Structure, functions of the cornea of the eye

One of the most important organs of a person is the eyes. Thanks to them we get information about the outside world. The structure of the eyeball is quite complicated. This body has its own characteristics. We will talk further about which ones. Also, we will dwell in more detail on the structure of the eye as a whole and one of its components - the cornea - in particular. We shall discuss what the role of the cornea in the work of the organ of vision is and whether there is a relationship between its structure and the functions that the elements of the eye perform.

The human body of vision

Man with the help of the eyes has the opportunity to receive a large amount of information. Those who for some reason lost sight, it is very difficult. Life loses its colors, a person can no longer contemplate the beautiful.

In addition, the implementation of daily business is also difficult. Man becomes limited, he can not fully live. Therefore, people who have lost their eyesight are entitled to a disability group.

Functions of the eye

The eyes perform the following functions:

• Distinction of brightness and color of objects, their shape and size.
• Observation of the movement of objects.
• Determination of the distance to objects.

Thus, the eyes, along with other human organs, help him to live fully, without experiencing the need for outside help. If vision is lost, a person becomes helpless.

The eye 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 component parts of the eye, whose work is coordinated and coordinated.

Light rays are reflected from objects, and then touch the cornea of the eye, which is an optical lens. As a result, the rays are collected in one point. After all, the basic functions of the cornea are refractive and protective.

Then the light gets through the iris to the pupil of the eye and then to the retina. The result is a finished image in an inverted position.

Structure of the eye

The human eye consists of four parts:

• Peripheral, or perceiving part, which includes the eyeball, eye devices.
• Conductive paths.
• Subcortical centers.
• Higher visual centers.

The oculomotor muscles are subdivided into oblique and straight muscles of the eye, in addition, there is also a circular and such that lifts the eyelid. The functions of the oculomotor muscles are obvious:

• Rotation of the eyes.
• Raising and lowering the upper eyelid.
• Clenching the eyelids.

If all eye devices work correctly, then the eye functions normally - it is protected from damage and harmful environmental effects. This helps a person visually perceive reality and live a full life.

Eyeball

The eyeball is a globular body located in the orbit. The eyes are located on the face of the skeleton, their main function is to protect the eyeball from external influences.

The eyeball has three membranes: the outer, the middle and the inner.

The first one is called fibrous. It has two departments:

• The cornea is a transparent anterior section. The functions of the cornea are extremely important.
• Sclera - opaque posterior section.

The sclera and the cornea are elastic, thanks to them the eye has a definite shape.

The sclera has a thickness of about 1.1 mm, it is covered by a thin transparent mucous membrane - conjunctiva.

Cornea of the eye

The cornea is called the transparent part of the outer shell. Limb - this is the place where the iris goes to the sclera. The thickness of the cornea is 0.9 mm. The cornea is transparent, its structure is unique. This is explained by the arrangement of cells in a strict optical order, and even in the cornea there are no blood vessels.

The shape of the cornea resembles a convex-concave lens. Often it is compared with a glass for a clock with an opaque frame. The sensitivity of the cornea of the eye is caused by a large number of nerve endings. It has the ability to transmit and refract light rays. Its refractive power is enormous.

When the child turns ten years old, the corneal parameters are equated to the parameters of the adult person. 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 are salts and lipids.

What is the function of the cornea? About this - further.

The structure of the cornea and its functions

The cornea has five layers, each has its own functionality. The layers are as follows:

• stroma;
• Epithelium, which is subdivided into anterior and posterior;
• Bowman's membrane;
• Descemet's membrane;
• endothelium.

Next, consider the correspondence of the structure and function of the cornea.

The stroma layer is the thickest. Filled with its finest plates, the fibers of which are collagen. The arrangement of the plates is parallel to the cornea and to each other, but the direction of the fibers in each plate is different. Due to this, a strong cornea of the eye fulfills the function - protects the eye from damage. If you try to pierce the cornea with a scalpel that is not sharpened, then it will be quite difficult to do this.

The epithelial layer has the ability to self-repair. His cells are regenerated, and even the scar does not remain in place of the damage. And there is a recovery 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.

On the stroma there is a special layer - Bowman's shell, which has no cells, and if it is damaged, the scars will necessarily remain.

The Descemet's membrane is located next to the endothelium. It also consists of collagen fibers, prevents the spread of pathogenic microorganisms.

Endothelium - 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 layer of the endothelium.

The triple nerve provides innervation of the cornea. The vascular network, the nerves, the moisture of the anterior chamber, the tear film - all this ensures its nutrition.

Functions of the human cornea

• The cornea is strong and highly sensitive, so it performs a protective function - protects the eyes from damage.
• The cornea is transparent and has a convex-concave shape, so it spends and refracts the light.
• Epithelium is a protective layer, due to which the cornea performs a function similar to that of the protective one - it prevents the infection from getting inside. Such a nuisance can occur only with mechanical damage. But even after that, the anterior epithelium will quickly recover (within 24 hours).

Harmful effects on the cornea

Eyes are regularly exposed to the following harmful effects:

• Contact with mechanical particles that are suspended in the air;
• Chemical substances;
• The movement of air;
• Temperature differences.

When foreign particles get into the eye, the unconscious reflex closes the eyelids, tears flow strongly and a reaction to light is observed. Tears help to wash 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 shell does not occur.

The same protective reaction is also observed with chemical action, with strong wind, bright sun, cold and heat.

Diseases of the organs of vision

There is a large number of eye diseases. We list some of them:

• Presbyopia is an age-related form of hyperopia, in which the elasticity of the lens is lost, and the zinn ligaments that hold it are weakened. It is clear to see a person can only objects that are at a distant distance. This deviation from the norm manifests itself with age.
• Astigmatism is a disease in which light rays are unequally refracted in different directions.
• Myopia (myopia) - the rays intersect before the reticular membrane.
• Hyperopia (hypermetropia) - the rays intersect beyond the mesh membrane.
• Protanopia, or color blindness - in this disease, a person almost does not have the opportunity to see all the shades of red.
• Deuteranopia - the green color and all its shades are not perceived. Anomaly is congenital.
• Tritanopia - with this violation of the refraction of the eye, a person does not have the opportunity to see all the shades of blue.

If there are any violations in the work of the eye, you need to contact an ophthalmologist. The doctor will perform all the necessary tests and on the basis of the results obtained will diagnose. Then you can start treatment. As a rule, most diseases associated with the violation of the eyeball, can be corrected. An exception is only congenital anomalies.

Science does not stand still, so now the functions of the human cornea can be restored surgically. The operation passes quickly and painlessly, but thanks to this it is possible to get rid of the forced need to go with glasses.