers used OpticSELINE, having an array of 12 intraneural electrodes to deliver electric current to the optic nerve. They then measured activity in the visual cortex. After this, they translated the cortical signals read using an algorithm and showed that each electrode creates a specific pattern of cortical activation. This shows selectivity from the side of intraneural simulation of the optic nerve.
Diego Ghezzi, Medtronic Chair in Neuroengineering at the EPFL, explains how much information they can get from the device. "For now, we know that intraneural stimulation has the potential to provide informative visual patterns," he said. "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."
From their study, the OpticSELINE for humans can currently be made of intraneural electrodes, in varying quantities from 48 to 60. And although this is not enough to fully restore one's eyesight, but the researchers say that the visual signals collected can be further engineered to provide a visual aid for working on one's everyday activities.
