Involuntary tearing of the eyes is a very common symptom in ophthalmology, mainly due to the following reasons. The first is caused by tear duct obstruction. When the tear duct is obstructed, the tears secreted by the eye cannot drain into the nasal cavity through the tear duct and will accumulate in the conjunctival sac, thus causing tearing. Secondly, it is caused by impaired eyelashes. When impaired eyelashes occur, the eyelashes will stick to the eyeball and scratch the cornea as the eye turns and blinks, causing reflexive tearing. Third, due to keratitis, inflammatory lesions on the cornea can cause irritative tearing. Fourth, due to the early symptoms of lacrimal gland infection, the early stage of lacrimal gland infection, inflammation stimulates the lacrimal gland in the secretion of excessive secretion of tears in the cells to form the performance of lacrimation. However, when the inflammation progresses to an advanced stage, the secretory cells in the lacrimal gland will suffer functional and structural damage, which will lead to a decrease in tears.