The experience of having tears stream down your face without emotional cause is medically known as epiphora. This condition is defined as the overflow of tears onto the cheek, occurring when the body’s natural balance between tear production and drainage is disrupted. Epiphora is a physical symptom resulting from a physiological issue within the lacrimal system. The underlying problem is generally categorized into two main groups: the eye either produces too many tears, or the normal channels for tear drainage are impaired.
When the Eye Makes Too Many Tears
The eye is equipped with a defense system that triggers an immediate flush of fluid in response to a perceived threat or irritant. This response is called reflex tearing, representing an overproduction of tears designed to wash away foreign substances. These tears come from the large lacrimal gland, located above the outer corner of the eye. External factors are common triggers for this hypersecretion. Exposure to environmental irritants like wind, cold air, smoke, or dust can activate the reflex, and even bright light can sometimes stimulate the nerves responsible for this protective mechanism. Reflex tearing is typically more watery and copious than the basal tears, which are constantly produced for simple lubrication. When an irritant is detected, the lacrimal gland generates a massive volume of tears, overwhelming the eye’s normal drainage capacity. This results in the excess fluid spilling over the eyelid margin and running down the cheek.
Issues with Tear Drainage
Tears that are produced normally must exit the eye through a specialized system, and a failure in this drainage pathway is a frequent cause of epiphora. Tears typically collect at the inner corner of the eye and enter two tiny openings called the puncta, one on the upper eyelid and one on the lower. The puncta are the entry points to the lacrimal drainage system.
From the puncta, tears travel through small channels called the canaliculi, which lead into the lacrimal sac near the nose. The tears then proceed down the nasolacrimal duct before finally draining into the nasal cavity. Obstruction can occur at any point along this route, preventing the tears from clearing the ocular surface. For instance, the puncta openings can become narrowed (punctal stenosis), which restricts tear inflow. A blockage further down in the nasolacrimal duct is also a common issue, often caused by inflammation or scarring. If the tears cannot drain through this system, they overflow onto the face, even if tear production is at a standard rate.
The Paradox of Dry Eye Syndrome
One of the most confusing causes of persistent watering is dry eye syndrome, which can seem contradictory to the symptoms of tearing. Dry eye often stems from a poor quality of tears rather than an insufficient quantity. The tear film is composed of three layers, including an outer oily layer produced by the meibomian glands.
If the oily layer is deficient, the aqueous layer of the tears evaporates too quickly, leading to evaporative dry eye. This rapid evaporation causes the surface of the eye to become irritated and dry. The eye interprets this dryness and irritation as a threat. The nervous system triggers the lacrimal gland to produce a massive, immediate rush of reflex tears. These “emergency” tears are mostly water and lack the necessary oil and mucus components for proper lubrication. Because they are poor quality and produced in excess, they quickly spill over the eyelid, creating the symptom of excessive watering. This creates a cycle where the underlying dryness causes the eye to over-water.
Inflammation and Structural Causes
Beyond issues of tear quantity and drainage, inflammation and changes to the eyelid structure can also lead to epiphora. Conditions that cause chronic inflammation of the eyelid margins, such as blepharitis, can irritate the ocular surface, prompting the eye to produce reflex tears. Allergies are another common inflammatory trigger, causing irritation and watering.
Structural problems that affect the position of the eyelid are often seen in older adults and can interfere with the drainage process. Ectropion is a condition where the lower eyelid turns outward, causing the punctum to lose contact with the tear film. Conversely, entropion is when the eyelid turns inward, causing the eyelashes to rub against the cornea, which stimulates constant reflex tearing. Persistent, involuntary tearing should be evaluated by an eye care professional for accurate diagnosis and treatment.