TV, PS3, Idle time question

the wearable tv gadgets have been out for a long time, when I was stationed in japan in 2000 I had a friend who had a pair (not HD of course)
I did try his out once but personally I don't know if I could use them for an extended period of time, and I would always be worried about if it was affecting my vision. I'm sure they would say something like 'its set so that you are sitting at a distance of blah blah feet away from a normal television' but that wouldn't change my mind