The Blind Climber Who "Sees" With His Tongue
Published: Jul 3, 2008A wiry man in his late 30s hangs near the top of a 40-foot wall, the toes of his climbing shoes barely gripping the sheer face. He clings with his left hand and pauses, swinging his right arm to the side, loosening the muscles. Then he raises his head and lunges, thrusting his right hand above him and catching a rock hold with his fingertips. With a few more moves he arrives at the top. Under normal circumstances this extreme rock climber would be worth watching. But what makes his effort even more remarkable is that he happens to be blind. Born with retinoschisis, a rare disease akin to macular degeneration, Erik Weihenmayer was sightless by age 13. Even so, he continued to pursue his dream of mountaineering, and he succeeded: In 2001 he became the first—and to date the only—blind climber to summit Mount Everest. Today he is climbing with the aid of a tool that allows him to “see” in a new way—with his tongue.
In normal vision, light hitting the retina provokes electrical impulses that the brain translates into images. What the tool, called the BrainPort, does is convert light into electrical impulses that stimulate the tongue instead of the retina. With more tactile nerve endings than any other part of the body except the lips, the tongue can discriminate two points spaced less than a millimeter apart. That degree of resolution is far beyond what the current BrainPort array, with only 611 electrodes, provides. But tests have shown the BrainPort delivers enough information for users like Erik to navigate with.
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