Under normal circumstances the eye is kept moist by tears produced by glands on its surface. When something irritates the eye, or when we are affected by certain emotions, then the lacrimal gland releases a burst of water and we cry.
Where do tears go?
Along each eyelid, near the nose, there is a tiny hole (punctum) – the punctum is the entry point to the tear drainage system. The punctum is connected to a tiny tube that runs within the eyelid to the nose (canaliculus). Each canaliculus connects at the side of the nose to the lacrimal sac, the spongy structure at the “corner” of the eye by the nose. The lacrimal sac leads to the tear duct, which runs within the nose bones and empties into the nose. This connection between the eyelid and the nose is basis for a “runny nose” and for getting “choked up” when crying.
What causes a blocked tear duct in children?
During fetal development, the tear duct begins a solid band of cells within the nasal bones; normally these tear duct cells differentiate to form a hollow tube forms within the bone – the nasolacrimal duct. Sometimes, this duct is not completely open at birth – most often, this is because of a thin membrane running across the duct that prevents the tears from freely flowing (imagine a drumhead). Less often, the bone surrounding the duct is “tight,” pinching off the flow of tears. Approximately 5% of newborns have a NLDO; most often this is due to a membrane problem.
In NLDO the tear duct does not empty out into the nose, so the tears back up and overflow (epiphora). And because the tears don’t flow, the bacteria and mucous which are normally washed away can not be washed away. As you might imagine, stagnant tears sitting in a warm, dark tear duct makes a perfect home for bacteria to proliferate (build up) – these proliferating bacteria, and the body’s defensive immune response to them, produces a yellow-white discharge. Fortunately, this discharge very rarely means that there is a true infection – most of the time, it simply represents an overgrowth of bacteria (with infection, bacteria actually invade healthy tissue). This discharge poses no threat to visual development or to the eye tissues although it can be irritating to the skin and is not very attractive.
What to do?
Of the 5% of newborns born with a NLDO, 90% get better on their own by the age of 12 months– the membrane occluding the duct opens spontaneously. (In other words, out of 1,000 babies born, 50 have NLDO; by age 12 months, just 5 of these 50 still have a NLDO). Therefore, the odds are heavily in favor of spontaneous resolution. If the obstruction is caused by the nose bones pinching off the duct, this is less likely to spontaneously resolve.
Until an NLDO spontaneously resolves, there are measures you can take to minimize the build-up of the “gooey” discharge. First and foremost, gentle massage of the lacrimal sac should be performed (Crigler massage). This creates a vacuum, pulling out the bacteria and debris that have built up. The massage is performed by gently pressing, then releasing, the nasolacrimal sac itself; when done properly, you will feel a round spongy structure give a little and your baby will not feel any pain (try it on yourself). Performing this maneuver 5 to 10 times before each diaper change will typically keep the symptoms under control.
When massage alone is insufficient to control the discharge, then (and only then) antibiotics can be used. As you may know, the inappropriate and indiscriminant use of antibiotics has led to the development of bacteria that can no longer be easily killed by antibiotics – these drug resistant bacteria pose a threat to everyone,and it is everyone’s responsibility to use antibiotics responsibly. If you need to use antibiotic eye drops, then please take care to use them as directed; in this case, one drop 2 times a day to the affected side for 3 days, then try to go back to massage alone.
A final option is to open the membrane by placing a metal probe into the nasolacrimal duct to open any membranes and to feel whether or not the bones around the tube are tight. This can be done safely in the office if the baby is small enough to be held relatively still; the ideal age is 5 to 9 months. This procedure is reserved for those babies who have an obvious discharge or overflow tearing. The benefits of an in-office NLDO probe include an excellent chance of immediate cure and the avoidance of a possible general anesthesia (see below: “What if the NLDO doesn’t go away on it’s own by the first birthday?”). Other benefits include money and time saved (fewer eye drops, less time massaging, and no need to take off from work for a trip to the operating room). The alternative is to wait until 12 months of age, but… if there is no resolution by that age, then a trip to the operating room is indicated (see below). The risks of in-office probing include a failure to achieve cure, infection, nosebleed, discomfort, and damage to the nasolacrimal drainage system – these same risks apply when the procedure is performed in an operating room. If, at the time of in-office probing, it becomes unsafe to proceed (baby moves too much, etc.), then the procedure is immediately stopped. Probing the nasolacrimal duct on a person who is awake is not painful, but it is by no means a pleasurable sensation – this is often done for diagnostic purposes on adults who develop a NLDO.
How is a nasolacrimal duct probed?
This drawing demonstrates how the nasolacrimal duct is probed. First, the probe (a wire with a rounded tip) is placed into the canaliculus (see first diagram). Then, the probe is directed down into the duct. As you can see here, the probe exits underneath one of the nose bones – this diagram has a mirror (to your right) to demonstrate how it looks from inside of the nose.
You can also appreciate that the nasolacrimal duct exits underneath one of the nose bones. If this bone is pressing up against the duct, then tears cannot flow – this is why it is sometimes necessary to fracture the bone out of the way (not remove it). When the bone is fractured, it does not alter the appearance of the nose in any way.
What if the NLDO doesn’t go away on it’s own by my baby’s first birthday?
If an NLDO persists beyond the 11th month of age, then the baby would probably benefit from a probing of the duct with the need for any other surgical procedures determined by the probing itself – depending on how easily the probe goes in, and at whether or not the obstruction is caused by “tight bones.” The cure rate from a “simple” probing of the duct at 12 months of age is about 90%; this cure rate drops to 75% with probing performed at 13 months of age. One possible reason for this significant decrease in the success rate is that babies who do not get better on their own by 13 months are more likely to have more than a simple membrane blocking the duct– the bone around the duct is often tight and squeezing the duct shut, the nasal tissues are obstructing the duct, or there are other anatomic variations at play. It is impossible to tell what is causing the obstruction just by looking at the patient – the surgeon has to literally feel what the probe is doing and interpret what is causing the obstruction from this.
In addition to probing, a silicone tube is placed when there is a significant likelihood of duct closure occurring again; this is a tried and true method and has been around for several decades. The tube stays in place for up to 12 months and is not irritating; we can almost always remove it in the office. With the tube, you will see a tiny strand of plastic between the punctum of each lid; the patient feels nothing and the silicone tube is completely external to the eye – it is in the eyelid and tear duct.
If a baby needs NLDO surgery at the age of 12 months, she is too big to safely restrain in the office and a trip to the operating room is necessary (also, it is more likely that a silicone tube will be needed and this can not be done in the office). The risk of general anesthesia is minimal for a healthy baby and the risks of the surgery includes failure to achieve cure, infection, nosebleed, discomfort, and damage to the nasolacrimal drainage system; the vast majority of the time there are no complications.
Depending on the individual, it may be necessary to use a silicone tube to keep the duct open up to 12 months. This allows the duct to stay open while the tissues around it heal.
The silicone tube is attached to thin metal wires with a small ball at the end of the wires – the wire is placed into the duct and then retrieved from the nose with a special hook. Once in place, the tube is completely outside of the eye – it is in the eyelid and the nasolacrimal duct. If you looked at the corner of the eye next to the nose, you would see a piece of clear narrow, rounded plastic. Ideally, the tube stays in place for 3 to 6 months – sometimes, little baby fingers are able to pull it out. If this happens, then do not panic – there is no danger to the eye! If this occurs during office hours, then just come in and the doctor will remove the tube. If this occurs after hours, just tape the tube to the side of the nose and come to the office