The sensation of tears burning the eyes signals a disruption in the delicate balance of the eye’s surface. Tears are designed to be soothing and protective, not irritating. When burning occurs, it often indicates an underlying issue related to the tear composition or the presence of external irritants. Understanding the normal function of tears helps explain why they sometimes begin to sting.
How Normal Tears Protect Your Eyes
Normal tears form a thin, three-layered coating over the eye’s surface known as the tear film. This film provides a smooth surface for clear vision and protects against pathogens. The inner layer is the mucus layer, which anchors the tear film to the eye’s surface, ensuring the tears spread evenly.
The middle and thickest layer is the aqueous layer, composed mainly of water, electrolytes, and anti-bacterial proteins. This watery component provides lubrication and essential nutrients to the cornea. The outermost layer is the lipid, or oily, layer, secreted by the meibomian glands in the eyelids. This oil acts as a barrier, preventing the aqueous layer from evaporating too quickly.
When the Tear Film Becomes Unbalanced
The burning sensation arises when the quality of the tear film changes, irritating the sensitive corneal nerves. The most common cause is Dry Eye Disease, which results in a loss of the tear film’s normal balance. A primary factor in this discomfort is tear hyperosmolarity, meaning the tear fluid has become too concentrated or “too salty.”
This concentration occurs when the protective oil layer is insufficient, causing the aqueous layer to evaporate rapidly. This leaves behind a higher concentration of electrolytes and solutes. This hyperosmolar fluid stresses the cells on the eye’s surface and irritates nerve endings, causing the stinging sensation. Meibomian Gland Dysfunction (MGD) is a major contributor, as clogged glands produce poor quality oil, leading directly to increased evaporation and hyperosmolarity.
Environmental Triggers and Inflammation
External factors can cause tears to burn by inducing an inflammatory response or altering tear composition. Exposure to air pollutants, smoke, dust, or low humidity stresses the ocular surface, leading to increased evaporation and irritation. In response, the eyes produce large amounts of “reflex tears” intended to wash away the foreign substance.
While protective, these reflex tears sometimes contain a higher concentration of salt than normal tears, contributing to a temporary burning feeling. Allergic reactions are another common trigger, as the body releases histamine in response to allergens like pollen. This histamine causes inflammation on the eye’s surface, leading to redness, watering, and a distinct sting. Inflammation of the eyelids, known as blepharitis, can also cause burning by creating irritation near the meibomian glands.
Seeking Relief and Professional Advice
For mild, occasional burning, simple at-home measures can provide relief by restoring moisture. Over-the-counter artificial tears help re-lubricate the eyes and reduce the concentration of hyperosmolar tears. Applying a warm compress to the closed eyelids is beneficial if the burning is linked to Meibomian Gland Dysfunction, as the heat helps release blocked oils.
Maintaining adequate hydration and using a humidifier can also support eye moisture. If the burning sensation is persistent, does not improve with home care, or is accompanied by discharge, pain, or changes in vision, professional consultation is necessary. A specialist can perform tests, such as tear osmolarity measurement, to accurately diagnose the cause and recommend targeted treatments, including prescription drops or in-office procedures.