Smart Glasses could help blind people regain some vision in the future.
It does seem like the stuff of miracles or science fiction to be able to help blind people see again. It has always been one of the most challenging tasks for scientists. Diego Ghezzi, the Medtronic Chair in Neuroengineering (LNE) at EPFL’s School of Engineering, has focused his research on this subject. He and his team have been working on a retinal implant that uses camera-equipped smart glasses and a microcomputer since 2015.
“Our system is designed to give blind people a form of artificial vision by using electrodes to stimulate their retinal cells,” Ghezzi explains.
The smart glasses’ sensor records pictures in the wearer’s field of view and transfers the information to a microcomputer embedded in one of the eyeglasses’ end-pieces. The data is converted into light signals by the microcomputer, which is then transferred to electrodes in the retinal implant. The electrodes then activate the retina, resulting in a simplified black-and-white version of the scene being seen by the wearer. As the retinal cells are stimulated, spots of light appear in this condensed version. Wearers must, however, learn to distinguish the multiple dots of light in order to identify shapes and objects.
“You can learn to identify unique constellations by looking at the stars in the night sky. In our system, blind patients can see something similar, “Ghezzi explains.
The device has not yet been checked on humans, which is the only drawback. The study team must first be confident in their findings. “We aren’t yet authorized to implant our device in human patients since obtaining the medical approval takes a long time. But we came up with a process for testing it virtually — a type of work-around,” Ghezzi explains. Engineers created a virtual reality software that can replicate what patients would see if the implants were used. Their results were recently published in the journal Communication Materials.
Vision is measured using two parameters: area of vision and resolution. As a result, the engineers evaluated their device using the same two criteria. They created retinal implants with 10,500 electrodes, each of which generates a single dot of light. “We weren’t sure if this would be too many electrodes or not enough. We had to find just the right number so that the reproduced image doesn’t become too hard to make out. The dots have to be far enough apart that patients can distinguish two of them close to each other, but there has to be enough of them to provide sufficient image resolution,” Ghezzi explains.
The engineers also had to ensure that each electrode could emit a dot of light consistently. Ghezzi clarifies: “We wanted to make sure that two electrodes don’t stimulate the same part of the retina. So we carried out electrophysiological tests that involved recording the activity of retinal ganglion cells. And the results confirmed that each electrode does indeed activate a different part of the retina.”
The next move was to see if a resolution of 10,500 light dots was adequate, which is where the virtual reality program comes in. “Our simulations showed that the chosen number of dots, and therefore of electrodes, works well. Using any more wouldn’t deliver any real benefits to patients in terms of definition,” Ghezzi explains.
Engineers also ran experiments of the exact resolution but different field-of-view angles. “We started at five degrees and opened up the field all the way to 45 degrees. We found that the saturation point is 35 degrees — the object remains stable beyond that point,” Ghezzi explains. These tests showed that the system’s capability does not need to be increased anymore and that it is ready for clinical trials. However, the team will have to wait a bit while before their technology can be used on real people. For the time being, returning vision is a science fiction concept.
