Composition of Tears 

Tears are composed of a complex mix of water, oils, proteins, and electrolytes, each playing an important role. Water for moisture, oils for lubrication and to prevent tear evaporation, and proteins and electrolytes to provide nutrients to the surface of the cornea. 

The intricate balance of components ensures that tears perform their function effectively, from protecting the eye against infections, providing comfort and nutrients, to facilitating clear vision.  

Types of Tears 

Did you know there are different types of tears, and not every tear has the same components?  

Tears can be categorized into three main types, each with a slightly different composition and serving a distinct purpose:  

• Basal Tears 

These tears are always present in our eyes, they contain layers of mucus, water and oil, to maintain moisture, nourish the cornea, and lubricate the eyes to prevent dryness, irritation and focus vision. 

• Reflex Tears 

Triggered by irritants like foreign bodies, dryness, allergies or strong winds, reflex tears are the body’s immediate response to protect the eyes. They flush out irritants and foreign particles, preventing potential damage. They are produced in response to discomfort, aiming to temporarily alleviate symptoms by adding moisture to the surface of the eye. However, these tears contain more water and lack the necessary components to provide long-term relief or effective lubrication.  

• Emotional Tears 

When we cry due to emotions, whether joy, sorrow, or stress, the composition of these tears also differs from basal or reflex tears. Studies have found that emotional tears also contain hormones and endorphins.   

Disorders Related to Tears 

Disruptions in tear production or quality can lead to having too many or not enough tears, and both can result in damage to your eyes if left untreated. Some common conditions include:   

• Dry Eye Syndrome (Aqueous Deficiency)  

This occurs when the eyes do not produce enough tears or when tears evaporate too quickly. It leads to a lack of moisture and lubrication on the surface of the eye, causing discomfort, redness, gritty sensation, and blurred vision. This often triggers reflex tears, that lack the necessary components to provide proper lubrication and leads to a combination of dryness and watery eyes in some cases.  

• Meibomian Gland Dysfunction (Evaporative Dry Eye) 

Meibomian glands produce the oily component of tears that prevent evaporation. When these glands don’t function properly, the tear film becomes unstable, leading to increased evaporation of tears and dry eye symptoms. Without an oily surface layer, the aqueous tears are exposed to the air and evaporate more quickly.  

• Sjogren’s Syndrome 

An autoimmune disorder where the immune system attacks the body’s moisture-producing glands, leading to dryness in various parts of the body, including the eyes and mouth. In this condition there is a reduced production of tears, and can lead to aqueous deficiency and severely dry and inflamed eyes. 

• Blocked Tear Ducts 

When the drainage system for tears is obstructed, tears cannot drain properly from the eye. This obstruction can lead to excessive tearing and the increased volume of tears overwhelms the drainage capacity, causing overflow onto the cheeks.