Have you ever walked outside and suddenly everyone is wondering why tears are streaming down your face, and even more peculiarly, only down one side of your face? Perhaps the sight of a beautiful blue sky moved you to tears, or perhaps you are just experiencing a bit of epiphora. Though a watering eye, also known as epiphora, itself is not harmful, sometimes it can be a symptom of something else that needs addressing. As the tear film is the first refractive surface that light meets when entering the eye, an overflow of tears can cause blurred vision, which can be inconvenient, such as when driving or trying to watch your bride walk down the aisle towards you, and on occasion can also be a little embarrassing.

 
The Usual Bullies – Causes of Watery Eye
There are some obvious causes of a watery eye, one being that your bride decided she didn’t want to be with you after all and you are now nursing a broken heart; another potential reason is that you’ve recently been assaulted by a chopped onion; still another is that your toddler just poked you in the eye, as toddlers do. The other usual suspects for an eye overflowing with tears include:

• Viral conjunctivitis – this often presents with other telling symptoms, including redness and a burning or itching sensation of the eye
• Infection or inflammation of the cornea – the cornea is a very sensitive part of the eye and any sort of keratitis (inflammation of the cornea) can trigger tearing alongside blurred vision, pain, and redness
• Blepharitis – this is inflammation of the eyelids and often results in irritants, such as bacterial waste products, dead skin cells, and mite infection byproducts, falling onto the surface of the eye from the lids. The ocular surface irritation stimulates the production of tears
• A foreign object in the eye – the foreign object doesn’t have to be as large as a toddler’s finger to irritate your eye and start the flow of tears; it can be even a tiny seed that found its way into your eye during a gardening session, an eyelash or a fine cloth fiber
• Allergies – if you’ve ever been on the receiving end of the wrath of hay fever then you know crying comes part and parcel with the experience. Other symptoms are likely to be present with this depending on the severity of the allergic reaction, including itching, sneezing, and red, swollen eyes

 
The More Unexpected But No Less Common and Annoying Culprits

Often there can be no straightforward explanation for your watery eye – you’re happily married with grown children who have moved past the eye-gouging age, your eyes aren’t red or sore or itchy, and you hired a gardener. Why does your eye keep watering out of the blue?

The lacrimal (tear) system is not as simple as a little gland squirts out tears into your eye and then the tears somehow eventually disappear until the next squirt of tears. Many factors, most of them anatomical, play a big role in balancing the production and drainage of tears in the eye. A well-behaved lacrimal system looks something like this: the lacrimal and accessory lacrimal glands of the upper eyelid, meibomian glands at the eyelid margins, and goblet cells of the conjunctival epithelium secrete their contributions of the tear film onto the surface of the eye; blinking helps to spread this tear film across the eye as well as stimulates further secretion of the tear components, while also pumping existing tears towards the drainage channels. Tears are pushed towards two tiny holes on the inner lid margin corners, known as puncta, and then flow through little tubes known as canaliculi into the lacrimal sac and down the nasolacrimal duct, draining through the back of the nose and then are reabsorbed. As the lower eyelid can only really hold up to about 8 to 10 microliters of tears at any time, any disruption to this delicate balance of tear production and drainage and next thing you know, you’re crying for no reason. Well, pull yourself together, man. It can be fixed.

 
Abnormal eyelid position and function
Loose and lax eyelids, particularly lower eyelids, not only form a poor reservoir to hold tears but also don’t do a great job at pumping tears towards the puncta during blinking. An eyelid not held taut against the eyeball may also result in the actual punctum itself not sitting against the eye, which means tears have a hard time getting into the drainage system and end up overflowing instead. The most common examples of such eyelid abnormalities are ectropion (the eyelid margins flop outwards), entropion (the eyelid margins turn inwards), floppy eyelid syndrome (an oddly named condition that is exactly as it sounds), and Bell’s palsy (damage to the facial nerve that controls blinking). Because the face is often not quite symmetrical, most patients will find the epiphora occurs only in one eye, or is noticeably worse in one than the other.

Ectropion, entropion, and floppy eyelid syndrome can arise from a number of reasons, the most common of these being age. Luckily, they are often easily addressed with surgery that can restore the proper position and tautness of the eyelids. Bell’s palsy is a weakness of the facial nerve, which results in an inability to properly close the eye on the affected side. While the palsy is resolving, the eyelid may need help with blinking, such as with surgically implanted weights or by just temporarily patching the eye closed to protect it.

 
Ocular surface disorders 
Any bumps or obstructions on the surface of the eye along the drainage pathway can interrupt the outflow of tears. This includes a common condition called conjunctivochalasis, which refers to a bunching or wrinkling of the conjunctival membrane. The folds of excess conjunctiva in the lower part of the eye can get in the way of tears accessing the punctum, leading them to spill over. Similarly, a conjunctival cyst or fold around the punctum itself will inhibit tears getting past. Cysts and excess conjunctiva can be fixed with a visit to the eye doctor, who can lance the cyst or surgically remove the wrinkled membrane (a bit like having a face lift – or an eyeball lift, if you will).

Irritation of the surface of the eye can stimulate reflexive tear production, tipping that delicate balance in favor of a good watery eye. Chronic blepharitis, tickling from ingrown eyelashes, or even dry eyes – yes, that’s right, dry eyes can trigger watery eyes – can induce the eye to produce an excess of tears. Epiphora as a result of dry eye can often be identified by tearing being worse at the end of the day after certain activities that exacerbate dryness, such as computer use or intense reading. Certain eyedrop medications, including the preservatives within them, can also cause irritation to the eye. Identifying what irritant may be stimulating this overproduction of tears is key to treating the epiphora, whether it’s removing the offending ingrown lash or starting you on a dry eye treatment regime; a visit to your eye doctor can help with this.

 
Lacrimal system obstructions
Less commonly, a physical obstruction may present itself somewhere along the lacrimal drainage system. These typically cannot be identified in a mirror, though if you have a huge swelling along the side of your nose on the side of the epiphora then you may figure you have a bit of an obstruction in there somewhere. With age, the puncta or canaliculi may narrow and inhibit the outflow of tears. Narrowing to these structures can also be a result of certain medications, chronic inflammation or infection, trauma, or radiotherapy. Certain autoimmune diseases, such as Stevens-Johnson syndrome and ocular cicatricial pemphigoid can cause these mucosal structures to scar and close off. Further down the drainage system is not immune to obstruction either – the nasolacrimal duct may become blocked from age-related narrowing, trauma, as a side effect of nasal surgery or radiotherapy, tumor growth, or infection and inflammation of the duct (known as dacryocystitis). Tearing as a result of a nasolacrimal duct obstruction tends to be worse when outdoors in the cold wind.

Again, the treatment will depend on the underlying cause of the obstruction and the location of the obstruction itself. A narrowed or disfigured punctum can be addressed with a surgical procedure called a punctoplasty, which serves to widen this aperture. On occasion a stent or tube may be inserted to keep the punctum and canaliculi open. Underlying autoimmune conditions, infections, or tumors should be treated accordingly with medications or surgery (and a watery eye will probably be low on the list of concerns in this situation).

For the most part, epiphora is but a mild bother when trying to play golf and many people opt simply to wipe away their tears and get on with life. For others, the one-sided crying during inappropriate situations is enough of a concern to warrant a visit to the eye doctor, who hopefully will be able to turn your single-sided tears of frustration into double-sided tears of joy.

References

What causes watering eyes (epiphora)? https://www.healthline.com/health/epiphora

The tearing patient: diagnosis and management. https://www.aao.org/eyenet/article/tearing-patient-diagnosis-management

Anatomy, head and neck, eye lacrimal duct. https://www.ncbi.nlm.nih.gov/books/NBK531487/

Evaluating epiphora: nothing to cry about. https://www.reviewofophthalmology.com/article/evaluating-epiphora-nothing-to-cry-about