For those who are concerned ...
My friend is a retired Naturopathic Doctor who is homeschooling their youngest child. Unfortunately, there's no money for vets but Laura's awfully good at treating the family - even the 4-legged ones.
Curly is an outdoor/indoor cat. When he came in yesterday morning, he was staggering around & vomiting, which led Laura to believe he'd been poisoned. She treated him appropriately for that and kept giving him water to keep him hydrated. A few hours later, the vomiting had subsided but he started sneezing, his eyes became rheumy and his breathing became labored but his breathing finally normalized and he slept for awhile.
She woke him up yesterday evening to give him some more water & noticed that he appeared blind - he wasn't responding to visual stimuli. He did complain about his situation (a good sign) and staggered under the daughter's bed to sleep.
This morning, she thinks he can see shadows but in addition to affecting his eyesight, he apparently has some neurological damage to his legs - he takes "little old lady" steps and can't lift his legs high enough to get into the litter box.
All this is leading me to believe he hasn't been poisoned (at least in the conventional sense) but has been bitten by some spider - possibly a brown recluse, although Laura can find no bite site. He does, however, have thick fur which may be hiding it.
Curly is better but not out of the woods, yet. Any and all positive energy for Curly is much appreciated. He's only 8 and is a really sweet guy. (I told Laura I'd put the word out and she says to convey her thanks to everyone.)