Visual prosthesis simulator offers a glimpse into the future

Key Takeaways

  • Researchers have developed an open-source visual prosthesis simulator to help improve research into visual prostheses.
  • The simulator may also be used to give people an idea of the type of vision possible with current and future 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, 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 cerebral cortex. In this case, a prosthesis converts camera input into electrical stimulation by way of electrodes implanted in the cerebral cortex. The electrodes stimulate the surrounding tissue with weak electrical currents, generating tiny points of light known as ‘phosphenes’. In doing so, the prosthesis bypasses part of the affected visual system and thus allows some form of vision. You could compare it with a matrix sign along the highway, where individual lights form a combined image.

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 visual 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 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