Tear film – perfect protection for the organ of vision
The corresponding structures in our eyes produce tears all the time so that the eyeball can be coated with the so-called tear film. What is this and why is the tear film so important?
You are wrong to think that tears are secreted only when you cry. The proper functioning of the eye also depends on its constant optimal hydration, which is guaranteed precisely by the undisturbed secretion of the tear film.
What is a tear film?
Tear film is a very thin, natural protective layer that covers the front of the eyeball. It is made up of three layers:
- Lipid (fatty) layer – is the outer layer, produced by Meibom’s glands. It protects the eye from too rapid evaporation of water and impedes the overflow of tears over the eyelid margins.
- Aqueous layer – this is the middle layer, helping to flush out impurities and small foreign bodies that reach the surface of the eye. In its composition we can find m. in. proteins, enzymes and antibodies, which have cytoprotective (reducing the side effects of the most commonly used chemotherapeutics, i.e. drugs produced in the laboratory, rather than, for example, preparations of natural origin), anti-inflammatory and antimicrobial effects.
- Mucin layer – this is the inner, mucous layer, which ensures that the natural unevenness of the surface of the eye is evened out and that the entire layer of the tear film is thoroughly distributed on it and also facilitates the adhesion of water molecules to the outer layer of the cornea.
What happens when there are disorders in the secretion of the tear film?
The most common effect of abnormal tear film secretion is Dry Eye Syndrome (DSO). Dry Eye Syndrome, caused by a deficiency of the aqueous layer of the tear film, can occur either as a spontaneous condition/disorder or in the course of an autoimmune disease called Sjögren’s syndrome.
Approximately 80% of cases of Osteoporosis is a form with excessive evaporation of the tear film, induced mainly by abnormalities in the structure and function of the Meibom’s glands. The remaining 20% are associated with its improper composition (e.g., a significant increase or decrease in the thickness of one layer relative to the others) or too little tear film and a deficiency in its aqueous component.
Remember: chronic and untreated AS can lead to corneal epithelial erosion, followed by bacterial or sterile corneal ulcers, which are conditions that threaten vision loss.
Everything you want to know about the effects of tear film disorders on the development of Dry Eye Syndrome can be found here in this post.
What causes abnormal tear film secretion to occur?
Risk factors responsible for the appearance of tear film disorders include:
- Excessive use of screen devices (smartphone, laptop, TV, tablet) without taking appropriate breaks for rest and accommodative exercise;
- Staying too long in heavily air-conditioned rooms and vehicles;
- improper use of contact lenses, especially wearing them longer than recommended by the manufacturer;
- Ignoring eye and eyelid hygiene, such as touching them with dirty hands, excessive rubbing.
As you can see, these are factors over which you have influence. While sometimes you are not able to avoid the use of medications, which also exacerbate tear film secretion problems, and you have no control over genetic conditions, in all of the bulleted cases you can make a change in habits.
And one more thing. In diagnosing dry eye syndrome, questionnaires are invaluable for estimating the extent of the ailment and the number of symptoms. You will read about them here.
