D.B.
Sounds like it might be conjunctivitis which is treated with antibiotics. It comes from rubbing the eyes with germy hands, particularly if the person has a cold and transfers the germs to the eye. The junk gets crusty as it dries. You can soften it with a warm washcloth, but then you must put the cloth in the wash and then do a good job washing your own hands as it's very contagious..
It could also be a reaction to seasonal or animal allergies. In that case, no antibiotics will work but the warm compresses will.