I wear either glasses or contacts as well
as a HJC full face flip helmet.
You will discover if you choose contacts that
one of the benefits is, they don't fog up like
glasses do.
I would suggest investing in a 2nd pair of glasses
just to be on the safe side.
The glasses help filter out substances that can
get in your eyes even with a ff helmet, where
the contacts don't.
I have been riding 7 years and so far have never
had glasses fly off my face.
That again is possibly due to the ff helmet.
Best of luck on your decision.
kim & Genie