I had this weird experience once after eating "truffels" (underground mushrooms) who's precise name i forgot.
Normally i wear glasses or contacts but after eating the stuff the glasses were making me sick and when i put them off, my vision was perfect!
(i have -3.5 both sides)
I was with some friends and they didnt believe me but then they tested it (what's the number of that licence plate?) and saw i wasnt kidding...
The effect lasted for about 2,5hours. Then i started to giggle like a little girl for an hour
pretta weerd huh?