A blocked tear duct is an obstruction or complete scarring of the nasolacrimal duct in the nose. This duct is more commonly known as the tear duct.

What is going on in the body?

Tears are produced by a gland under the upper eyelid. The tears are constantly released onto the eye's surface in small amounts. Blinking moves tears toward the inside corner of the eye. There the tears drain through small canals into the nasolacrimal sac in the nose. From there, the tears go down the tear duct into the back of the nose and then down the throat. If there is a barrier anywhere along this route, it is called a blocked tear duct. This can happen on one or both sides of the nose.

What are the causes and risks of the condition?

Babies often have discharge and tearing of the eyes. This is because a membrane in the nose is blocked. Usually, it opens spontaneously at birth. Even if the membrane does not break during birth, the problem usually goes away after a few months. However, if the membrane does not open by itself in 6 to 9 months, the chance that it will self-correct is low. Treatment will be required.

Sometimes, a past nose injury or frequent sinus infections can cause scarring of the nasolacrimal duct. This can cause complete blockage of the duct.