This disease is called Dry Eye Syndrome or Sjogren's Syndrome . People who have diseases like rheumatoid arthritis or lupus often have this condition. They must use artificial tears up to every 10 to 15 minutes, and apply other medications to their eyes before going to bed as part of the treatment to improve the condition of their eyes. Think about the things you do and the places you go where your eyes need protection. If Dry Eye Syndrome goes untreated it can cause blindness.
Humans are the only animals that cry emotional tears.
This also affects saliva glands. Resources Frey, William H. and Lanseth, Muriel. Crying, the Mystery of Tears. Winston Press, 1985. The Anatomy Coloring Book.