Fever Hallucinations: a survey

I had the most amazing conversation. I was talking to this dude I know at a dinner party and he was like, "do you ever see some weird little object when you close your eyes that starts out really small and then gets really big and then small again? It happens when I'm sick. The background always looks like this one Photoshop effect."

I said, "yeah, I hate that." He thought I meant the Photoshop effect but I meant that particular vision when you're sick. I've seen little objects that expand and shrink behind my eyes every time I've been sick since I was little: spiky balls, Russian nesting dolls, you name it. But, as it turns out, so had everyone else at the table and none of us ever imagined that it was something that happened to nearly everyone. Most of us probably never mentioned it to anyone or thought about it much. It doesn't really affect anyone's daily life.

The guy who brought it up seemed to think it was kind of a cool experience to see these expanding, shrinking things. It usually just makes me even more queasy than I already am.

So does this happen to everyone? Why would so many people have such a similar experience when they come down with something? Do you know what I'm talking about? Someone get Oliver Sacks on the horn.