The main causes of frequent tearing include the following: 1. Tearing caused by organic pathology of the tear duct, such as tear duct obstruction, tear duct stenosis, tear duct atresia, tear duct defect, lower tear duct ectasia, etc., which can be surgically corrected. 2. factors such as lid ectropion or conjunctival laxity, which lead to a decrease in the siphoning function of the tear duct, making it impossible for tears to be drained into the tear duct system in a timely manner, thus overflowing the eye surface and giving rise to symptoms of tearing. 3. 3. Receding eyelashes, which repeatedly irritate the surface of the eye, cause defects in the corneal epithelium and lead to lacrimation. 4. conjunctivitis or keratitis, which cause photophobia and lacrimation. 5. glaucoma, in which elevated eye pressure causes eye swelling, eye pain, eye redness and lacrimation.