Sprayed cat, something in eye

I accidentally sprayed my cat in the fact as I was trying to prevent him from running outside, he is an indoor cat. He has been sprayed before only very rarely and if it ever got near his eyes he'd just bounce back no problem, but this time he is squinting out of his left eye and I'm not sure (this is a new spray bottle) if something got in his eye? I tried to wipe it with a wet cotton ball, but it didn't really do anything. I opened his eye and for a second I thought there was a hair, but I don't want to check again since I don't want to irritate his eye further.
I'm assuming I just irritated his eye a little and it will go away, but at what point should I take him to the vet if it happens to get worse? It was a complete accident and I feel so bad for him now he opens it wide when I call him or something gets his attention, but if he's just sitting there he randomly closes it. This only happened after I sprayed him he was fine beforehand. The bottle did contain alcohol, but it was thoroughly washed and I sprayed it on myself as well and there isn't a hint of any of it and if there was, I'd think both of his eyes would be irritated. It was just an old bottle that was empty but held it before.

It's natural to feel bad about it but try to put the guilt aside. You most definitely had his best interest at heart, so don't beat yourself over this.

I agree that had it been some residue in the water both eyes would be affected. It maybe that the spray hit the eye to strongly. I would give it 24 hours and if there's no improvement, call the vet. 

Beyond the eye issue, it's generally not a good idea to spray cats as a disciplinary tool. It's a form of punishment (even if you don't mean it that way) and some cats can become overstressed and even learn to associate the owner with the negative experience. 

Here's an article with some ideas for different ways of teaching cats how to behave - 
[article="32493"]The Dos And Donts Of Cat Behavior Modification  [/article]