The Blind Climber Who "Sees" with His Tongue
From: Discover Magazine - 07/2008
By: Buddy Levy

Erik Weihenmayer's BrainPort translates images into electrical signals. 

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. 

Read the entire article at:
http://discovermagazine.com/2008/jul/23-the-blind-climber-who-sees-through-his-tongue

Links:
BrainPort Balance Device
http://www.wicab.us/research/vision/vision.html

The Brain: "I See," Said the Blind Man with an Artificial Retina
http://discovermagazine.com/2011/sep/17-brain-see-said-blind-man-artifical-retina

Argus II Retinal Prosthesis Gets European Clearance
http://medgadget.com/2011/03/argus_ii_retinal_prosthesis_gets_european_clearance.html