Tears flow freely for most people, thanks to lacrimal and Meibomian glands. But tears are meant for more than emotion. They wash the eye, remove dust, and reduce risk of infection. A tear is a drop of mucous inside water coated with oil. DES prevents tears and causes burning, pain, sensations of in-eye grit, blurring, and eye fatigue. That would make many cry — but what if we couldn’t?