One of the most important human organs is the eyes. Thanks to them, we get information about the outside world. The structure of the eyeball is quite complex. This body has its own characteristics. We will talk about which ones later. We also dwell in more detail on the structure of the eye as a whole and one of its components - the cornea - in particular. Let us discuss the role of the cornea in the functioning of the organ of vision and whether there is a relationship between its structure and the functions performed by this element of the eye.
Human organ of vision
A person with the help of eyes has the ability to receive a large amount of information. Those who, for whatever reason, lost their sight, have a very hard time. Life loses its color, a person can no longer contemplate the beautiful.
In addition, the execution of daily activities also becomes difficult. A person becomes limited; he cannot fully live. Therefore, people who have lost their eyesight are assigned a disability group.
Eye function
The eye performs the following functions:
- Distinguishing the brightness and color of objects, their shape and size.
- Observation of the movement of objects.
- Determining the distance to objects.
Thus, the eyes, along with other organs of a person, helps him to live fully, without experiencing the need for outside help. If vision is lost, a person becomes helpless.
The ocular apparatus is an optical system that helps a person perceive the world around him, process information with high accuracy, and transmit it. A similar goal is fulfilled by all the constituent parts of the eye whose work is coordinated and coordinated.
Light rays are reflected from objects, after which they touch the cornea of the eye, which is an optical lens. As a result, the rays are collected at one point. After all, the main functions of the cornea are refractive and protective.
Then the light passes through the iris to the pupil of the eye and further to the retina. The result is a finished picture in an inverted position.
Eye structure
The human eye consists of four parts:
- The peripheral, or receptive part, which includes the eyeball, the apparatus of the eye.
- Conductive paths.
- Subcortical centers.
- Higher visual centers.
The oculomotor muscles are divided into oblique and rectus muscles of the eye, in addition, there is also a circular and one that raises the eyelid. The functions of the oculomotor muscles are obvious:
- The rotation of the eyes.
- Raising and lowering the upper eyelid.
- Squinting eyelids.
If all eye devices work correctly, then the eye functions normally - it is protected from damage and the harmful effects of the environment. This helps a person to visually perceive reality and live a full life.
Eyeball
An eyeball is a spherical body located in the orbit. The eye sockets are located on the front surface of the skeleton, their main function is to protect the eyeball from external influences.
The eyeball has three shells: the outer, middle and inner.
The first is also called fibrous. It has two departments:
- The cornea is a transparent anterior section. The functions of the cornea are extremely important.
- The sclera is an opaque back.
The sclera and cornea are elastic, thanks to them the eye has a certain shape.
The sclera has a thickness of about 1.1 mm, it is covered by a thin transparent mucous membrane - the conjunctiva.
Cornea
The cornea is called the transparent part of the outer shell. The limb is where the iris goes into the sclera. The cornea is 0.9 mm thick. The cornea is transparent, its structure is unique. This is explained by the arrangement of cells in a strict optical order, and there are no blood vessels in the cornea.
The shape of the cornea resembles a convex-concave lens. Often it is compared with glass for watches with an opaque frame. The sensitivity of the cornea due to the large number of nerve endings. It has the ability to transmit and refract light rays. The refractive power of her is huge.
When a child turns ten years old, the parameters of the cornea are equated with the parameters of an adult. These include shape, size and optical power. But when a person becomes elderly, an opaque arc is formed on the cornea, which is called senile. The reason for this is salts and lipids.
What function does the cornea perform? About it - further.
The structure of the cornea and its functions
The cornea has five layers, each with its own functionality. The layers are as follows:
- stroma;
- epithelium, which is divided into anterior and posterior;
- Bowman's membrane;
- Descemet's membrane;
- endothelium.
Next, we consider what is the correspondence of the structure and function of the cornea.
The stroma layer is the thickest. The thinnest plates are filled with collagen fibers. The arrangement of the plates is parallel with respect to the cornea and each other, but the direction of the fibers in each plate is different. Due to this, the strong cornea of the eye performs the function of protecting the eye from damage. If you try to pierce the cornea with a scalpel, which is poorly sharpened, then it will be quite difficult to do this.
The epithelial layer has the ability to self-repair. Its cells regenerate, and even a scar does not remain at the site of damage. Moreover, recovery occurs very quickly - in one day. The anterior and posterior epithelium is responsible for the fluid content in the stroma. If the integrity of the anterior and posterior epithelium is impaired, the cornea may lose its transparency due to hydration.
There is a special layer on the stroma - the Bowman shell, which has no cells, and if it is damaged, the scars will remain.
Descemet's membrane is located next to the endothelium. It also consists of collagen fibers, prevents the spread of pathogenic microorganisms.
The endothelium is a single cell layer, nourishes and supports the cornea, does not allow it to swell. It is not a regenerating layer. The older the person, the thinner the endothelium layer.
The trigeminal nerve provides innervation of the cornea. The vascular network, nerves, moisture of the anterior chamber, and the tear film - all this provides its nutrition.
Functions of the cornea of the human eye
- The cornea is strong and highly sensitive, therefore it performs a protective function - it protects the eyes from damage.
- The cornea is transparent and has a convex-concave shape, so it conducts and refracts light.
- The epithelium is a protective layer, thanks to which the cornea performs a function similar to the protective one - it prevents infection from getting inside. Such a nuisance can occur only with mechanical damage. But even after this, the anterior epithelium will quickly recover (within 24 hours).
Harmful factors affecting the cornea
Eyes are regularly exposed to the following harmful effects:
- contact with mechanical particles that are suspended in the air;
- chemicals
- air movement;
- temperature differences.
When foreign particles get into the eye of a person, the eyelids close by an unconditioned reflex, tears flow intensely and a reaction to light is observed. Tears help flush out foreign agents from the surface of the eye. As a result, the protective functions of the cornea are fully manifested. Serious damage to the membrane does not occur.
The same protective reaction is also observed with chemical exposure, with strong winds, bright suns, in cold and heat.
Visual diseases
There are many eye diseases. We list some of them:
- Presbyopia is a senile form of farsightedness, in which the elasticity of the lens is lost, and the zinc ligaments that hold it weaken. A person can see clearly only objects that are far away. This deviation from the norm manifests itself with age.
- Astigmatism is a disease in which light rays are not equally refracted in different directions.
- Myopia (myopia) - rays intersect in front of the retina.
- Hyperopia (hyperopia) - rays intersect behind the retina.
- Protanopia, or color blindness - with this disease, a person has almost no opportunity to see all shades of red.
- Deuteranopia - green color and all its shades are not perceived. An anomaly is congenital.
- Tritanopia - with this violation of eye refraction , a person does not have the opportunity to see all shades of blue.
If any disturbances in the work of the organs of vision occur, you need to contact a specialist - an ophthalmologist. The doctor will conduct all necessary tests and, based on the results, make a diagnosis. Then you can start treatment. As a rule, most diseases associated with disruption of the eyeball can be corrected. The exception is only congenital anomalies.
Science does not stand still, so now the functions of the cornea of the human eye can be restored surgically. The operation is quick and painless, but thanks to this you can get rid of the forced need to wear glasses.