Swollen eye

Muffin's right was swollen shut when I arrived home today. It was fine this morning, and the left eye is still fine.

I cleaned it with a wet towel and he is now opening it halfway, but still not all the way. It looks irritated and there is a thin white film extending from the inside of the eye toward the pupil.

Is this common in cats? What can it be?

She might have scratched it or rubbed it too much.  If it's still swollen in the morning, I'd get her to the vet to have her eye checked out.
 

Is this a good idea to use a damp cloth soaked in water and gently press on the eyes? one of my friend told so... is it safe?

You can use a warm damp cloth (cloth dampened with warm water and wrung out) to soothe the eye.  The lining you see is the third eyelid.  Usually anytime you see that, it indicates the cat isn't feeling well or there's something to watch regarding the eye.
 

Yes, that third eyelid must be what's covering part of his eye. He has some sort of discharge coming from the eye. I cleaned it with a towel and it seemed better, but then more appeared and the discharge appears to be what is causing his eye to stick shut. Going to call the vet tomorrow...

What you described, sounds like the 3rd eye lid. Anytime you see that, that means there is an infection somewhere, and the kitty needs to be seen by a vet. 

If the discharge is clear, that means its viral, airborn, and it has to run its course, they won't give you antibiotics, they won't work, but you can put terrymycin in the eye and give the kitty L-Lysine.

If the discharge is gunky, then there is an infection in the eye, and they will give you antibiotics, something to put in the eye and you should still put the kitty on L-Lysine.  

L-Lysine is an immune booster, some give it all the time, some give it when kitty is sick. The usual dosage is 250 mgs once a day, if kitty is 9 lbs or under. 250 mgs twice a day, if kitty is over 9 lbs. You can get it in the human vitamin section.  You cut the pills in half and smush them into a powder, and mix with a good amount of wet food, mix well, some don't like it. I use 1/2 3.0 can, and I add water, so its like a thick soup.  

Here is a good site to read about eye infections. Hope kitty is feeling better soon.     

http://www.peteducation.com/article.cfm?c=1+2124&aid=250