Do glasses cause eye strain?

Maybe: If they are the incorrect power (most often too much nearsighted correction) they can cause eyestrain. Also, the lenses may be slightly misaligned from bent frames. Have them checked out by your ophthalmologist.

Yes: The wrong prescription in one or both eyes, poorly made glasses, interpupillary diameter distance problem, bifocal issue, prismatic effect from a bifocal, even the fit around the ear and nosepad problems may cause the feeling of eye discomfort. Have them checked out first to see if they are made correctly, then if they are the wrong prescription.