(CN) — A medical device the size and shape of a contact lens could one day facilitate vision in people who are blind. The technology for a prosthetic retinal implant is still in the works, but researchers say they are closer than ever to achieving a feat previously impossible in medicine.
The implant works in tandem with a pair of smart glasses, equipped with a camera, and a microcomputer. Researchers have been developing the device since 2015, and on Friday they published new results in the journal Communications Materials.
"Our system is designed to give blind people a form of artificial vision by using electrodes to stimulate their retinal cells," said Diego Ghezzi, lead author and a researcher at the Swiss Federal Institute of Technology Lausanne, in remarks released with the research.
As the camera in the smart glasses captures images surrounding the person wearing them, it sends information to a microcomputer, also embedded in the glasses. In turn, the tiny computer converts the data into light signals, sending those to the retinal implant’s electrodes.
The person wearing the glasses and retinal implants won’t perceive the world the way a seeing person might; the implant allows them to see a black-and-white version of an image, made out of specks of light that appear when the retina is stimulated.
Ghezzi compared the effect to “when you look at stars in the night sky.”
“You can learn to recognize specific constellations,” the researcher added.
“Blind patients would see something similar with our system."
Three factors make Ghezzi’s system of devices unique, he said in a video describing the implants. For one, photovoltaic cells power the mechanisms, so they can remain cordless — a necessary provision for bringing the technology from the lab into the real world.
Second, a wide-field design “will restore a large field of view,” Ghezzi said. And finally, the implant itself is injectable, making placement within the retina a smoother process.
For now, those features are all future-looking; the device, tested in mice so far, has not yet been approved for trials in humans. That approval process could take a long time, so Ghezzi said his team came up in the meantime with “a type of work-around.”
By engineering a virtual-reality program that simulates what a patient would see while wearing the implants and glasses, they have been able to adjust the field of vision and resolution of the implants to improve the system.
In its current form, the retinal implants contain 10,500 electrodes. Each one generates a speckle of light.
"We weren't sure if this would be too many electrodes or not enough,” Ghezzi said. “We had to find just the right number so that the reproduced image doesn't become too hard to make out.”
That means the dots had to be far enough apart that a patient could distinguish between two of them, located close together. But there also have to be enough tiny dots to create an image that has good enough resolution to let the wearer identify patterns.
The researchers also had to make sure that two electrodes did not stimulate the same part of the retina. They conducted electrophysiological tests in mice, recording the activity or retinal ganglion cells, and confirmed that each electrode is activating a different part of the retina.
It turned out that using a number of light dots just over the 10,000 mark was the sweet spot.
"Our simulations showed that the chosen number of dots, and therefore of electrodes, works well,” Ghezzi said. “Using any more wouldn't deliver any real benefits to patients in terms of definition."
As for the field of vision, Ghezzi’s team tested out different angles, starting at 5 degrees and opening as wide as 45 degrees.
“We found that the saturation point is 35 degrees,” Ghezzi said, noting that “the object remains stable beyond that point."
Having shown the right parameters for making their technology a possibility, the next step is for Ghezzi and colleagues to get approval for clinical trials in humans. That could take some time, but the new research highlights a promising step toward delivering improved vision to people who otherwise don’t have the ability to see.
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