Fortunately, we don't have this problem...I guess we are lucky. I will add this though...something to think about. I was previously an Opthalmic Tech and as far as for HUMANS (again, not sure about with dogs) Visine is the worst thing you could possibly put in your eye...any form of Visine. It has small abrasives that can lead to corneal scarring. Again...might be something you want to check into? Just a thought...