I promised my optometrist I would always wear glasses when I ride.
Going without glasses my contacts dry out badly which is uncomfortable as well as severely hampering my vision.
I have some extremely buggy areas to ride through along with the usual road splat and dust.
I do have trouble with the glasses fogging up on humid days and when I am very sweaty. Sorry doc, the glasses have to come off for a bit then.

I have 3 pair of glasses - clear, amber, and smoke. All $4 walmart safety glasses. Amber is good for headlight glare; clear is what I prefer for very dark rides in low traffic.