I have always thought the eyeball thing would be a good way to protect yourself from a person who grabs you by surprise. When I walk across a parking lot to my car, I have my keys in my hand with poking a key into the eyeball of an attacker in mind. I am small and old and I might not be able to pull it off but I would try. Never thought of doing that to an animal.
If you shove a key into someone’s eye, all efforts to attack you will immediately cease. Do not aim for one eye, aim for the bridge of their nose. That way no matter which way they turn their head, you will be on target.