Chronic dacryocystitis is a common eye disease, except for the outflow of pus, the surface skin is not red, swollen or painful, so it is often neglected and treatment is delayed. In addition to tearing and pus flowing all day long, which brings great inconvenience and pain to daily life, chronic lacrimal sacitis can also cause acute and chronic keratitis, corneal ulcers; the eye cannot be operated on internally; tear outflow erodes the eyelid, making the eyelid skin dry, pigmented and ectropic. The pus that comes out of the lacrimal sac contains a lot of bacteria that can threaten the eye at any time, so some people refer to it as a “time bomb” next to the eye, and it should not be taken lightly. It has been suggested that the cause of chronic dacryocystitis is obstruction or narrowing of the nasolacrimal duct, which is commonly caused by inflammation of the external eye, such as trachoma, conjunctivitis, blepharitis, and dacryocystitis. In addition, there is also a relationship with the width and length of the nasolacrimal duct, or the deviated nasal septum, enlarged inferior turbinate, chronic rhinitis, and other factors. Chronic dacryocystitis should be treated with a lacrimal sac nasal mucosal anastomosis at the earliest possible time. The prevention of chronic dacryocystitis can start from the following aspects: 1. Keep your eyes clean and hygienic, without rubbing your eyes with dirty hands or dirty handkerchiefs. Actively treat trachoma, blepharitis, conjunctivitis and other external eye inflammation to prevent bacteria from taking advantage of it. 2. If you have tears in the wind, you should go to the hospital as soon as possible to find out the cause and treat it in time. 3. Those who have nasal diseases such as deviated nasal septum, enlarged inferior turbinates, chronic rhinitis or nasal polyps should be treated as early as possible.