As far as I am aware, there aren't any prescription scopes. However, many people have said that with a good quality scope, it can more than compensate for poor eye sight especially at dusk and overcast days.
There are some scopes such as the Leupold VX and VXR that have normal crosshairs as well as the option to get a red dot with the press of a button. Something like that might work, if he does have trouble focusing on the reticle.
Really though, the only way to know is to get him to look through some scopes. Conditions similar to how it will be used is best, same with buying TVs. What seems great in a well-lit store against the background of a white wall may not even be usable in the forest on an overcast day.
I'm nearsighted, and I always shoot with my glasses on anyways, but sometimes it's a royal pain to have to keep moving the glasses further away from my face so they don't fog up but without going so far they fall off my nose and I can't see anything.