Doc says i have allergy and dry eye. constant blurry vision and ghosting. vision does not improve with drops. with glasses still 20/20 .whats wrong?

See eye doctor: Allergic eyes only affect vision occasionally but dry eyes often do. Perhaps your vision is blurred because you need something more than just artificial tear but then I don't understand how you could have 20/20 vision if the vision were indeed blurred until this degree of visual acuity is only present intermittently. Please clarify.