Retinal implants for artificial vision

Diego Ghezzi, who holds the Medtronic Chair in Neuroengineering (LNE) at EPFL's School of Engineering and his team have been developing a retinal implant that works with camera-equipped smart glasses and a microcomputer. “Our system is designed to give blind people a form of artificial vision by using electrodes to stimulate their retinal cells,” says Ghezzi. The camera embedded in the smart glasses captures images in the wearer’s field of vision, and sends the data to a microcomputer placed in one of the eyeglasses’ end-pieces. The microcomputer turns the data into light signals which are transmitted to electrodes in the retinal implant. The electrodes then stimulate the retina in such a way that the wearer sees a simplified, black-and-white version of the image. This simplified version is made up of dots of light that appear when the retinal cells are stimulated. However, wearers must learn to interpret the many dots of light in order to make out shapes and objects. “It’s like when you look at stars in the night sky – you can learn to recognize specific constellations. Blind patients would see something similar with our system,” says Ghezzi. “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,” says Ghezzi. More specifically, the engineers developed a virtual reality program that can simulate what patients would see with the implants. Their findings have been published in Communication Materials. 

The retinal implants they developed contain 10,500 electrodes, with each one serving to generate a dot of light. 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,” says Ghezzi. The engineers also had to make sure that each electrode could reliably produce a dot of light. The next step was to check whether 10,500 light dots provide good enough resolution – and that’s where the virtual reality program came in. The engineers also performed tests at constant resolution but different field-of-vision angles. All these experiments demonstrated that the system’s capacity doesn’t need to be improved any further, and that it’s ready for clinical trials.

Source: EPFL news release