Saturday, May 5, 2007

anisocoria (that's pronounced 'gawd, aren't i stupid?')

we had an emergency surgery come in yesterday at 4:15pm. sucks, eh? on a friday afternoon. i didn't leave school until 7pm (and i got there at 8am, of course). at any rate, it was a dog with an iris perforation (or prolapse). this occurs usually when the dog has a really bad ulcer that eats all the way down through the cornea. the iris muscle can then pop out of the ulcer and hang around. not good, obviously. we went to surgery immediately to fix it. after it was over, dr m asked me to place some atropine in the dog's eye. atropine is a mydriatic/parasympatholytic. see, your pupils are under sympathetic nervous system and parasympathetic nervous system control both. when your sympathetic nervous system (from now on SNS) kicks in you have a fight or flight response. your heart rate skyrockets, you start to breathe fast, your muscles get more blood flow, and your pupils maximally dilate to let in more light for better vision. when you're relaxed, your PNS is running, and your pupils are constricted and small. well, atropine is a parasympatho-lytic drug, which means that it 'lyses' the PNS response. one result of this is that your pupil dilates. anyway, i put drops in the dog's bad eye, and went about my business. when i came home, jim and i had dinner, watched a movie. then i went to take my contacts out and was given quite a start. my left pupil was huge. my right was small and normal. it took me a minute, but it occurred to me almost immediately that i must have inadvertently touched my own eye after giving the drops.

i feel stupid because they warned us that this might happen and to be careful. and yeah, i wasn't obviously. last year, a student did the same thing. only she didn't come to the realization of what must've happened. instead, she saw a doctor and went through a score of tests before - midway through the testing, she realized what had happened. she was so embarrassed that she let the doctors finish the tests rather than tell them.

oh yes, unequal pupil size is anisocoria.

so i promised to talk about the dog with diaphragmatic hernia. but i'll start another post because alison has complained that mine are currently too long.

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