Nasolacrimal Duct Obstruction
Tears normally drain through small openings in the corners of the upper and lower eyelids called puncta and enter the nose through the nasolacrimal duct.
Tear duct obstruction prevents tears from draining through this system normally. If the tear duct is blocked, there will be a backflow of tears and discharge from the eye.
The most common cause is the failure of a membrane at the end of the tear duct to open normally at or near the time of birth, but other causes of blocked tear ducts in children include:
- Nasal bone that blocks the tear duct entering the nose
- Absent puncta (upper and/or lower eyelids)
- Narrow tear duct system