How is eye often shed tear to return a responsibility

Old tears may be related to cold wind stimulation, dust entering the eyes, etc., and may also be related to corneal diseases, such as keratitis, conjunctival stones, etc., eyelid entropion, ectropion and other eyelid abnormalities may also lead to old tears, and may also be related to lacrimal duct stenosis, dacryocystitis and other lacrimal duct system diseases.