The main manifestation of congenital lacrimal obstruction is tearing in one or both eyes with increased secretion. A mass may be present in the lacrimal sac area. However, the diagnosis is not based on symptoms alone, especially in children who do not have a red or swollen mass in the lacrimal sac area, but also needs to be differentiated from other diseases with tearing symptoms. For example: impaired eyelid, congenital glaucoma, etc. A lacrimal duct irrigation test is an easy way to differentiate lacrimal obstruction from other diseases. During the test, a special flushing needle is used to inject flushing fluid into the lacrimal duct from the lower tear duct and observe the flow of the fluid. If there is no reflux and the child swallows, or there is fluid flowing out of the nostril, the tear duct is proved to be open; if the flushing fluid is completely returned from the tear point, the tear duct is proved to be not open. If the refluxed fluid is not clear, is cloudy, or has purulent mucus, this indicates significant lacrimal sac inflammation. Therefore, the tear duct irrigation examination is a means to understand the condition, confirm the diagnosis, identify the disease, and cleanse the tear sac and relieve inflammation. Some parents may have concerns about tear duct irrigation, but this is not necessary.