The lacrimal apparatus is structurally divided into the tear-secreting and tear-discharging divisions. First, the lacrimal secretion department: including the lacrimal gland, the paracrine gland, and the conjunctival cupped cells. 1, the lacrimal gland is a reflex secretion lacrimal gland, in the external stimulation (such as corneal foreign body, chemical stimulation, etc.) or emotional excitement, its secretion of tears increased a lot, play the role of flushing and dilution of irritants. 2, paracrine lacrimal gland is the basic secretion gland, its secretion of tears is very small, is normal to reduce the friction between the eyelid and the eye, maintain the cornea, the basic secretion of the conjunctiva moist. 3. The conjunctival cupped cells secrete mucin, which helps to keep the eye surface lubricated. Second, the tear drainage department (tear duct): including the upper and lower tear dots, the upper and lower tear ducts, the common tear duct, the tear sac and the nasolacrimal duct. Under normal circumstances, in addition to the disappearance of tears through evaporation, part of the tears are discharged through the tear ducts. Third, the main symptoms and types of lacrimal apparatus disease: the main symptom is the flow of tears, the cause of two, one is the discharge is blocked, tears can not flow through the tear duct into the nasal cavity and overflow out of the eyelid called overflow tears; then is too much tear secretion, the discharge system is too late to drain away and out of the eyelid, called runny tears.