I have the prescription Ray Bans, but before I got them I was wearing a pair of Serengeti's. From what I was told, you can't have lenses that are too curved to be prescriptions because they'll just warp everything you see. But also with Serengeti's you probably don't wanna take those lenses out. That's what makes the glasses so good. I've just gotten my Ray Bans tinted to a darker shade.
Hope that helps!