Originally Posted by riccil0ve
I'm not underestimating the importance of having a vet out, but it's possible that he just got something in it, like dust. Or he could have just poked it. Did you wipe his eye off? Get a towel soaking wet with cold water and wipe his [closed] eye as often as you can. It has to be really wet so it can flush out his eye.
Warm cloth is better than a cold cloth on a swollen eye. Not as much of a shock to the system.
We also keep saline on hand to rinse the eye.