When patients experience tearing, it could be due to excessive tear production by the tear gland or reduced drainage of tears through the tear duct system. It is important to differentiate between the two.
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 backflow of tears and discharge from the eye.
TEAR DUCT SYSTEM
This can be caused by foreign body entry into the eye, eye infection or inflammation, or malposition or laxity of the eyelid. Often, dry eyes can also cause tearing as a reflex response to the dryness.
This is the result of narrowing of the tear duct openings in the corners of the eyelids or of a portion of the tear drainage passages.
In children, the most common cause of a blocked tear duct is failure of a membrane at the lower end of the tear duct to open normally near the time of birth. However, in 90% of children, this obstruction resolves spontaneously in the first year of life.
In adults, it can be caused by ageing, sinus or nasal problems, tumours or facial trauma. Prior head and neck radiation treatment or chemotherapy are less common causes.
Besides tears welling up in the eye, overflow occurs onto the eyelashes, eyelids, and down the cheek.
The eyelids can become red, swollen and stuck together with yellowish-green discharge when normal eyelid bacteria are not properly flushed down the obstructed system. Severe cases may result in a serious infection of the tear duct system called dacryocystitis.
In children, a history of tearing and discharge from an early age is suggestive of a blocked tear duct. It is especially important in children that childhood glaucoma is excluded as it is an uncommon but important cause of tearing in infants.
Episodes of flu or nasal congestion may cause intermittent increased tearing.
In children, fortunately, tear duct obstruction resolves spontaneously in the majority of cases by age one. Tear duct massage, a short course of antibiotic eye drops may be recommended in the interim. If not resolved by age 12-18 months, tear duct probing with or without tear duct intubation on with a silicone tube has a high success rate of relieving the obstruction. Over 90% of children have symptom resolution after the procedure.
In adults, tear duct obstruction requires surgery to relieve the obstruction. This procedure in adults is called "dacryocystorhinostomy".
In children, a smooth probe is gently passed through the tear duct and into the lower opening in the nose. Using probes of progressively larger diameters can widen the tear duct.