There was a show a while back called the Invisible Man
It was pretty crap but it did have one interesting explanation for this. It said he wasn't invisible to infra-red and ultraviolet, so he could see in those spectrums just fine.
(
Spunk Murphy Tchaikovsky is a synonym for fanny, apparently,
Fri 11 May 2007, 22:06,
archived)
this would work too
c.f that thing they made invisible to microwaves, still could see it with the visible range
(
wjh31,
Fri 11 May 2007, 22:07,
archived)
ahhh, now that's a point
*ponders*
thank you!
(
Seventh is somewhat subdued,
Fri 11 May 2007, 22:09,
archived)