Visual prosthesis simulator offers a glimpse of the future 

Key Takeaways

  • Researchers have developed a visual prosthesis simulator to simulate the vision that might be possible for a blind person implanted with a cortical visual prosthesis. 
  • The simulator can be used to simulate both the state of the art and what the future may hold for cortical visual prostheses. 

Blindness affects approximately forty million people worldwide and is expected to become increasingly common in the coming years. Patients with a damaged visual system can be broadly divided into two groups: those in whom the damage is located in front of or in the light-sensing photoreceptors of the retina and those, like glaucoma patients, in whom the damage is further along in the visual system. 

Various retinal prostheses, implantable electronic devices designed to stimulate a sensation of vision in the eyes of blind individuals, have been developed for the first group of patients in recent years, and clinical tests are underway. The problems for the second group are more difficult to tackle.

A potential solution for these patients is to stimulate the visual center of the brain rather than the eye. A cortical visual prosthesis converts camera input into electrical stimulation of the cerebral cortex. By implanting electrodes in the brain’s visual cortex and stimulating the surrounding tissue with weak electrical currents, tiny points of light known as ‘phosphenes’ can be generated. These phosphenes can be used to form an image, much like with a matrix sign along the highway, where individual lights form a combined image. In doing so, a cortical visual prosthesis bypasses part of the affected visual system and thus allows some form of vision. 

How we can ensure that such an implant can actually be used to navigate the street or read text remains an important question. Thus, in collaboration with their colleagues at the Donders Institute, researchers at the Netherlands Institute for Neuroscience have developed a simulator that enables artificial vision observations for research into visual prostheses. This open-source tool is available to researchers and offers those who are interested an insight into future applications. The study is published in the journal eLife.

Researcher Maureen van der Grinten said, “Instead of waiting until blind people have received implants, we’re trying to simulate the situation based on the knowledge we have. We can use that as a basis to see how many points of light people need to find a door, for example. We call this ‘simulated phosphene vision’.” “To make our simulation more realistic, we collected a whole load of literature, created and validated models, and looked at the extent to which the results correspond to the effects that people reported. It turns out that the dots vary greatly in shape and size depending on the parameters used in the [cortical] stimulation.”

“We are now also using the simulator to give people an idea of where this research could go and what to expect when the first treatments are carried out in a few years. Using VR glasses, we can simulate the current situation with 100 electrodes, which also highlights how limited vision through a prosthesis is: they may be able to find a door but won’t have the ability to recognize facial expressions. Alternatively, we can show a situation with tens of thousands of electrodes and what that will bring us when this technology is developed far enough.”

Source: Netherlands Institute for Neuroscience, Medical Xpress, February 27, 2024; see source article