Do you mean polysporin eye drops? Go to your local pharmacy and ask the pharmacist for polysposin eye drops or polysopring eye ointments.... same thing but one is thicker.
The pharmacist likely keeps them behind the counter. No need for prescription; just they track the sale of it. Tell them it's for you and you are prone to pink eye so you always like to keep a fresh supply on hand. Something like that. They don't do veterinary....
Ointment vs drops:
If you get the eye ointment (ointment actually formulated for eyes). But a dab on your clean index and place that one to the eye and force the eyelids open and shut a couple of times to make it spreak.
Drops are easier just don't miss your shot.