Researchers from Switzerland and Italy are developing a new technology with which blind people can benefit in everyday life. Using the intraneural OpticSELINE electrode, messages and signals are to be transmitted past the eyeball and directly into the brain. Previously, the scientists successfully tested the technology on rabbits.
Silvestro Micecra, the study co-author explained that “intraneural stimulation can be a valuable solution for many different neuroprosthetic devices to restore sensory and motor skills". At present, it is estimated that some 39 million people worldwide are affected by blindness.
There are different approaches to producing phosphenes without seeing light directly. Retinal implants, for example, are often unsuitable for many patients. Although half a million people are blind due to retinitis pigmentosa, only a few hundred are suitable for retinal transplantation for clinical reasons. Brain implants that directly stimulate the visual cortex are also a risky method. The new research approach minimizes the exclusion criteria because most people with visual impairment have intact optic nerves and brain nerve tracts.
Therefore, intraneural electrodes may be the solution to transmit visual information to patients. According to the researchers, these electrodes are also more stable and move less than electrodes in earlier research approaches because they penetrate directly through the nerve.
The Italian and Swiss scientists jointly developed the OpticSELINE, a collection of 12 different electrodes. In order to test how effective these electrodes are, the researchers transmitted current to the optical nerve via OpticSELINE and measured brain activity in the visual cortex. The team developed an algorithm for decoding the cortical signals. They found that each individual stimulating electrode produces unique patterns in brain activity.
Diego Ghezzi, another study co-author commented on the impact this technology can have: "To our knowledge, intraneural stimulation has the potential to transmit informative optical patterns. Of course, we also rely on patient feedback in future clinical trials to refine these patterns. But from a purely technical perspective, clinical trials could start tomorrow."
According to the current state of electrode technology, OpticSELENE could contain 48 to 60 electrodes in humans. This limited number of electrodes is not yet sufficient to fully restore vision, but researchers believe it is sufficient to provide clear visual support in everyday life.
Vivien Gaillet, Annarita Cutrone, Fiorenzo Artoni, Paola Vagni, Ariastity Mega Pratiwi, Sandra Alejandra Romero, Dario Lipucci Di Paola, Silvestro Micera & Diego Ghezzi. Spatially selective activation of the visual cortex via intraneural stimulation or the optic nerve. Nature Biomedical Engineering, 2019 DOI: 10,1038/s41551-019-0446-8