The organ of vision is one of the most important organs of man, because it is thanks to the eyes that we receive about 85% of the information from the outside world. A person does not see with his eyes, they only read visual information and transmit it to the brain, and there the picture is already formed. Eyes are a kind of visual intermediary between the outside world and the human brain.
The eyes are very vulnerable, the anatomy of the structure of the eyeball involves many different diseases that can be prevented, you only need to go a little deeper into the knowledge of anatomy.
Definition
The eye is a paired organ of the human visual system, which is susceptible to magnetic radiation in light terms provides the function of vision.
based on the anatomy of the human eyeball, it is located in the upper part of the face with components: eyelids, eyelashes, lacrimal system. Eyes are actively involved in facial expressions.
We consider in detail the anatomy of the eyeball, each of its components.
Eyelids
By eyelids, we mean skin folds above the eyeball, which are always mobile, due to this, blinking of the eyes occurs. This is possible due to the ligaments that are located on the edges of the eyelids. The eyelids have 2 ribs: anterior and posterior, between them an intermarginal area. The ducts of the meibomian glands are suitable here . According to the anatomy of the eyeball, these glands produce a secret that lubricates the eyelids so that they can glide.
On the front edge of the eyelid there are hair follicles, they provide the growth of eyelashes. The back rib functions so that both eyelids fit the eyeball tightly.
The eyelids are responsible for saturating the eye with blood and conduct nerve impulses, and also carry the function of protecting the eyeball from mechanical damage and other influences.
Eye socket
The orbit is called the bone cavity that protects the eyeball. Its structure includes four parts: external, internal, upper and lower. All these parts are reliably interconnected and form a solid whole. The most durable is the outer part, the inside is somewhat weaker.
The bone cavity is adjacent to the sinuses: inside - with the ethmoidal labyrinth, above - with the frontal void, below - with the maxillary sinus. This neighborhood is somewhat dangerous due to the fact that with tumor formations in the sinuses, they can also develop in the orbit itself. The opposite is also possible: the orbit is connected to the skull, so there is the possibility of the transition of the inflammatory process in the part of the brain.
Pupil
The pupil of the eyeball is part of the structure of the organ of vision, a recessed opening of a round shape, which is located in the very center of the iris of the eyeball. Its diameter is variable, this regulates the penetration of light particles into the inner part of the eye. The anatomy of the muscles of the eyeball is represented by the following muscles of the pupil: sphincter and dilator. Sphincters are responsible for ensuring the narrowing of the pupil, the dilator - for its expansion.
The size of the pupils is self-regulating, a person can not influence this process. But it is affected by an external factor - the level of illumination.
The pupil reflex is provided through the sensation and uplift of motor activity. First, a signal goes in response to some effect, then the work of the nervous system begins, which provokes a reaction to a specific stimulus.
Lighting helps to narrow the pupil, it separates the blinding light, which preserves vision throughout the life of a person. This reaction is characterized in two ways:
- direct reaction: one eye is exposed to light, it reacts properly;
- friendly reaction: the second eye does not light up, but responds to light that affects the first eye.
Optic nerve
Optic nerve function is the delivery of information to parts of the brain. The optic nerve follows the eyeball. The length of the optic nerve is not more than 5-6 cm. The nerve is immersed in the fat space, which protects it from damage. The nerve originates in the back of the eyeball, it is there that the accumulation of nerve processes is located, they give the form of a disk, which, going beyond the orbit, descends into the shell of the brain.
The processing of information received from the outside depends on the optic nerve, it is he who delivers information on the resulting visual picture to certain areas of the brain.
Cameras
In the structure of the eyeball there are enclosed spaces, they are called the eyeball cameras, they contain intraocular fluid. There are only two such cameras: the front and the back, they are interconnected, and the pupil is the connecting element for them.
The anterior chamber is the area beyond the cornea; the posterior chamber is behind the iris. The volume of the cameras is constant, it does not change under the influence of external factors. The functions of the cameras are in the relationship between different intraocular tissues, in the receipt of light signals on the retina.
Schlemm's channel
This is a passage inside the sclera, it is named after the German doctor Friedrich Schlemm. In the anatomy of the eyeball, he occupies an important place.
This channel is necessary in order to remove moisture with the provision of its absorption by the ciliary vein. The structure resembles a lymphatic vessel. With infectious processes in the Schlemm canal, a disease occurs - eye glaucoma.
Shell of the eye
- Fibrous membrane of the eye.
This is such a connective tissue that supports the physiological shape of the eye, is also a protective barrier. The structure of the fibrous membrane suggests the presence of two components: cornea and sclera.
- Cornea. Transparent and flexible shell, the shape resembles a convex-concave lens. The functionality is similar to a camera lens - focusing light rays. It includes five layers: endothelium, stroma, epithelium, Descemet's membrane, Bowman's membrane.
- Sclera. An opaque shell of the eyeball, which ensures the quality of vision due to the fact that it prevents the penetration of light rays through the shell of the sclera. The sclera serves as the basis for the elements of the eye that are located outside the eyeball (vessels, muscles, ligaments and nerves).
- Vascular membrane of the eye.
The anatomy of the structure of the eyeball suggests the layering of the choroid, it consists of three parts:
- Iris. The shape of the disk is in the center of which the pupil is located. It includes three layers: muscular pigment, borderline and stromal. Fibroblasts make up the boundary layer, then melanocytes containing color pigment are located. Eye color depends on the number of melanocytes. Next is the capillary network. The back of the iris is made up of muscles.
- Ciliary body. In this part of the choroid, ocular fluid is produced. The ciliary body consists of muscles and blood vessels. The activity of the layers of the ciliary body makes the lens work, as a result we get a clear image, being at different distances from the object in question. This part of the choroid also retains heat in the eyeball.
- Choroid The vascular part, which is located behind, is located between the dentate line and the optic nerve, consists mainly of the ciliary arteries of the eye.
Retina
The structure of the eyeball that regulates the amount of light is called the retina. This is the peripheral part of the eyeball, which is involved in starting the work of the visual analyzer. With the help of the retina, the eye picks up waves of light, converts them into impulses, and then they are transmitted to the brain through the optic nerve.
The retina is also called retina, it is the nervous tissue that forms the eyeball in the element of its inner shell. Retina is the bounding space in which the vitreous is located. The structure of the retina is complex and multi-layered, each layer is in close interaction with each other, damage to any of the layers of the retina has negative consequences. Consider each of the layers:
- Pigmented epithelium is a barrier to the emission of light so that the eye is not blinded. The functions are wide - protection, cell nutrition, transportation of nutrients.
- Photosensory layer - contains cells highly sensitive to light in the form of cones and rods. The sticks are responsible for the sense of color, and cones for vision in low light.
- Outer membrane - carries out the collection of light rays on the retina and their delivery to the receptors.
- Nuclear layer - consists of cell bodies and nuclei.
- Plexiform layer - characterized by cellular contacts that occur between cellular neurons.
- Nuclear layer - thanks to tissue cells it supports the important nerve functions of the retina.
- Plexiform layer - consists of plexuses of nerve cells in their processes, separates the vascular and non-vascular parts of the retina.
- Ganglion cells - are the conductors between the optic nerve and light-sensitive cells.
- Ganglion cell - forms the optic nerve.
- Boundary membrane - consists of Mueller cells and covers the retina from the inside.
Vitreous body
In the photo of the eyeball, you can see that the structure of the vitreous body resembles a gel-like substance, it fills the eyeball by 70%. It consists of 98% water, there is also a small amount of hyaluronic acid.
In the anterior zone there is a notch adjacent to the lens of the eye. The back zone is in contact with the membrane membrane of the retina.
The main functions of the vitreous body :
- gives the eye a physiological form;
- refracts rays of light;
- creates the necessary tension in the tissues of the eyeball;
- helps achieve incompressibility of the eyeball.
Lens
This is a biological lens, in shape it is biconvex, performing the function of conducting and refracting light. Thanks to the lens, the eye can focus on various objects located at different distances.
The lens is located in the posterior chamber of the eyeball, height is from 7 to 9 mm, thickness is about 5 mm. With age-related changes in the eye, the lens becomes thicker.
Inside the lens there is a substance that is held by a special capsule with the thinnest walls, consisting of epithelial cells. Epithelial cells are constantly dividing.
Functions of the lens of the eyeball:
- Light conduction is a crystalline lens, therefore it easily conducts light.
- Refraction of light rays - the lens is a biological lens of a person.
- Accommodation - the shape of a transparent body can change in order to clearly see objects at different distances.
- Separation - is involved in the formation of two bodies of the eye: the anterior and posterior, this allows you to keep the vitreous in place.
- Protection - the lens protects the eye from the penetration of pathogens, when they appear in the anterior chamber of the eye, they cannot go further.
Zinnova bunch
The ligament is formed of fibers that fix the lens in place, it is located just behind it. Zinnova ligament helps to contract the ciliary muscle, thanks to this the lens changes curvature, and the eye will focus on objects located at different distances.
The Zinnova ligament is the main element of the eye system, which ensures its accommodation.
Eyeball function
This is the ability of the eye to distinguish light from darkness. Three light sensing functions are distinguished here:
- Daytime vision: provided by cones, suggests good visual acuity, a wide palette of color perception, increased contrast of vision.
- Twilight vision: in low light, the activity of the rods can improve the quality of vision. It is characterized by high-quality peripheral vision, achromaticity, dark adaptations of the eye.
- Night vision: occurs due to sticks at certain limits of illumination, it comes down only to the sensations of light waves.
- Central (objective) vision.
The ability of the eyeball to distinguish objects by their shape and brightness, as well as recognize the details of objects. Central vision is provided by cones, measured by visual acuity.
Helps to navigate and move in space, provides twilight vision. It is measured by the field of view - during the study, the boundaries of the field are found and visual defects within these boundaries are detected, red, white and green colors are used for research.
It is characterized by the ability of the eye to distinguish colors from each other. Irritants: green, blue, violet and red. Color perception comes from the activity of cones. The study of color perception is carried out using spectral and polychromatic tables.
- Binocular vision is the process of seeing with two eyes.
Common eye diseases
- Angiopathy. Retinal vascular disease of the eyeball, which occurs when blood circulation is disturbed. Symptoms may include: blurred vision, "lightning" in the eyes. Most often, this disease is observed in people over 35 years old. After examining the fundus, the doctor makes a diagnosis.
- Astigmatism. This is an anomaly in the structure of the optical system of the eyeball, in which the rays of light undergo incorrect focusing on the retina. The lens or cornea can be disturbed, depending on this, corneal or lens astigmatism is secreted. Symptoms are manifested in visual impairment, image bifurcation, blurry objects.
- Myopia. This violation of the function of the eyeball is due to the fact that the optical eye system is distorted when the focus of the image is concentrated not on the retina, but on its front region. Because of this, a person sees objects in the distance vaguely and vaguely, this does not apply to nearby objects. The degree of pathology is determined by the clarity of distant images.
- Glaucoma. An anomaly of a chronic nature of the disease, glaucoma leads to irreversible changes in the optic nerve due to periodic or constant increase in intraocular pressure. It proceeds either without symptoms, or with slight deviations in vision. If a person does not receive proper treatment for glaucoma, then ultimately this leads to blindness.
- Farsightedness. Pathology of the eyeball, characterized by focusing the image behind the retina. With slight deviations, vision remains normal, with moderate changes, focusing of vision is difficult for close objects, with severe pathology, a person does not see well both close and far. Hyperopia is accompanied by headaches, strabismus and rapid visual fatigue.
- Diplopia. Visual apparatus dysfunction, in which the image is seen with a doubling due to the fact that the eyeball is deviated from its normal position. Such a pathology of vision occurs due to damage to the muscle fibers of the eyeball. Variations of doubling can be as follows: a person sees a parallel doubling of the image; a person sees a doubling of the image above each other. In diplopia, patients complain of frequent aching headaches.
- Cataract. It occurs due to the slow process of replacing water-soluble proteins with water-insoluble proteins in the lens, this is accompanied by swelling and inflammation of the lens, and the transparent body begins to cloud. The anomaly is dangerous because the process is irreversible, and the course of the disease passes rapidly and quickly.
- Cyst. This benign neoplasm can be congenital or acquired. At the beginning of the disease, small vesicles form with inflamed skin around them, then they grow rapidly and require medical intervention. The process is accompanied by a weakening of vision, pain during blinking of the eyelids. The reasons can be different: from heredity to acquired inflammation.
- Conjunctivitis. This is inflammation in the conjunctiva of the eye - the transparent membrane of the eyeball. It can be viral, allergic, fungal or bacterial. Some types of conjunctivitis are highly contagious and can be transmitted through household hygiene products, and infection from animals is also possible. Symptoms of the disease are purulent compartments from the eyes, eyeball swelling, hyperemia, burning and itching of the eyelids.
- Retinal detachment. This pathology is characterized by the separation of the layers of the retina of the eyeball from the pigment epithelium and choroid. An extremely dangerous disease, in the presence of which you can not do without surgical intervention. , . , , .
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In cases of damage to the eyeball with an infection or fungus, antibiotic-based drugs are usually prescribed, these can be eye drops, tablets, ointments that are placed under the lower eyelid, as well as intramuscular injections. Such drugs kill germs and prevent the further development of the disease.
If the violation of visual function is associated with functional damage to the eyeball, then glasses are prescribed as a treatment, for example, this is widely practiced with astigmatism, myopia, hyperopia.
When visual impairment is accompanied by pain in the eyes and headaches, surgical intervention of an eye surgeon can be prescribed, for example, with eye glaucoma. Currently, the laser method is increasingly used for eye surgery, it is the least painful and very fast. Such an operation allows you to solve the problem of eye disease in just a few minutes, there are practically no complications. Used for myopia, astigmatism and cataracts.
With eye strain and periodic pain, you can use supportive methods: take vitamin complexes to improve vision, eat foods that improve vision (blueberries, seafood, carrots and others).
We examined the anatomy of the human eyeball. Proper nutrition, a clear daily routine, an 8-hour sleep - all this can be an excellent prevention of eye diseases. Eating fresh fruits, an active lifestyle and a limited pastime at computers play a big role in high-quality vision for many years!