The common causes of tearing in the corner of the eye are divided into two cases, as follows: First, the tear secretion is normal, but the discharge system of tears has diseases, such as tear dots inversion, ectropion, membrane closure, or tear ducts because of inflammation, trauma, congenital malformation, blockage, narrowing, adhesion, tears can not be discharged normally from the tear ducts, overflowing outside the conjunctival sac, it will form corner tears. Second, the drainage system of tears is open, but the irritation of tear secretion increases and overflows outside the conjunctival sac. Clinically, the more common factors are dry eye, visual fatigue, impingement, foreign body into the eyes, conjunctival stones, allergy, inflammatory stimulation, etc.