I think when you just have that "out of the corner of your eye" thing it's normal eyes playing tricks. Even the cat running by. I have that one, too. I asked my psychologist about it quite a while back when I still had her, because it bothered me. Visual hallucinations are more full on, I guess. Like the 'man' figure I see is not out of the corner of my eye, he's always right in front of me. Sometimes just a shadow, sometimes in full color... scares the crap out of me.

But, you know, as always anything that is really bothering you should ask your doctor about.