Tearing is a common problem our patients bring to us. When considered in the way a plumber would solve the problem, it becomes more straightforward.
Epiphora is an overflow problem. This could be caused by too much inflow, too little outflow, or both too much inflow and too little outflow.
Too much inflow
Too much inflow is common in the allergic patient, the patient with dry eye, blepharitis patients, the patient with ocular surface infection and patients recovering from facial nerve palsy. A good slit lamp exam may suggest one or more causes, and solving the underlying problem can solve the inflow problem. Asking patients whether the tearing is constant or intermittent, associated with discomfort, and whether the drops given by the tech for checking IOP have given them temporary relief directs us toward a possible cause.
If corneal anesthesia stops the tearing, the source of the reflex tearing should be sought. This may be as simple as some surface dryness or as complex as a corneal dysesthetic syndrome. Patients with “crocodile tears,” or tearing associated with aberrant regeneration of the facial nerve, often have worsening when eating. This is a problem easily treated with botulinum toxin injected directly into the lacrimal gland, but it must be distinguished from overflow due to surface dryness or poor outflow. Itchy, allergic patients can often be much happier with a regular regimen of a mast cell stabilizer/antihistamine combination. One must be particularly aware of patients with floppy eyelids and their host of ocular surface complaints, in addition to the significant possibility of patients suffering from obstructive sleep apnea.
Too little outflow
Too little outflow can be a congenital or acquired problem. There are two major components to outflow, namely the lacrimal pump and the patency of the lower lacrimal system. Either or both may contribute to the patient’s problem.
The lacrimal pump relies on proper geometry of the lid, conjunctiva and upper drainage system (puncta and canaliculi). Horner’s muscle and the remainder of the orbicularis surround the lacrimal sac, and when blinking occurs, they are thought to compress the sac and create a small negative pressure gradient as the eye reopens. If there is a lax lower lid, conjunctival obstruction of the punctum, or punctal or canalicular stenosis, this vacuum may not be enough to overcome the excess resistance, and the pump will fail to funnel the tears into the nasolacrimal duct.
If there is mechanical obstruction of the lacrimal duct (in adults, most often as a result of scarring, and in children, due to an imperforate valve of Hasner), no flow will occur into the nose. When irrigating a patient’s lacrimal system, the presence of reflux proves there is an obstructive component to poor outflow, but the lack of reflux does not similarly prove lack of obstruction. There is sometimes enough resistance in the outflow tract that the pressure generated by the syringe will easily overcome this, but the approximately 4 mm Hg generated by the natural pump will not. There is also the possibility of lacrimal system stones, which will be easily penetrated by the cannula or the saline will flow around them. Comparing the patient’s dye disappearance to the other eye and to the results of injection of saline will allow a more complete understanding of what is anatomic obstruction and what is functional obstruction.
When both too much inflow and too little outflow are present, a step-wise approach is indicated. If the patient has reflex tearing, the cause of this must be treated. If there is unrelated overproduction, Botox (onabotulinumtoxinA, Allergan) injected directly into the lacrimal gland may be used. For the patient with poor pump function, proper position of the lower lid should be re-established. If conjunctival chalasis is present, this may be either a source for overproduction or an obstruction to outflow and can be surgically treated. Three-snip punctoplasty is effective for punctal stenosis and can be performed in the office.
The other more distal causes of outflow obstruction require a trip to the operating room. Canalicular stenosis can be addressed with bicanalicular silicone intubation, particularly early narrowing caused by 5-fluorouracil or docetaxel. Common canalicular stenosis can be more stubborn, but an attempt may be made with the same type of tubes. If there is complete canalicular obstruction, often a Jones tube is necessary, and the patient must understand the potential complications of a permanently placed glass tube. Lacrimal sac or duct obstruction requires a dacryocystorhinostomy, either external (as when a mass or stone is suspected) or endoscopic (with or without silicone stent placement).
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- For more information:
- S. Tonya Stefko, MD, is an assistant professor of ophthalmology at UPMC and the University of Pittsburgh. She can be reached at University of Pittsburgh, UPMC Eye Center, Eye & Ear Institute, 203 Lothrop St., Floor 6, Pittsburgh, PA 15213; email: firstname.lastname@example.org.
Disclosure: Stefko reports no relevant financial dislcosures.