I failed the eye test at my school which was pretty hilarious. I was on like the middle sized line, and I said "R upside-down 4..." I think it was because the machine was so damn old and blurry itself. I didn't do great at the eye doctor place the first time either, because they bounced the letters off of two mirrors before you saw them. When I was tested on an LCD monitor the same distance away and the same size, I read it fine.
I got glasses after the first eye doctor appointment (and never wore them) but according to the second time, I don't actually need them.