Blind climber uses special equipment to see 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.”