Anatomy & Organs

Tears – structure, function & diseases


Tears are mostly only noticed in certain situations where people get emotional and cry. They also take on important functions and are always present in a healthy eye.

What are tears

Tears are fluid produced in the tear ducts . They form a thin layer that covers the cornea . The so-called tear film has numerous tasks and functions. The tear fluid is evenly distributed in the eye and separates the cornea and eyelid from each other.

People blink every four to six seconds. When blinking, the tear fluid gets into the eye as a lubricant. Before dry spots can appear, new tears are formed and these are distributed by blinking again. For example, it is possible to protect the eye from infection and pain caused by a dry cornea.

The tear film consists of several layers that are structured differently. In addition, it does not measure the same thickness in the different regions of the eye. Different diseases affect tear production and lead to different symptoms.


The various ingredients are produced in differentiated glands . The basic production of an adult human is 1.2 microliters per hour. If the eye is exposed to certain stimuli, more tears form. Tears consist of about three components that are present in layers within the eye. First, some glands produce mucus. This is also called mucus.

It ensures that the cornea becomes slippery. This is the only way that the following layer of water can stick to the eye. Otherwise the tear film would roll off. The middle layer follows the mucin layer. This consists of saline water and is responsible for most of the beneficial effects of tears. When there is a stimulus, only this layer is increasingly produced in the large lacrimal glands.

The last layer of the tear film consists of lipids. If the thin layer of fat is uneven or other conditions are present, vision is impaired. The lipid layer is produced by the meibomian glands and also forms the outer layer of the tear film. In order for the tear film to function properly, the layers must be optimally matched to each other. As soon as bumps appear in a layer, there are usually complaints of various natures.

Function & Tasks

Tears have different functions. In emotional situations, people often find crying to be a relief. Various emotional stimuli can lead to increased tear production. People cry not only out of grief, but also out of anger, desperation, overwhelm or pity. So far, scientists have not been able to reconstruct the exact process.

So it is not known why people cry. The theory that crying protects against depression is also not empirically proven. However, the function of tears in the eye is scientifically recognized. The thin tear film protects the cornea from gusts of wind and pathogens such as viruses and bacteria . The conjunctival sac and the outer cornea are regularly cleaned by the tears .

In addition, the tears function as a lubricant between the eye and the skin of the lid. This is the only way to ensure smooth blinking. If foreign objects get into the eye, more tears are produced to remove them. The middle layer of the tear film is particularly important in this process. In addition, it keeps the eye constantly moist and supplies the cornea with important substances.

These include oxygen. In the water layer are also the defense substances, which prevent the penetration of bacteria and other pathogens. In addition, tears play an important role in vision. They help ensure that the light can be optimally refracted. Especially if the outer layer is not smooth or has gaps, even putting on the glasses will not help to optimize vision.

Illnesses & Ailments

In everyday life, tears are usually only noticed when the body is not producing enough of them. Various factors, such as heating air or cigarette smoke, can dry out the eye. A change in the composition of the tear film is fundamental to dry eyes . If the composition or quantity is disturbed, the protective surface is no longer available.

The layers build on each other. If one of them is of poor quality or the quantity is not optimal, the stability and smoothness of the entire tear film is at risk. Instead, there are cracks and dry patches that are no longer surrounded by the tears. Numerous complaints result from dry eyes. Disrupted tear production can be caused by various lid diseases and inflammation of the lid margins .

This is often caused by an infection with bacteria. The sebaceous gland of eyelashes is affected. Tumors , misalignments, inflammation and cosmetic problems such as eyelid cysts come into consideration as eyelid diseases Correcting the symptoms mentioned can be suitable for treating dry eyes.

If no disease-related factors could be determined, artificial eye drops , which must be used at regular intervals, can help. It’s not uncommon for dry eyes to turn into a chronic process. In addition to dry eyes, there can also be an increased production of the water layer.

Watery eyes are triggered by different mechanisms. These include, for example, a disturbance in the drainage of tears. In addition, there may be an overproduction of tears or changes in the tear ducts. In women in particular, watery eyes occur as part of hormonal changes, such as during menopause. In the event of a temporary overproduction, inflammation of the large lacrimal gland is a possibility .

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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.