Actually, it is very possible for the eyeball itself to be damaged without it being visible to the naked eye. This is why one of the very first things a vet does when examining an eye is to put a flourescent stain into the eye to make any defects in the cornea more visible. Anytime there is a wound right next to an eye, a vet exam is warranted because damage to the eye heals slowly and turns very very bad very quickly.
Also, don't use Furacin (the yellow goop) near an eye. If you are going to use anything near an eye use a plain triple antibiotic ointment.
Licensed Veterinary Technician