My bunny has gooey stuff in one eye?

Well, at first I thought it was just this whisker he had curling into his eye that was irritating it, so I took care of that but he still has some drainage in one eye? The other eye is fine, and his nose looks fine. He is just under 6 months old and I'm not feeding him anything he shouldn't be eating at this age, and he takes vitamins. What is this and what do I do about it?