A tear duct has two small drainage holes in the inner corner of the eye called puncta, which connect to two thin channels, the canaliculi, which lead to the longer but wider lacrimal sac that runs along the side of the nose. That sac narrows, becoming the lacrimal duct.
The only parts of the tear duct that can be seen from the outside are the puncta, but only if the inner corner of the eye is pulled down to reveal the tiny holes. The only other visual indication is a small, soft bump in the corner of the eye next to the bridge of the nose. When a tear duct becomes infected or blocked, that bump is usually more pronounced.
Tear fluid is continually produced by the tear glands, located above the outer corner of each eyeball. Healthy tear ducts wick the moisture away and drain it through the nasal cavity. Normally this process goes unnoticed. When a person cries the tear glands produce more moisture than the tear ducts can handle and the fluid falls as tears.
Infections also interfere with this process. Since the tear ducts cannot properly drain the fluid due to swelling or blockage, excess tears are created. Doctors often press against the sinus area to diagnose a tear duct infection. If there is a problem, then a discharge normally appears.