The sudden rush of tears experienced when stepping outside on a chilly day is known medically as cold-induced epiphora. This excessive tearing is a common, harmless physiological reaction, not caused by emotional distress. It is a protective mechanism triggered by the body’s attempt to maintain the health of the eye’s surface. This reaction involves two distinct processes: the overproduction of tears and the failure of the tear drainage system to keep up.
The Reflex Response to Cold Air
The primary driver of watery eyes in cold weather is an overproduction of fluid, a defensive measure called reflex tearing. When the eye is exposed to cold, dry air or wind, moisture on the corneal surface evaporates at an accelerated rate. This rapid drying and temperature drop irritate the delicate nerve endings of the cornea.
This irritation sends a signal through the trigeminal nerve to the brainstem, initiating a protective response. The nervous system then commands the lacrimal glands, located above the outer corner of each eye, to secrete a sudden flood of tears. The goal of this aqueous surge is to quickly wash away any potential irritants and provide a fresh layer of lubrication to the dried ocular surface.
Paradoxically, this reflex is often a response to the eye becoming too dry, a condition sometimes termed paradoxical dry eye. The tear film becomes unstable in the face of wind and cold. The resulting poor-quality tear film is sensed as a lack of moisture, prompting the release of a large volume of watery tears in a compensatory effort to stabilize the surface.
Why Tears Overflow
While reflex tearing explains the high volume of fluid, the reason the tears spill onto the cheeks relates to a temporary failure of the drainage system. Tears normally flow across the eye’s surface and collect at the inner corner, where they enter two small openings called puncta, located on the upper and lower eyelids. From the puncta, tears travel through tiny channels into the nasolacrimal duct, which drains directly into the nasal cavity.
The high volume of tears produced by the reflex response simply overwhelms the capacity of this drainage system, leading to overflow, which is a form of obstructive epiphora. Furthermore, cold temperatures and wind can cause a temporary swelling or congestion of the mucous membranes surrounding the nasolacrimal duct. This swelling narrows the already small drainage pathway, similar to how nasal passages become blocked during a cold.
This combination of excessive tear production and reduced drainage efficiency means the fluid has nowhere to go but over the eyelid margin and down the face. Even a slight, temporary constriction of the duct can become noticeable when the lacrimal glands are working overtime in the cold.
Simple Ways to Prevent Watering Eyes
Managing cold-induced epiphora involves strategies that address both the irritation and the drainage issues. The most effective approach is to create a physical barrier between the eyes and the harsh environment. Wearing wrap-around sunglasses or goggles provides a shield against the wind and cold air, significantly reducing the stimulus for reflex tearing.
Choosing protective eyewear that blocks wind from the sides helps to maintain a pocket of warmer, more humid air around the eyes, slowing tear evaporation. Additionally, covering the face with a scarf, balaclava, or hat with a brim can further reduce direct exposure of the eyes to gusting wind.
Using lubricating eye drops, often called artificial tears, before going outdoors can also be helpful. These drops supplement the eye’s natural tear film, providing a layer of moisture that helps prevent the initial dryness and irritation that triggers the reflex tearing. Consistent hydration by drinking water throughout the day contributes to overall body and eye moisture. Inside the home, using a humidifier during winter can help maintain a comfortable level of humidity.