Also called sclera. Sclera of the eye: structure, functions, diseases and treatment

The sclera is the largest outer layer of the eyeball. It covers 5/6 of its entire surface. The range of thicknesses in different areas of a given shell can vary from 0.3 to 1 mm.

What is the sclera of the eye?

Sclera– fibrous opaque membrane of the eyeball. It is the density and opacity of the sclera that ensures high-quality vision and maintenance of intraocular pressure. It protects the inner eye from damage and acts as a support for external tissues: muscles, blood vessels, nerves.

Structure

The sclera has several layers. The outer layer, or episcleral, as it is also called, is penetrated by a mass of blood vessels that provide its high-quality blood supply, and is also securely connected to the outer surface of the eye capsule.

Due to the fact that the main part of the blood vessels passes through the anterior part of the eye, the upper part of the episcleral layer has a more intense blood supply than the internal parts.

The second layer, or the sclera itself, directly consists of collagen and fibrocytes, which participate in the process of producing collagen itself and separate its fibers.

The very last inner layer of the sclera, or the so-called brown plate, got its name for its rich pigment content, which determines the specific color of this layer of the eye shell.

Special cells - chromatophores, which are contained in large quantities in this layer, are responsible for the pigmentation of such a plate. Basically, the brown plate consists of thinner scleral fibers with some admixture of an elastic component, and the outside is covered with a special layer - endothelium.

The entire thickness of the sclera is penetrated by blood vessels and nerve endings passing through special channels - emissaries.

Functions

The first function of the sclera is due to the fact that the collagen fibers filling it do not have a strictly defined location. Therefore, light rays cannot penetrate the scleral tissue.

Thanks to this function, high-quality vision of the human eye is ensured, since the sclera protects from too intense external light. But the most important is the second function of this shell - protective.

This is its main purpose, to protect the eyeball from all types of damage, both mechanical and physical, as well as negative environmental influences.

It is also worth noting another important function of this shell; it can conditionally be called a frame shell. After all, it is the sclera of the eye that serves as a support and attachment element for many muscles, ligaments and other components of the human eye.

Diseases

Since the sclera performs very important and diverse functions that affect the functioning of the entire visual apparatus as a whole, diseases of this part of the eye can contribute to a rapid decrease in visual acuity. Diseases of such a membrane can be caused by various reasons and can be either congenital or acquired.

For example, the development of blue sclera syndrome in a person can be genetic and caused by improper formation of the connective tissue of the eyeball in the womb. The unusual color of the sclera in such a person is explained by its too small thickness, through which the pigment of the next eye membrane shines through. Moreover, such a syndrome may well be accompanied by other anomalies of the elements of the eye, as well as a disorder in the formation of joints, bone tissue or hearing organs.

Another congenital anomaly that is worth noting is melanosis. The sclera of the eye with the development of melanosis has characteristic dark spots on its surface. Such patients must be registered with a qualified ophthalmologist for constant monitoring and timely prevention of possible complications.

Of the acquired diseases of the outer eye membrane, inflammatory diseases deserve special attention. Their development can be provoked by both general disturbances in the functioning of any system of the human body and infections. This fact is due to the fact that pathogenic microbes from other organs with the flow of blood or lymph can enter the scleral tissue and provoke their inflammation.

Treatment

Treatment of diseases of the sclera, like any other organ of the human body, begins with a high-quality diagnosis and consultation with a doctor who, depending on the symptoms and test results, will be able to make the correct diagnosis and prescribe effective treatment.

Moreover, if the visual disorder is caused by another disease, then it is necessary to eliminate the root cause, and only then restore vision. As a rule, for the effective treatment of inflammatory processes, such as the sclera of the eyeball, physiotherapeutic, medicinal and surgical treatment methods are used.

Remember, vision is so valuable that it does not tolerate indifferent treatment, and it is on timely access to a doctor that in many cases the ability to preserve it depends.

This is the first function of the sclera - providing high-quality vision, due to the fact that light rays cannot penetrate the scleral tissue, which would cause blinding. The main functions of the sclera are the protection of the inner membranes of the eye from external damage and support for the structures and tissues of the eye located outside the eyeball: extraocular muscles, ligaments, blood vessels, nerves. Being a dense structure, the sclera, in addition, is involved in maintaining intraocular pressure and, in particular, the outflow of aqueous humor, due to the presence of the Shlemov canal.

The structure of the sclera

The sclera consists of several layers: the episclera, that is, the outer layer, the sclera itself and the inner layer - the so-called brown plate.
The episcleral layer has a very good blood supply and is also connected to the outer fairly dense Tenon's capsule of the eye. The anterior sections of the episclera are richest in blood flow, since blood vessels pass to the anterior section of the eyeball in the thickness of the rectus extraocular muscles.
The scleral tissue consists of dense collagen fibers; between them there are cells, so-called fibrocytes, which produce collagen.
The inner layer of the sclera is externally described as a brown plate, as it contains a large number of pigment-containing cells - chromatophores.
Several end-to-end channels, the so-called emissaries, pass through the thickness of the sclera, which are a kind of conductors for blood vessels and nerves entering or exiting the eyeball. At the anterior edge, on the inner side of the sclera, there is a circular groove, up to 0.8 mm wide. Its posterior protruding edge, the scleral spur, serves as the attachment point for the ciliary body. The anterior edge of the groove is in contact with the Descemet's membrane of the cornea. Most of the groove is occupied by the trabecular diaphragm, and at the bottom is Schlemm's canal.
Due to its connective tissue structure, the sclera is susceptible to the development of pathological processes that occur in systemic connective tissue diseases or collagenoses.

Methods for diagnosing scleral diseases

• Visual inspection.
• Biomicroscopy is a study under a microscope.
• Ultrasound diagnostics.

Symptoms for diseases of the sclera

• Melanosis of the sclera.
• Congenital disorders of collagen structure, for example, in Van der Hewe's disease.

• Staphylomas of the sclera.
• Excavation of the optic nerve head is observed in glaucoma.
• Episcleritis and scleritis are inflammations of the scleral tissue.
• Scleral ruptures.

The human eye is a complex natural optical device through which 90 percent of the information for the brain comes. The sclera is a functional element.

The condition of the shell indicates eye diseases and other pathologies of the body. In order to recognize the disease in time, you should understand what sclera is.

Shell structure

The sclera is the outer tunica albuginea made of dense connective tissue that protects and holds the internal functional elements.

The white of the eye consists of bundle-shaped, randomly arranged collagen fibers. This explains the opacity and different densities of the fabric. The thickness of the shell ranges from 0.3 to 1 mm; it is a capsule of fibrous tissue of unequal thickness.

The white of the eye has a complex structure.

1. The outer layer is a loose tissue with a branched vascular system, which is divided into deep and superficial vascular networks.
2. The sclera itself, consists of collagen fibers and elastic tissues.
3. The deep layer (brown plate) is located between the outer layer and the choroid. Consists of connective tissue and pigment cells - chromatophores.

The posterior part of the eye capsule has the appearance of a thin plate with a lattice structure.

Functions of the scleral membrane

The fibers of the cover are arranged chaotically, protecting the eye from the penetration of sunlight, which ensures effective vision.

The scleral region performs important physiological functions.

1. The eye muscles, which are responsible for eye mobility, are attached to the tissues of the capsule.
2. The ethmoidal arteries of the posterior part penetrate the sclera.
3. A branch of the ophthalmic nerve approaches the eyeball through the capsule.
4. The capsule tissue serves as the shell.
5. Whirlpool veins emerge from the eye through the protein body, which provide the outflow of venous blood.

The tunica albuginea, due to its dense and elastic structure, protects the eyeball from mechanical injuries and negative environmental factors. Protein serves as a framework for the muscular system and ligaments of the organ of vision.

What should the sclera of a healthy person look like?

The sclera is normally white with a bluish tint.

Due to their small thickness, the child has blue sclera, through which the pigment and vascular layer are visible.

A change in color (dullness, yellowness) indicates disturbances in the body. The presence of yellowish areas on the surface of the white indicates eye infections. A yellow tint may be a symptom of liver disorders, hepatitis. In infants, the covering is thinner and more elastic than in adults. Slightly blue sclera is normal at this age. In older people, the cover thickens, becomes yellow due to the deposition of fat cells, and becomes loose.

Blue sclera syndrome in humans is caused genetically or by a violation of the formation of the eyeball in the prenatal period.

Changing the type of protein is a justified reason for visiting a doctor. The condition of the integument affects the functioning of the visual system. Diseases of the sclera are divided into congenital and acquired.

Congenital pathologies

Melanosis (melanopathy)- a congenital disease that is expressed by pigmentation of the skin with melanin. Changes appear in the first year of life. The baby's whites have a yellowish tint, and pigmentation appears in the form of spots or stripes. The color of the spots may be gray or light purple. The cause of the anomaly is a violation of carbohydrate metabolism.

Blue sclera syndrome often accompanied by other eye defects, anomalies of the musculoskeletal system, and hearing aid. The deviation is congenital. Blue sclera may indicate iron deficiency in the blood.

Acquired diseases

Staphyloma is an acquired disease. It manifests itself as thinning of the membrane, protrusion. It is a consequence of eye diseases associated with destructive processes.

Episcleritis is an inflammation of the surface of the integument, accompanied by nodular seals around the cornea. It often goes away without treatment and may recur.

Scleritis is an inflammatory process affecting the inner layers of the scleral body, accompanied by pain. A rupture of the eye capsule may form at the site. The disease is accompanied by immunodeficiency and tissue swelling.

Necrotizing scleritis- develops as a consequence of long-term rheumatoid arthritis. It manifests itself as thinning of the membrane and the formation of staphyloma.

Diseases of inflammatory origin can occur as a result of infections and disruptions in the functioning of organs of the human body.

Timely contact with a doctor helps to promptly identify diseases of the sclera, establish the cause and begin treatment.

The sclera of the eye is the opaque outer layer of the eye. The sclera occupies the largest area of ​​the eye and has a dense composition. The sclera of the eye has different densities in different areas.

The thickness of the sclera also varies and ranges from 0.3 to 1 mm; in children it is very thin and increases over time.

Describing the structure of the sclera of the eye, three layers are distinguished. This is the outer layer, that is, the episclera, the sclera itself and the brown plate or inner layer.

The structure of the sclera of the eye

Outer layer (Episclera)– well supplied with blood, the vascular network is divided into superficial and deep. The best blood supply occurs in the anterior sections, because the vessels approach the anterior section of the eye, located in the thickness of the rectus extraocular muscles.

The sclera itself- just like it consists of collagen fibers, the space between which is occupied by fibrocytes - producing collagen.

Inner layer or brown plate– consists of thinned scleral fibers and elastic tissue. Fibers contain pigment-containing cells on their surface - chromatophores. These cells give the inner surface of the sclera a brown tint.

The thickness of the sclera contains several through channels that play the role of conductors for blood vessels and nerves, both entering and exiting the eye. The anterior edge of the inner side of the sclera has a so-called groove measuring 0.8 mm. The ciliary body is attached to the posterior edge of the groove, and its anterior edge is adjacent to Descemet's membrane. The main part of the groove is occupied by the trabecular diaphragm, above which is Schlemm's canal.

Due to the fact that the sclera of the eye is a connective tissue, it is susceptible to the development of pathological processes that occur in systemic connective tissue diseases or collagenoses.

In those places where the sclera is thinned, protrusions (formations) may occur - the so-called staphyls. In addition, there may be excavation (deepening), which is observed with glaucoma. Ruptures of the sclera also occur in its thin part, most often this occurs between the areas of attachment of the extraocular muscles.

Functions of the sclera

Protective;
- Support.

The main function of the sclera, of course, is protective - it protects the membranes of the eye located inside from various external damage. Also, the sclera does not allow light rays to pass through, which would lead to blinding; due to this, high-quality vision is achieved.

The sclera is a support for the tissues of the eye and its internal and external structures, which are located outside the eye - these are vessels, nerves, ligaments, etc.

In addition, the sclera of the eye takes part in the maintenance, namely, in the outflow through the Schlemm canal.

The opaque part of the fibrous membrane is the sclera of the eye. It covers 85% of all surfaces and is primarily responsible for transmitting visual information to the brain. Its structural features provide a wide range of functions. With anomalies and the development of pathologies, there is a risk of vision loss. Problems with the sclera cause a number of characteristic symptoms; if they exist, you should consult a doctor. Treatment depends on the current disease and the stage of its development; in most cases, local drug treatment is used.

Anatomy of the sclera

The sclera is the white membrane of the eye, located on the outside and, together with the cornea, is a fibrous tissue. Reaching the iris, it forms a dense protective ring. According to its physical characteristics, it has a white color and an opaque structure, due to which a person has vision. This is a fairly dense tissue of several layers; normally the thickness of the sclera reaches up to 1 mm. Despite this structure, the protein membrane of the eyeball can stretch, but this property decreases with age.

Shell structure

Density is ensured due to anatomical features. The structure of the sclera is a very complex process. The main component is collagen, it is arranged in a chaotic manner, thus causing the opacity of the eye. Full functionality is possible thanks to the multilayered shell, with the layers of the sclera differing in composition and density:

The shell has a very complex and intricate structure.

• Outer layer. The thinnest ball, filled with a large number of blood vessels.
• Middle layer. It is also called scleral and contains the maximum amount of collagen.
• Inner layer. It is a connective tissue in combination with the pigment part.

The visible part of the sclera is only the top layer, the subsequent ones are located inside, but when depleted, protrusion is possible. This process is observed in ophthalmic pathologies.

What functions does it perform?

The versatility of the shell is ensured by its complex structure. Each of the 3 layers plays its role and only a holistic effect guarantees full vision. All functions of the white membrane of the eye are quite diverse. First of all, we are talking about protecting the pupil from external damage. The sun has a negative effect on the condition of the eye. It is due to the refraction of light in the shell that the pupil does not dazzle and an image appears. In addition, the sclera performs the following functions:

• Untangles with fastenings for the vascular and muscular apparatus.
• Provides blood outflow through venous branches.
• Responsible for eye mobility.
• Conducts moisture through the venous sinus of the sclera.
• Provides safe passage of the nerve to the eyeball.

What does healthy sclera look like?

You can distinguish a diseased state of the protein sphere from a healthy one by color. In infancy, the sclera is thin, so the membranes appear blue. This condition is not considered pathological and goes away on its own over time. What color of proteins in an adult may indicate the genetic nature of the problem; dystrophic changes have formed at the intrauterine level.

Yellowness of the sclera indicates possible pathologies. At the same time, the shell looks dull and cloudy. Such changes may indicate the impact of an infection. Lesions are not only local; kidney disease affects the color of the proteins. In old age, there may be large quantities of fat cells in the eyes; they can change color to yellow.

Diseases

Pathologies that develop in the eyes at the level of the sclera are most often of an inflammatory nature, provoked by infections. However, primary sources are not always located directly in the organ. Painful manifestations in the membrane of the eye can only act as symptoms of the main processes. First of all, the ophthalmologist looks for the main diseases of the sclera, these include the following:

• Scleritis. An inflammatory pathology in which the inner layers of the membrane are affected.
• Staphyloma. The disease is caused by destructive processes, as a result of which the membrane is depleted.
• Episcleritis. Damage to the upper layer, accompanied by the formation of nodules.

Developmental anomalies

Congenital pathological forms pose a significant danger; they are difficult to diagnose and do not always respond to conservative treatment. These include blue sclera syndrome. This color may indicate insufficient iron in the blood. Often such a disease is not a single developmental deviation; other pathologies of the eyes, ears, and musculoskeletal system are also observed.

Another congenital pathology is melanosis or melanopathy. This disease is also associated with pigmentation, only the membrane becomes yellow due to saturation with melanin. This process occurs as a result of a violation of carbohydrate metabolism. Changes in color may appear in different ways, with distinctive layers or spots appearing on the top layer.