Learning to See: New Technology for the Blind

By: Loren Elmann  |  September 19, 2019

Science and Technology

By: Loren Elmann, Contributing Writer

Scientists from EPFL in Switzerland and Scuola Superiore Sant’Anna in Italy are in the process of developing new technology for the blind. It involves using OpticSELINE, a new intraneural electrode created to stimulate the optic nerve by piercing through it. This technology’s recent successful testing in rabbits has the potential to aid the permanently blind.

Though the development of technology for the blind is not a new concept, the existing technology is insufficient due to its exclusion criteria. For instance, while retinal implants — a prosthetic device — can aid the permanently blind, the exclusion criteria would be receiving them. 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. Another possible aid is a brain implant that stimulates the visual cortex. However, undergoing this procedure is very risky, and not everyone is willing to take the risk. The advantage of OpticSELINE, the new intraneural solution, is that it reduces exclusion criteria because the optic nerve and the pathway to the brain are usually intact.

Scientists have been attempting to stimulate the optic nerve since the 1990s, but they have only now become successful in doing so, because as Diego Ghezzi, EPFL’s Medtronic Chair in Neuroengineering, explains, “Back then, they used cuff nerve electrodes. The problem is that these electrodes are rigid and they move around, so the electrical stimulation of the nerve fibers becomes unstable. The patients had a difficult time interpreting the stimulation because they kept on seeing something different. Moreover, they probably have limited selectivity because they recruited superficial fibers.” Intraneural electrodes are more likely to bring about successful results because they are more stable and directly pierce through the nerve instead of being surgically placed around it. 

To test the intraneural electrodes’ effectiveness at stimulating the nerve fibers within the optic nerve, Ghezzi’s team delivered electric current to the nerve via OpticSELINE, an electrode array of twelve electrodes. Then, when they measured the brain’s activity in the visual cortex, they discovered that each stimulating electrode induced a specific and unique pattern of cortical activation. Essentially, the intraneural stimulation of the optic nerve is successfully selective and informative. 

One must keep in mind, however, that this technology is not yet a guaranteed fix because the visual perception behind the cortical patterns remains unknown and the current electrode technology of OpticSELINE can consist of up to 48-60 electrodes, which is not sufficient to restore sight entirely. So, as Ghezzi said, “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.” This major improvement to obtain limited visual signals can conceivably be engineered to provide a visual aid for the blind in the near future.