Lacrimal duct obstruction is a condition that often occurs at the lacrimal dots, lacrimal ducts, the junction of the lacrimal sac and nasolacrimal duct, and the inferior nasolacrimal duct, with tearing as the main symptom. Congenital Hasner valve obstruction is the most common, along with congenital lacrimal atresia (including bony atresia of the nasolacrimal duct due to bone malformation), congenital absence of the lacrimal dots, and deviated nasal septum. The pathway of tears under normal conditions: tears flow through the surface of the eye, then through two small openings on the inside of the eyelid, namely the tear dots, from the tear dots to the upper and lower tear ducts, and then from the upper and lower tear ducts to the tear sac, and finally down to the nasolacrimal duct, which then opens below the nasal cavity, through which the tears flow. If the lacrimal duct is narrowed and blocked, the tears will overflow to the cheek. The main symptom of lacrimal duct obstruction is tear flow and mucus-like discharge when infected. The nasolacrimal duct is the latest to form, often with a mucosal fold (Hasner flap) partially or completely covering the opening of the nasolacrimal duct at birth, and usually opens on its own within 4 to 6 weeks after birth. Incomplete development of the lower end of the nasolacrimal duct, incomplete “canalization”, or obstruction by membranous material, is the main cause of lacrimal overflow in infants. It can occur in one or both eyes, and if there is secondary infection of the lacrimal sac, mucopurulent discharge can occur, resulting in neonatal dacryocystitis. Tear duct flushing treatment and judgment of obstruction site: the method of judging the obstruction or narrowing site of the tear duct according to the fluid discharge. 1.The lacrimal duct is narrowed if only part of the fluid is injected from the lower tear duct into the nasopharynx and part of the fluid is refluxed from the upper tear duct. 2, all the rinse fluid from the upper tear point reflux for the common lacrimal duct lacrimal sac end obstruction or nasolacrimal duct obstruction, such as a large amount of mucus secretions flushed out for the nasolacrimal duct obstruction chronic dacryocystitis. 3, all the flushing fluid returned from the lower tear dots, flushing resistance, should then flush from the upper tear dots, if the tear duct is open, then the lower tear duct obstruction, such as the upper tear dots flushing also from the original upper tear dots reflux for the common lacrimal duct obstruction. Surgical treatment for lacrimal duct obstruction: lacrimal duct irrigation or lacrimal duct exploration within 1 year old, when 1 year old, the lacrimal duct obstruction cannot be cured by lacrimal duct irrigation or lacrimal duct exploration, only the lacrimal duct obstruction can be cured by surgery. 1.Probe and place the tube. Repeated probing and gradually increasing the size of the probe to enlarge the nasolacrimal duct can be used, which is effective for a few mild or fibrin adhesions obstruction, but it is difficult to work with fixed scar. After probing, a thread such as silk, intestinal thread, polyethylene or silicone tube is placed and left for 3-6 months to form a channel. 2.Obstruction incision. There are various methods of incision, such as special knife incision, electrocoagulation or electrolysis, retrograde incision of obstruction from above or inside the nose, etc. 3.Nasolacrimal duct prosthetic duct surgery. After exploring the enlarged nasolacrimal duct, a prosthetic tube with an inner diameter of 1.5~3mm is placed. 4.Lacrimal sac nasal anastomosis. The most ideal way to block the lacrimal sac is lacrimal sac nasal anastomosis. 5.Laser lacrimal ductoplasty. The laser is used to open the narrow obstruction of the lacrimal duct, common lacrimal duct or nasolacrimal duct, and combined with drug infusion, this surgical method can restore the physiological channel of the lacrimal duct.