here's a 'Wired' article from 2002
I don't know if Dobelle is doing this or not for Stevie Wonder..
It would be a problem for people blind from birth (re development of visual cortex) - I don't know whether the cortex atrophies from long lack of use, or if it could be 'restarted' after years .. anyway RL is right, the 'sight' is rudimentary, either with retinal chips implanted into existing eyes with destroyed retinas, or with Dobelle's methods of direct connections from a camera into the visual cortex.
I really do hope though that signficant improvements and cost reductions could come about in my lifetime ..