Eyes should be clear and bright. If Bucks get runny eyes, then wash out the eye in case it has something in it. Check the teeth as teeth problems can cause runny eyes. Check when you last administered Ivomectin (for mite control) if longer than two months it could be the cause. Clip the back of the neck and drop some on. If problem is consistent visit your vet, who can check for blocked tear ducts or back teeth problems.