Plastic or Glass Lenses?
Plastic...look at trying the "Meguires Plastic Polish"...the stuff you use on those yellowed/crazed plastic headlight covers...and a small buffing wheel on a Dremel tool...VERY LIGHTLY...
Otherwise...if it's glass, head over to the optometrist that did your set for you in the first place...they should have the gear in the back to "buff" that right out...
Mine were scratched a few years back and they took my glass glasses and had me back on the road in 15 minutes...no appointments or anything...and since I got the prescription filled there, N/C for the time.
I dropped off a box of
Krispy Kremes the next time I came through - I still get a smile from them when they see me in the lobby...