My sister has stribismus and now wears contacts instead of glasses. her eyes keep crossing though which she claims is due to dry eyes messing up contacts.does she need new perscrip/go back 2 glasses?

Maybe: She should see a good md ophthamologist for an assessment. Is she is still young she might be a candidate for strabismus surgery to improve her "cross-eyed"mproblem and improve her stereoscopic vision.".

Strabismus: If someone has strabismus without glasses but not with glasses, it is possible that glasses may have corrective prismatic lenses in them. That may be the reason that your sister has strabismus with the contact lenses but not with glasses. Dry eyes may give double vision due to one eye being more dry and blurred vision as compared with the other eye which may be seeing more clear. Should see an md.

See your Eye MD: There is not enough good information to make a diagnosis, i would return to the eye md who is treating your adult strabismus.