I'm sorry you are having problems with your Kitten! It is scary when things happen to your pets because they can't speak and tell you what is wrong.
I know it can be expensive, but I would recommend taking your kitten to the vet. It is probably nothing, but it is better to be safe than sorry. I have a dog who is constantly having problems. I usually end up taking him to the vet like once every two months!
A kitten's eye which is dark red is most probably the result of conjunctivitis. Conjunctivitis is an inflammation of the lining membrane that covers the inner sides of the eyelids, and surface of the eyeball up to the cornea. It is one of the most common eye problems in cats and kittens. I would recommend the following hub which might help you understand conjunctivitis http://hubpages.com/hub/Cat-Eye-Problems
PS. You will still need to visit a vet, in order to confirm the ailment. Kittens are very fragile and need the correct type of care