I have never used safety glasses that go over prescription glasses.But I've heard that there are some safety glasses that can go over prescription glasses. As long as the safety glasses are designed to go over the prescription glasses, there may not be any problem with them. And you won't get any discomfort if you get them fitted your prescription glasses. I suggest you get a pair of prescription safety glasses if you need to wear prescription glasses.
Yes, someone has used safety glasses over the prescription glasses. It is said that four out of five outdoor activists suffer poor eyesight and they want a pair of glasses that can both help them see clearly and protect their eyes when they do outdoor exercises. For those people, safety glasses become a necessity, and they begin to wear prescription glasses and safety glasses at the same for eye protection and vision aids.