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According to an article published on April 24, 2007, a group of American scientists has pioneered the development of a "bionic eye", using electrodes to stimulate an area of the brain that processes visual information.
The results obtained in monkeys, which were published in the journal Proceedings of the National Academy of Sciences, increase the chances that people with diseases such as glaucoma will one day regain their sight with a prosthetic eye.
However, experts warn that it would be very difficult to implant enough electrodes to create a complete picture in the mind.
For years, researchers have sought various ways to restore vision to people who have been blinded by an accident or by diseases such as macular degeneration. In these patients, the eye has stopped working, but the visual centers of the brain are intact. The goal, in these cases, is to ignore the eye and stimulate the visual parts of the brain to recreate an image in the mind.
The team used monkeys with normal vision to see if it was possible to produce a visual signal by stimulating an area of the thalamus. To do this, they first trained the monkeys to look at points of light that suddenly lit up, and then implanted one or two very thin electrodes in the appropriate area of their brain to see how they would react. In this way, they observed that the monkeys moved their gaze as when a point of light appeared.
According to the director of the research, Dr. John Pezaris of Harvard Medical School, this experiment is an important step, but the main difficulty for a prosthesis in humans is that many more electrodes would have to be implanted. "We would have to increase the number of electrodes 100 times so that it could be useful in patients."
In addition, he pointed out that the electrodes should work together so that patients could distinguish patterns and therefore complete images.
The idea is that one day a patient will wear a series of special lenses with a tiny digital camera. An external signal processor would translate the image from the camera into impulses and transmit them wirelessly to a stimulator implanted in the brain, which would create the images for the visual system.