It took 20 years and $200 million in funding, but the FDA finally approved Swiss company Second Sight’s Argus II retinal prosthesis last week after the Opthalmic Device Panel unanimously voted in favor of approval last September. The system restores partial vision to sufferers of retinitis pigmentosa, an inherited disorder that progressively destroys the light-sensitive rods and cones that make up the retina and affects 4,000 people in the U.S. and more than 1.5 million worldwide.
Argus II works by processing the video signal from a camera mounted on a pair of glasses into signals transmitted to an array of electrodes implanted in the eye and on top of the retina. These signals electrically stimulate the remaining retinal cells, and that electrical stimulation appears as an image to the wearer. The electrode array is only 60 pixels in size, so it doesn’t restore full sight but it does let the patient better distinguish static and moving objects, which is obviously a huge improvement over total blindness.
The device has already been approved for two years in the European Union, with some 30 people involved in an extensive clinical trial since 2007.
There are other companies and researchers working in this area, including teams at Stanford and Cornell Universities. A German company called Retinal AG has developed a much larger array of 1,500 photodiodes, amplifiers, and electrodes. Retinal AG has had its device implanted in 36 patients over the last six years, but unlike the Second Sight system, the array is implanted underneath the retina and should allow the recipient to drive, watch TV, and read books and newspapers. In short, people can have an almost functional restoration of vision.
Advances in photodiode technology, and miniaturization and speed improvements in digital signal processors, could see future devices matching or even exceeding human retinal resolutions, giving the blind a chance at a true “beyond retina” display.
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