My cats eye is swollen?

It sounds like he might have gotten an irritant in is eye. If he was laying on the floor(I'm assuming this is inside) he could have gotten carpet fibres, dust, even small crumbs in his eye that could cause a reaction. most people don't realise dogs and cats have eyes pretty similar in composition to our own. with an irritant, he could have scratched his cornea (minor abrasion) or he could have an eye infection. Monitor him and see if any other symptoms develop. If all else, take him to a veterinarian or call an emergency and ask.

Something is irritating your cats eye. The best thing you can do is get him to a vet. With the cat scratching/pawing at his eye, he could scratch the cornea.

If you can, apply a cold compress on his closed eye to reduce the swelling until you can get him to a vet.

Take a cloth & run it under some warm-hot water and gently press it on his eye. Sometimes this happens to my cats & if I do this a few times it usually goes away