You're wearing the wrong kind of glasses. Whoever fit you did not take into account how important your vision is when you're performing. Are you wearing bifocals? If so, they should be progressive lenses... preferably a high quality progressive lens, such as one made by Varilux.
Also, the frame should be large enough to provide an adequate vision range, both horizontally and vertically.
With or without a headset mic, you should be able to see your keyboard, music, and audience easily and clearly.
Glenn