I don't use glasses, but I believe that glasses won't help wearing under the helmet...they're gonna be a hassle under the helmet, when you take off your helmet or when you put it on.
Regardless, it will be even more difficult trying to look thru the visor, based on the fact that you have limited visibitily (or points of view in this case) if you use glasses, even though I have problems trying to look thru the visor, and I have to get really close to it to have a better field of view. And I'm not even talking about wearing the helmet while in low-light environments.
Robert