Definition of dry eyes
Dry eyes are usually a disturbance of the tear film. As a result, the conjunctiva and cornea of the eye are incorrectly and insufficiently wetted. Dry eyes are caused by a wetting disorder of the ocular surface.
The cause is believed to be an incorrect composition of the tear fluid. Other basic diseases or medication can also be a possible cause. The affected persons mainly suffer from dryness and itching. Tear substitutes are mainly used for therapy.
Occurrence in the population
The dry eye occurs more and more often in older age. Women are generally more frequently affected than men.
Causes of dry eyes
The production of tear fluid follows a time-dependent rhythm and decreases towards the evening, for example. Apart from these fluctuations, there is also reduced tear production with disease value. A defective tear film is mainly responsible for the development of dry eyes.
Since the tear film consists of three different phases from the outside to the inside: The cause of dry eyes can be sought in all of the three layers. Depending on which type of gland is affected, a different phase of the tear film suffers: Usually, the volume of the tear gland decreases slightly over the years, which causes the aqueous phase to suffer. It is then produced in insufficient quantities.
If the meibomian glands of the eyelid no longer work completely, too little fat is produced. If the goblet cells of the conjunctiva do not function sufficiently, the proportion of the mucin phase is reduced. In addition to the sole functional disorder of the various types of glands, dry eyes are also a symptom of various underlying diseases: In the development of dry eyes, therefore, a variety of diseases can be causative.
Besides systemic diseases such as diabetes mellitus (“sugar”), neurological failures (paralysis of nerves) also play a role.
- Fat layer
- Aqueous layer
- Mucin layer
- Sjögren’s syndrome: Sjögren’s syndrome is a chronic inflammation of several joints with a reduction in the secretion of various salivary glands. Dryness of nose and mouth is also typical.
Here, the moistening of the eyes can be so severely disturbed that a corneal ulcer (ulcer = ulcer) develops. A breakthrough through the cornea can also occur. In this case a corneal transplantation is only useful if the humidification of the eye is ensured in the future (e.g. by tear substitutes). The development of dry eyes can therefore be caused by a variety of diseases. Besides systemic diseases such as diabetes mellitus (“sugar”), neurological failures (paralysis of nerves) also play a role.
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