Tear duct irrigation is a way to check for blockage and narrowing of the tear duct as well as to treat mild tear duct blockage. Common diseases that may cause tear duct narrowing or opacification are mainly developmental abnormalities, or due to inflammatory infections. The main symptom is an abnormal “tearing” phenomenon, medically known as “tear overflow”. Some patients with inflammatory infections may also have increased discharge from the eyes, such as purulent discharge. The main way to determine the presence of these conditions is a lacrimal flushing examination. The routine approach is to first order a surface anesthetic and have the patient close their eyes for 5 minutes. Then, the patient’s lacrimal puncta (located at the edge of the eyelid in the inner corner, one above and one below) are located and a special, bluntly curved needle for tear duct irrigation is probed into the lacrimal puncta and inserted down the lacrimal duct, and no resistance should be felt in the process. A 5 ml syringe is used to draw saline, or antibiotic drops, into the lacrimal duct by way of injection. If the tear duct is completely open, the fluid will enter the throat without resistance and the patient will noticeably feel salty or bitter tasting water entering the throat. If there is resistance or reflux, it may be due to narrowing or obstruction of the lacrimal duct. This test also provides a general indication of where the lacrimal duct obstruction is located. Is it due to an abnormality in the lacrimal duct or in the nasolacrimal duct, etc.? In conclusion, lacrimal duct irrigation is a very important test in ophthalmology, relatively easy to perform, but very meaningful, mainly to determine whether the lacrimal duct is open or not.