My cat had 2 kittens 14 days ago, and one of them still has an eye that remains closed. There seems to be some sticky stuff on the outside. Is this normal? Can I treat her at home, or do I have to take her to a vet?
You can start treating it at home, if it doesn't clear up in a couple days, then take her in (but it will probably clear up)
Brew some weak tea and let it cool, then dip a soft cloth in it and wipe the outside of the eye, you can also use a dropper and just drip a couple drips onto the eye.
Really though, mama will probably take care of it soon enough.