I fly with prescription sunglasses. I am mildy short sighted so the type of frames that I could choose from was pretty vast as the lenses are as thin as non prescription sunnies. I normally fly with a pair of prescription Ray Bans, which have a brown lens in. I have found brown to be a good option as they arn't ridiculously dark. I haven't had any problems adapting from outside to inside the cockpit with them.
S