My cat has a swallen and runny eye, what should I do?

Hi, Maria,
This usually, but not always, indicates an eye infection. Please take your cat to a Vet, get a professional opinion, and if it is an infection, the Vet will give you some medicated drops or jel to put in the eye.
I do wish you and your cat the very best.
Thank you for posting a question here; and hope you will come back.

There are many things that it could be, the first and utmost is rhinotracheitis virus and calicivirus which appears to be an eye infection, but this eye infection is indicative of a corresponding upper respiratory infection.

With you saying that it is swollen, rhinotracheitis virus and calicivirus does not seem likely. This infection is generally spread from cat to cat,

The other is conjunctivitis but this is a discharge. I am not a veterinarian but it is more than likely allergies or your cat may have run something in it, needless to say you should take your cat to the vet and have it checked out along with the things I have listed there are many more that it could be. If you would like to research this a little further please try Pet Education.com this is a great site when you need a correct answer for a pet question. I am not a vet, your best bet would be to see one ASAP. (O: