That's fascinating. It makes sense, in an odd way. His eyes are still functioning, but the brain can't process the incoming data, so things get remapped to areas of the brain responsible for other types of functions.

I have a bit of the opposite problem. I have a mild form of Charles Bonnet syndrome. The visual hallucinations I experience aren't extremely frequent or complex. I may have one every few days to every few weeks, and they usually only last for a couple of seconds. Mostly I just see abstract shapes (usually the same shape - kind of a glowing horseshoe). Once or twice, I have seen chairs.

Here's a great TED talk on it: http://www.ted.com/talks/oliver_sacks_what_hallucination_rev...