Sometimes our eyelids involuntarily move why
Inward turned lid (entropion) - causes
Entropion can have several causes. Most often, due to age, the lower lid turns inward
Why is the normal position of the eyelids so important?
The upper and lower eyelids are the most important protective organs of the eye. Put simply, the eyelids are skin folds reinforced by connective tissue and equipped with fine muscles. The blink reflex protects the eyes from foreign bodies and strong light.
And: With every blink of the eye, the eyelids distribute the tear fluid evenly over the eye, so that a protective film forms on the surface. It protects the eye from damage caused by dehydration and infection. Incidentally, we are hardly aware that our eyes blink several times per minute.
Inside the eyelids, close to the inner edge of the eyelid, are the meibomian glands. They form a fatty secretion (sebum) that cares for the lids and eyelashes and is important for the composition of the tear fluid.
With an entropion, the normal shape of the eyelid gap changes. This will affect the various protective functions. In other words: good eyelid closure requires normal eyelid positioning. Deviations not only disturb the appearance, i.e. cosmetically, but also the sight. Sometimes they even endanger the eye.
Entropion: There are four forms
- Age-related entropion (senile or involutive entropion; involutive means regression)
- Spastic entropion caused by cramping of the eyelid (Entropium spasticum), for example after an operation or in the case of an eye infection
- Scar entropion: from scars on the inner eyelid (Entropium cicatriceum)
- Congenital entropion (Entropium congenitum)
By far the most common entropion occurs in old age, increasing from about 70 years onwards. The lower eyelid in one or both eyes is almost always affected. At a young age, the "hanging device" of the eyelids is taut. This is how he keeps them in shape and position. Supporting structures play an important role here, such as the connective tissue plate in the eyelids called the tarsus and the two eyelid ligaments in the inner and outer corners of the eye. There they connect the eyelids with the periosteum. In addition, there are the orbicularis muscle and other muscles, the so-called Retractors. The orbicularis muscle is the ring-shaped eyelid closure muscle, or sphincter muscle for short. The retractors are small muscles anchored to the cartilage of the eyelid.
As you get older, these structures can change. Put simply, the suspension of the eyelid slackens and it becomes unstable. On the one hand, this is due to the connective tissue. On the other hand, the eyelid muscles also change. When the tension in the retractors on the lower eyelid eases, the sphincter muscle can become overweight. Its fibers move upwards towards the edge of the lid, with the result that the lid tilts inward. This is promoted by the fact that the eyes go deeper into the eye sockets in old age.
Spastic entropion is caused by cramping of the eyelids (spasmodic eyelid closure or blepharospasm). Possible causes are, for example, a painful inflammation, eyelid swelling or injury to the eye. Spastic entropion sometimes occurs even after eye surgery.
The sphincter muscle is convulsively contracted. The associated inward rotation of the lid recedes when the shutter release is removed. This means that the eyelid suspension itself is basically intact. Young people are more often affected. However, even with age-related entropion (see above) there is often an additional spastic component due to an accompanying eyelid cramp. Because of this, it is sometimes classified as spastic entropion, but that is not correct.
In addition to causes of the eyes, neurological disorders, for example so-called focal dystonia, are sometimes considered. It is characterized by involuntary bad posture or uncontrolled movements in a certain area of the body.
Scar Entropium (Entropium cicatriceum)
After injuries, for example chemical burns or mechanical damage to the eye, or in the case of inflammatory diseases of the conjunctiva and eyelids (doctors call this blepharoconjunctivitis), scars harden the elastic connective tissue of the eyelid. As a result, it shrinks and a scar entropion can develop. This is possible on both the lower and upper eyelids. Sometimes a scar entropion is due to adhesions. The eyelid conjunctiva can be fused with the eyeball conjunctiva or, to put it simply, the lid with the eye (technical term: symblepharon).
The most common form of scar entropion is due to a trachoma. This is an eye infection with bacteria called Chlamydia trachomatis, which is mainly found in tropical countries. It often affects the upper eyelid. Around eight million people fall ill worldwide, mainly in developing countries. There, the infection is still one of the most common causes of blindness, especially in children.
Other diseases play a role for us. Herpes zoster virus infections of the eye, allergic-inflammatory reactions of the skin, mucous membranes, conjunctiva and eyelids, as well as so-called autoimmune diseases, are associated with an increased risk of scar-related eyelid misalignments.
An example of a severe allergic reaction of the mucous membrane, skin and conjunctiva is Stevens-Johnson syndrome. Triggers are mainly medication, and less often certain infectious diseases or diseases of the lymphatic system. Pronounced, cockade-shaped, reddened skin blisters as well as blisters and ulcers develop on the mucous membranes. The conjunctiva react accordingly in the eye. In short, this can lead to tissue shrinkage.
In the case of an autoimmune disease, the immune system attacks structures in its own body that ignite in the fog. A disease from this group that can lead to scarring in the conjunctival vault of the eye is bullous pemphigoid (bullous means blistering). Accordingly, it is one of the blistering skin diseases. Older women are more likely to be affected. In the eyes, the inflammatory processes target the conjunctiva. The eyelid conjunctiva can eventually overgrow onto the cornea (see above: Symblepharon). Certain eye medications can also trigger a bullous pemphigoid. If the connection is clearly clear, the ophthalmologist will decide how the treatment can be changed. Operations on the eye can also influence the clinical picture.
Entropion is seldom innate. Both the upper and lower eyelids can also be affected here. Often the "eyelid suspension" is insufficiently developed. Sometimes the interplay between the eyelid muscles and nerves does not work properly. The change is usually harmless, as the infant's soft eyelashes hardly irritate the eye. The deformity usually normalizes in the first year of life. If this is not the case or if there are complaints, a correction is necessary.
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