sometimes i have this weird thing, it starts with what looks like a blind spot in the center. I have trouble reading, if i look at a word i don't see first letter or couple of letters. Later on the blind spot moves to the left and gradually disapears. Acctualy i'm having one of those things right now. It doesn't happen often the last one was probably several months ago. It comes and goes away in 30 minutes or so. Oh and it seems to be mental thing 'cause it doesn't matter if i close one eye or the other blind spot stays in the same place. Except when blind spot moves to the left, right now i can see ok with my right eye and the left one has huge blind spot. Any idea what this might be?