What Glands Produce Tears and the Tear Film?

The tear film is a thin layer of liquid which covers the front of the eyes. These tears are produced by several glands in and around the eyes and need to be present to prevent dryness and other eye problems.
 

What is a Normal Tear Film?

A normal, or healthy, tear film is a full layer of thick liquid tears which cover the eyes. This tear film will produce a small area of pooling at the lower eyelid called a tear lake. In a healthy tear film, the tear lake will be a few millimeters tall and the entire front of the eye will be covered with tears after a blink. The tears should not begin to break apart until about ten seconds after a blink.  If the tear film is made of the appropriate components, in the correct amount, there are few reasons for the tear film to be abnormal. 
 

Components of the Tear Film

There are three main components of the tear film. There is a watery or aqueous component, a lipid or oil component, and a mucus component. The majority of the tear film is made of the aqueous portion as the goal is to have a slick, watery surface on the front of the eye. There is an oil component in the tears to prevent the tear film from evaporating off of the eyes too quickly. The mucus component of the tear film is needed to help hold the tear film onto the front of the eyes.
 

Glands that Make the Aqueous Portion of the Tear Film

As the biggest component of the tear film, the aqueous portion also has the largest glands to produce it. The lacrimal gland is a large gland that is above the eye and secrete onto the eye’s surface. The lacrimal gland is the main source of the aqueous component of tears. Additionally, there are accessory lacrimal glands found inside of the eyelid which help secrete the aqueous portion of the tear film. The lacrimal glands are responsible for making the majority of the tears and keeping the front of the eye lubricated. If there is a deficiency of the lacrimal glands, it can cause the tear film to be insufficient and very thin. 
 

Glands that Make the Oil Portion

The oil portion of the tear film is secreted by oil glands inside the eyelid called Meibomian Glands. These glands are found on both the upper and lower eyelids. The Meibomian Glands are responsible for producing enough oil to keep the tears from breaking apart too quickly and causing dryness between the blinks. 
 

Glands That Make the Mucus Portion

The mucus portion of the tear film is produced by goblet cells inside the clear membrane on the eye called the conjunctiva. These goblet cells secrete a mucus-like liquid directly into the tear film. The mucus is needed to keep the tear film loosely attached to the front of the eyes. If there is a lack of the mucus component, the tear film will not adhere to the eyes and the tears will overflow onto the cheeks but will still cause dry eyes.
 

Importance of the Tear Film

The tear film as a whole is the biggest factor in dry eyes. It is important that all of the glands that contribute to the tear film are functioning and producing the correct amount and type of tears. If there is an imbalance or problem with any of these glands, there can be symptoms of dry eyes that require treatment. 

Our eye doctor at The Optical Centre in Longmont, CO excels in prescription of glasses, contact lenses and the diagnosis of a variety of eye diseases. Call our optometrist at 303-772-6650 or schedule an eye exam appointment online if you would like to learn more about the importance of a healthy tear film. Our eye doctor, Dr. Erica Whitmire provides the highest quality optometry services and eye exams in Longmont, Colorado and its surrounding areas.

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