A 'visual prosthesis' implanted directly into the brain has allowed a blind woman to perceive two-dimensional shapes and letters for the first time in 16 years. The US researchers behind this phenomenal advance in optical prostheses have recently published the results of their experiments, presenting findings that could help revolutionize the way we help those without sight see again. At age 42, Berna Gomez developed toxic optic neuropathy, a deleterious medical condition that rapidly destroyed the optic nerves connecting her eyes to her brain. In just a few days, the faces of Gomez' two children and her husband had faded into darkness, and her career as a science teacher had come to an unexpected end. Then, in 2018, at age 57, Gomez made a brave decision. She volunteered to be the very first person to have a tiny electrode with a hundred microneedles implanted into the visual region of her brain. The prototype would be no larger than a penny, roughly 4 mm by 4 mm, and it would be taken out again after six months. Unlike retinal implants, which are being explored as means of artificially using light to stimulate the nerves leaving the retina, this particular device, known as the Moran|Cortivis Prosthesis, bypasses the eye and optic nerve completely and goes straight to the source of visual perception. After undergoing neurosurgery to implant the device in Spain, Gomez spent the next six months going into the lab every day for four hours to undergo tests and training with the new prosthesis. The first two months were largely spent getting Gomez to differentiate between the spontaneous pinpricks of light she still occasionally sees in her mind, and the spots of light that were induced by direct stimulation of her prosthesis. Once she could do this, researchers could start presenting her with actual visual challenges. When an electrode in her prosthesis was stimulated, Gomez reported 'seeing' a prick of light, known as a phosphene. Depending on the strength of the stimulation, the spot of light could be brighter or more faded, a white color or more of a sepia tone. When more than two electrodes were simultaneously stimulated, Gomez found it easier to perceive the spots of light. Some stimulation patterns looked like closely spaced dots, while others were more like horizontal lines. "I can see something!" Gomez exclaimed upon glimpsing a white line in her brain in 2018. Vertical lines were the hardest for researchers to induce, but by the end of training Gomez was able to correctly discriminate between horizontal and vertical patterns with an accuracy of 100 percent. Source
