Recently it has come to my attention that my left pupil is larger than my right; this is usually a sign of neurological trauma, ranging from a random cutting off of the blood supply due to a particularly nasty migraine to other, rather rare and disturbing things, like cancerous tumors pressing against the ocular nerve. I'd actually been noticing it myself, but thought that perhaps I'd been imagining things, especially because it is mostly noticeable in lower light when the pupils are more dilated anyway, but I didn't believe it to be real until someone else said to me, "hey, did you know that one of your pupils is larger than the other?"
Conveniently, in my work at the writing center, I have a weekly appointment with a man who is a cancer research specialist at OHSU and I thought I'd ask him whether I should be worried. Many minutes later, after he'd run through the litany of potential causes and thoroughly panicking me, he told me to go find a photograph of my eyes to see whether I could pinpoint when this change occurred, or if I'd had one larger pupil my whole life (a rare, but possible genetic condition). If it were something that had changed recently, there was a reason, and I'd need to get it looked at immediately.
So, I found a picture of myself taken when I was eighteen and, as it turns out, the left pupil was larger than the right even way back then. No one had ever noticed. Not my mother, not my boyfriends/lovers, not even me. My OHSU friend had said to me "It isn't possible that no one has ever looked into your eyes closely until this time?" (he's German) but truly, I guess not. Not really anyway. How could I have missed it all this time? Oh well, it would seem that I am in no danger of needing brain surgery any time soon, so that's a plus.