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Retinal Implants Can Give Artificial Vision to the Blind

AHA Publisher — Wed, 10 Mar 2021 08:00:35 +0000

École Polytechnique Fédérale de Lausanne (EPFL) via Newswise – Newswise — Being able to make blind people see again sounds like the stuff of miracles or even science fiction. And it has always been one of the biggest challenges for scientists. Diego Ghezzi, who holds the Medtronic Chair in Neuroengineering (LNE) at EPFL’s School of Engineering, has made this issue a research focus. Since 2015, he 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. Star-Spangled Sky 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. Running Simulations, For Now The only catch is that the system has not yet been tested on humans. The research team first needs to be certain of their results. “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 just been published in Communication Materials. Field of Vision and Resolution Two parameters are used to measure vision: field of vision and resolution. The engineers therefore used these same two parameters to evaluate their system. The retinal implants they developed contain 10,500 electrodes, with each one serving to generate a 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,” says Ghezzi. The engineers also had to make sure that each electrode could reliably produce a dot of light. Ghezzi explains: “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 step was to check whether 10,500 light dots provide good enough resolution – and that’s where the virtual reality program came 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,” says Ghezzi. The engineers also performed tests at constant resolution but different field-of-vision 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,” says Ghezzi. 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. But the team will have to wait a little longer before their technology can be implanted in actual patients. For now, restoring vision remains in the realm of science fiction. To read the original article click here.

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First In-Human Trial of Synthetic Cornea Starts in Israel

AHA Publisher — Fri, 24 Jul 2020 07:00:04 +0000

Israel21c Staff via Israel21c – The first-in-human implantation of the revolutionary CorNeat KPro synthetic cornea has been approved for 10 corneally blind patients at Beilinson Hospital in Petah Tikva. CorNeat KPro was developed by CorNeat Vision of Ra’anana. The implant is designed to replace deformed, scarred or opacified corneas and is expected to fully rehabilitate the vision of corneally blind patients immediately following implantation. The device’s lens, which provides optical quality equivalent to a perfect cornea, integrates with the patient’s ocular tissue using a unique patented nano-fabric skirt placed under the conjunctiva. “Following rigorous preclinical testing and successful animal trials, we feel confident moving on and proving our device’s safety and efficacy in humans,” said Dr. Gilad Litvin, CorNeat chief medical officer and the KPro’s inventor. “Our device’s implantation procedure, which has been developed and perfected in the past four years, does not rely on donor tissue, is relatively simple and takes less than an hour to perform. We expect it will enable millions of blind patients around the world, even in areas where there is no corneal practice nor culture of organ donation, to regain their sight.” The clinical trial at Beilinson will be led by Dr. Irit Bahar, chief of ophthalmology. Test patients will be people who are not candidates for, or have failed one or more corneal transplantations. “The technology behind this implant, which enables to permanently and bio-mechanically attach synthetic materials to live human tissue, is key in turning the tide on global corneal blindness,” said Bahar. Additional trial sites are planned to open later this year in eight hospitals in Canada, the United States, France, China and the Netherlands. “CorNeat Vision’s implant is poised to revolutionize corneal transplantation,” said Canadian ophthalmologist Dr. David Rootman. “This new solution is completely synthetic and does not rely on donor tissue, which can carry a virus or any other disease – a key differentiator during this COVID-19 crisis, which greatly impacted the availability of corneal tissue.” To read the original article click here. For more articles from Israel21c click here.

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Electrical Stimulation Could Restore Vision in Blind People

AHA Publisher — Fri, 10 Jul 2020 07:00:40 +0000

University of Zurich via News-Medical Net – In a project under Horizon 2020, researchers from seven European organizations will examine how the vision of visually impaired people can be restored using electrical stimulation of the brain. The project is being coordinated by the University of Zurich and supported by the European Union with funding of 4 million euros. If a project receives funding from the European Union, it must involve excellent science in innovative and promising interdisciplinary research fields that provide new and relevant ideas for industry and society. The international Neural Active Visual Prosthetics for Restoring Function project meets all these criteria and has been awarded an EU research grant totaling 4 million euros over four years. The project will kick off on 1 September 2020 and is being coordinated by Prof. Shih-Chii Liu at the Institute of Neuroinformatics of the University of Zurich. Working in interdisciplinary teams from seven European universities and institutions with complementary expertise in computational, systems and clinical neuroscience, materials engineering, microsystems design, and deep learning, the project will develop technology to restore the vision of blind people through electrical stimulation of the brain. Close Interdisciplinary Cooperation The aim of the project is to develop a neuroprosthesis with thousands of electrodes driven by adaptive machine learning algorithms for a new brain-computer interfacing technology. “We want to create a novel neuroprosthesis system that is lightweight, robust and portable, and which will remain effective for decades,” explains Shih-Chii Liu. Current systems only stimulate a small set of neurons in the brain, and interfaces have longevity of only a few months. Liu is convinced that the project will succeed in its goals: “All the partners have long-time experience in their respective fields, so the required background knowledge is already in place. The breakthroughs will come with the planned larger-scale efforts and partner interactions in this project.” The challenge will be coordinating the expected breakthroughs across multiple disciplines. Establishing Innovation These breakthroughs include innovative approaches for stimulation with high-electrode-count interfacing with the visual cortex. For this, thin flexible probes are needed that cause minimal tissue damage as well as new electrode coatings and novel microchip methods. The researchers will also channel the stimulation currents to many thousands of electrodes and monitor neuronal activity in higher cortical areas. Breakthroughs are also expected when it comes to artificial neural networks trained by deep learning, which will only extract the most relevant visual information from a camera input to enable blind individuals to recognize objects and facial expressions and navigate through unfamiliar environments. These networks will transform the camera footage into stimulation patterns that drive the neurons in a way that the blind person can interpret. This is the only way that the signals can be processed and passed on. At the same time, eye tracking will be used to improve perception in a closed-loop approach. The Algorithm Translates Stimulation Patterns In addition to coordinating the project, the University of Zurich is also contributing to its technological expertise. The neuroinformatics team of Shih-Chii Liu and Tobi Delbruck will be working with consortium partners to develop power-efficient neuromorphic deep learning hardware and algorithms. The network implemented on the neuromorphic hardware will translate camera input into stimulation patterns to drive the stimulation electrodes. This research project is important because it lays ground-breaking work for constructing a new brain neuroprosthesis and brings added benefits to other neuroprosthesis research.” Shih-Chii Liu, Professor, Institute of Neuroinformatics, University of Zurich The involved researchers hope that the project will raise Europe’s still relatively low profile in this research field. To read the original article click here.

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