You try to have the budget for both normal glasses that have an anti-reflection coating, and special glasses with "flat" lenses. In general, for "Akeelah" we used the normal glasses with coatings, which wasn't much more curved than the flat lenses we carried as well (since our main character wore glasses, it was worth spending the money on multiple pairs and types of glasses).
Flat lenses only reflect in one direction, so either you can get no bad reflections or a really big reflection (sometimes you want that, like to reflect a computer screen in the glasses.)
But most of the time, we used the normal lenses with the anti-reflection coating, and I just tried to find an angle for the light that minimized the reflection, usually by raising it a little higher than the eyeline and/or tipping the glasses down. Some mild reflections are fine and realistic. The coating helps a lot too; without the coating, you get a really sharp reflection of light sources in the curved surface.
