Eyelid
Our eyelid protects the sensitive eye and therefore one of our most important senses. The medical term is palpebrae. What is the exact structure of the eyelid, when does it close and which diseases limit its function?
Definition
Eyelids play a crucial role in determining the appearance of humans and animals. They are part of the facial muscles. Changes to the usual function of the eyelids are immediately perceived by the other person as disturbing. The eyelids protect the eyes, which are in need of protection, even in extreme situations.
Anatomy
The eyelids consist of an upper and lower part, the upper and the lower lid. There is also the visible outer area and an inner area of the eye. The visible area consists of two muscles , the lid closure and the lid lifter.
The skin of the eyelid is above the muscles. Inside you will find a connective tissue plate, the tarsus. It is made up of collagen fibers that give the eyelid its shape. The glands located there, called Meibim’s glands, secrete the oily part of the tear fluid, which is responsible for its lubricity. There are about 30 pieces in each eye.
In addition, we find sweat and sebaceous glands towards the edge of the eyelashes . If we close the upper and lower eyelids, there is a gap or a visible line where the two touch. This is the crease. The area where the upper and lower eyelids connect is called the canthus.
Function
The skin folds of the eyelid ensure that we can close our eyes. In addition to providing mechanical protection against foreign matter, air and light, the eyelids also play a further role. They keep your eyes wet.
In order to ensure immediate protection, the closing of the eyelids is not exclusively conscious. The blink reflex kicks in when suddenly struck by foreign objects such as dust or another person’s finger. The eyelids also close reflexively in the event of sudden exposure to light and loud noises. The blinking reflex is also called the corneal reflex because it is triggered by irritation of the cornea . Both eyes always close. Of course, the protective function also exists during sleep.
The cornea must always be kept moist and clean. Like the blades of a windscreen wiper, the eyelids disperse tears and remove debris. The wiping or blinking normally takes place 12 to 15 times per minute. The wiping frequency increases, for example, when you are nervous. It drops to around half when we concentrate on a visual process with our eyes, for example when watching television.
Diseases
- twitching
- Facial palsy
One of the most common eyelid dysfunctions is eyelid twitching. This annoying twitching can have several causes. It’s often [stress] related, triggered by lack of sleep or overstimulation. Inflammation of the conjunctiva can also cause eyelid twitching.
Inflammation of the eyelid margin (blepharitis) is also very common. The clearest sign of this are the sticky eyes in the morning. The eyes themselves often burn and are red. The cause of eyelid edge inflammation is usually a bacterial infection (often with staphylococci) or a dysfunction of the glands in the eyelids.
The classic glandular disorder of the eyelid leads to stye. In technical jargon it is called the hordeolum. Here, too, it is often the staphylococci germ that triggers inflammation of the sebaceous and/or sweat glands. The stye is a punctate swelling and reddening, usually with a yellow core. The stye is particularly unpleasant when glands on the inside of the eyelid become inflamed. The friction and thus the feeling of a foreign body are particularly high here.
The hailstone, which is also very common, has another cause. Secretion builds up in the large sebaceous glands in the connective tissue. In contrast to the stye, the chalazion is usually painless because there is no inflammation.
Xanthelasma, light yellow deposits, usually on both eyes, are common and also painless, although very noticeable. Cholesterol tends to build up in the outer lid. The deposits themselves are not dangerous, but they can indicate an existing lipid metabolism disorder. The psychological pressure, on the other hand, is often high with xanthelasma, since in extreme cases they can visually disfigure those affected.
A condition in which eyelid disease is more of a side effect is facial paralysis. In the case of facial paralysis, an inflammation of the facial nerve, the nerve supply to the eyelids is also affected. These no longer close. There is a risk that the cornea will dry out.
Hello and welcome to my Health Guide & Encyclopedia! My name is Dorothy Farrar, and I'm the founder and main author of this platform.
My passion for health and wellness started at a young age when I became interested in the connection between the food we eat and the way we feel. This fascination led me to study nutrition and dietetics in college, where I learned about the importance of a balanced diet and the impact of various nutrients on the body.