How Do Tears Drain from the Eye?
Tears drain from the eyes through two small openings called the upper and lower punctum which are located along the upper and lower eyelids near the nose. They then flow through the canaliculus into the lacrimal sac located under the skin on the side of the nose.
From the sac, the tears are pumped by the blinking action of the lids into the tear duct. These ducts go through the side bones of the nose and empty the tears into the back of the nose. That's why your nose runs every time you cry.
What Causes Overflow Tearing?
Overflow tearing is usually caused by the presence of a persistent membrane that blocks the lower end of the tear duct inside the nose. Normally this membrane stretches or pops open at or before birth. In many infants however, it is still closed at birth clogging the tear drainage system. The blockage may open spontaneously in a few months as the infant grows.
Are There Other Causes of Overflow Tearing?
Very rarely, overflow tearing can be caused by congenital glaucoma. There are other signs and symptoms associated with this serious condition such as an enlarged eye, a clouded cornea, high pressure in the eye, light sensitivity, and infant irritability. Overflow tearing can also be caused by wind, pollen, smoke, or chemical eye irritation.
How Is Overflow Tearing Treated?
Initially, your doctor may recommend antibiotic eye drops or ointment used once or twice daily, along with pressure (or massage) over the tear sac. To apply pressure, place finger under the inner corner of the infant's eye next to the nose, and roll the finger over the bony ridge while pressing down and in against the bony side of the nose. This expresses mucus and tears from the sac. Following pressure on the sac, place an antibiotic in the eye. Most tear blockage in infants disappears by six months of age. If the tearing persists, it may be necessary for the ophthalmologist to open the tear ducts by probing and irrigation.
How Is Probing of the Tear Ducts Performed?
A thin, blunt metal wire is gently passed through the tear drainage system to open any obstruction. Fluid is then irrigated through the system into the nose to ensure that the pathway is open. Infants experience no pain after probing but some blood-staining of the tears or nasal secretion is common and a discharge from the eye may be present for up to a week. Antibiotics may be prescribed. Obstruction can recur and a repeated probing may be required.
If probings are not successful, plastic or silicone tubes can be placed in the drainage canals. This is a longer procedure than probing and requires general anesthesia. Occasionally, further surgery is needed to bypass the blocked tear duct and create a new opening through the bone into the nose.
What Complications Can Occur with Treatment?
As with any surgical procedure, there is the possibility of infection or bleeding. Scarring can re-obstruct the opening, requiring additional surgery. Chronic obstruction can lead to infections of the tear sac at any age.