When your eyes well up, whether from emotion, an irritant, or simply a yawn, and that familiar burning sensation follows, it can be quite perplexing. This common, uncomfortable experience often prompts questions about why tears, which are meant to lubricate and protect the eyes, sometimes cause such irritation. Understanding the underlying reasons behind this sensation involves exploring how external factors, the eye’s natural defenses, and the very chemistry of tears interact.
External Irritants and Allergic Reactions
Environmental factors frequently trigger reflex tearing and a burning sensation. Substances like smoke, dust, pollution, and strong chemical fumes can directly irritate the delicate surface of the eye. When these irritants come into contact with the eye, they stimulate nerve endings in the cornea and conjunctiva, prompting a rapid production of reflex tears to wash them away. This protective response can lead to a temporary burning or stinging feeling.
Allergens like pollen, pet dander, or mold spores initiate a similarly irritating response. When these tiny particles enter the eye, the immune system identifies them as threats. This triggers the release of chemicals, notably histamine, from mast cells in the eye. Histamine causes blood vessels in the conjunctiva to dilate and become leaky, leading to inflammation, redness, and itching, which can cause a burning sensation. Inflammation can also disrupt the tear film’s stability, further intensifying the discomfort.
The Paradox of Dry Eye Syndrome
One of the most common and counterintuitive causes of burning tears is dry eye syndrome (DES). This condition arises when the eyes do not produce enough tears, or the tears produced are of poor quality and evaporate too quickly.
The tear film, which covers the eye’s surface, consists of three layers: an inner mucin layer (adhesion), a middle aqueous layer (moisture), and an outer lipid layer (prevents evaporation). An imbalance in any of these layers can lead to dryness. If the lipid layer is insufficient, the aqueous layer evaporates too rapidly, leaving the eye exposed and irritated.
This chronic dryness then sends a signal to the brain, prompting the lacrimal glands to produce a flood of reflex tears. These “paradoxical tears” are often watery and lack the proper balance of oils and mucins needed for effective lubrication. Consequently, these poor-quality tears, though abundant, fail to soothe the dry eye, and their rapid production can contribute to the burning sensation.
Tear Film Chemistry and pH Imbalance
Beyond external factors, tear chemical composition can contribute to burning. Tears maintain a specific pH balance and contain electrolytes, proteins, and enzymes. Deviations from this balance can irritate the ocular surface. For example, the normal pH of tears is slightly alkaline, and if this balance shifts too much, either more acidic or more alkaline, it can cause discomfort and burning.
Changes in tear composition can occur during intense emotional crying. Emotional tears are distinct from basal tears (which lubricate the eye) and reflex tears (which clear irritants). They often contain higher concentrations of stress hormones, such as prolactin and adrenocorticotropic hormone, and certain proteins. The altered chemical makeup, combined with the increased volume of tears during emotional crying, can lead to a stinging or burning feeling.
An imbalance in tear osmolarity (concentration of dissolved particles like salts) can cause burning. When tear osmolarity is too high, often due to increased evaporation, it can irritate the eye’s surface and cause discomfort.
When to Seek Professional Advice
While occasional eye burning with tears is normal, certain symptoms warrant professional medical attention. If burning is persistent, severe, or accompanied by other concerning signs, consult an eye care professional.
These symptoms include significant eye pain, vision changes, persistent redness, or unusual discharge. Light sensitivity with burning, or a persistent feeling of something in your eye, also suggests evaluation. An eye doctor can diagnose the cause of your symptoms and recommend treatment to alleviate discomfort and prevent long-term issues.