The inability to produce tears, or to cry during intense moments, can be confusing. Tears are a complex biological fluid that forms a critical component of eye health, not just an emotional outlet. A deficiency in tear production or quality can stem from physical problems with the glands, side effects from common medications, or neurological and psychological factors.
The Three Roles of Human Tears
The human body produces three distinct types of tears, each serving a separate function for eye health.
Basal Tears
Basal tears constantly coat the eye surface to keep it lubricated, nourished, and protected from dust and bacteria. This continuous, low-level secretion is essential for maintaining a smooth optical surface necessary for clear vision.
Reflex Tears
Reflex tears are produced in response to sudden irritants, such as smoke, foreign particles, or onion fumes. These are released in a larger volume than basal tears and act as a rapid flushing mechanism to wash away potential harm. They also contain increased levels of antibodies to help fight off any bacteria that may have entered the eye.
Emotional Tears
Emotional tears are triggered by strong feelings, whether sorrow, joy, or extreme pain. These tears can contain higher concentrations of certain stress hormones and proteins. This suggests they may act as a mechanism for releasing these chemicals and promoting emotional regulation.
When Tear Production Fails: Aqueous Deficiency
A major physical cause of tear deficiency is a reduction in the production of the aqueous, or watery, component of the tear film, called aqueous-deficient dry eye (ADDE). This water content is primarily produced by the lacrimal glands located above the eyes. When these glands fail, the entire tear film is compromised, leading to symptoms like a gritty sensation, burning, and redness.
Age is a common factor, as tear production naturally diminishes after the age of 50. Certain medications also interfere with lacrimal gland function, including antihistamines, decongestants, and some antidepressants. These drugs have a drying effect on mucous membranes throughout the body, including the glands that produce tears.
Systemic autoimmune diseases are another cause of ADDE. Sjögren’s syndrome is a chronic disorder where the immune system mistakenly attacks moisture-producing glands, including the lacrimal and salivary glands. This condition, often associated with rheumatoid arthritis, directly destroys the ability of the glands to produce sufficient water content for tears.
When Tears Evaporate Too Quickly: Evaporative Dryness
Tear deficiency is often a problem of quality rather than quantity, leading to evaporative dry eye (EDE). This occurs when the tear film is unstable and evaporates too quickly, even if the watery layer is produced normally. The stability of the tear film depends on its outermost layer, which is made of oil, or lipid.
The lipid layer is secreted by small glands within the eyelids called Meibomian glands. The primary cause of EDE is Meibomian Gland Dysfunction (MGD), where these glands become blocked or inflamed. When the oil layer is compromised, the underlying water layer is exposed to the air and evaporates rapidly.
MGD can lead to a cycle of dryness, inflammation, and further gland dysfunction. This type of dry eye can sometimes cause the eyes to water excessively as the lacrimal gland attempts to compensate for the rapid evaporation. However, these reflex tears lack the necessary oil barrier and quickly disappear.
The Inability to Cry Emotional Tears
The inability to shed emotional tears is a distinct phenomenon separate from physical dry eye conditions. This issue is often rooted in neurological or psychological factors that disrupt the brain’s ability to translate emotional signals into a physical weeping response.
Certain mental health conditions, such as severe depression, can lead to emotional numbness, where the intensity of feeling is dulled and does not trigger crying. Past emotional trauma or chronic stress can also cause a psychological suppression of emotions, acting as a defense mechanism. This learned behavior can become automatic, leading to a neurobiological disconnection between the emotional state and the physiological tearing response.
Individuals with conditions like Alexithymia experience difficulty identifying and expressing their emotions, which prevents the emotional trigger for tears. Additionally, certain medications, particularly selective serotonin reuptake inhibitors (SSRIs), can cause emotional blunting as a side effect.