Dacryocystitis is a purulent or mucopurulent inflammation of the mucosa of the lacrimal sac caused by bacterial infection. There are two types of dacryocystitis: acute dacryocystitis and chronic dacryocystitis. In acute dacryocystitis, the main manifestation is the obvious redness, swelling, heat and pain in the lacrimal sac area, and most patients are likely to recover quickly if they are treated with antibiotics at an early stage. However, if treatment is not timely, an abscess may develop and surgical incision will be required to drain the pus. By the time the inflammation has completely subsided, most patients will still require surgery. Chronic dacryocystitis, which has a relatively long history of onset but no obvious symptoms of pain, is mainly characterized by lacrimation accompanied by purulent discharge. The common treatment is nasal lacrimal sac anastomosis. However, an imaging test is needed to assess the condition of the lacrimal sac before the procedure. Some patients with atrophy of the lacrimal sac can only undergo lacrimal sac removal, but the procedure will not improve the tearing symptoms. The recovery from lacrimal sac disease is inherently more difficult than for other inflammatory diseases, so early detection and active treatment is essential.