Let's get acquainted with the structure and functions of the sclera. Scleritis is a serious and dangerous eye disease. The albumen of the eye.

Hello, dear readers!

I present to your attention another article from the “Structure of the Eye” section.

Today we will talk about the sclera - the main part of the fibrous membrane of the eyeball. This also includes the cornea, but we will talk about it in the next article.

Visually, we see the sclera as a white dense layer of the front surface of our eye, but in fact it covers 5/6 of the area of the eyeball.

In my article I want to talk about the structural features of the sclera and the important functions that it performs.

What is the sclera

The outer fibrous membrane of the eye is represented by the sclera, which borders the cornea in front.

But unlike the transparent cornea, the sclera is an opaque shell with a dense composition that resembles tendon in appearance.

The sclera is normally white, which is why we usually call its visible part the “white of the eye.”

In newborns it may have a blue tint, and in older people it may have a yellowish tint.

On top, the sclera (tunica albuginea) is covered with a transparent layer - the conjunctiva.

Structure of the tunica albuginea

The thickness and density of the sclera in different areas is different and varies from 0.3 to 1.0 mm.

The greatest thickness - at the base of the optic nerve - is up to 1.2 mm. In front, the shell becomes thinner, and at the border of the connection with the cornea it does not exceed 0.3-0.4 mm.

In the center of the posterior part, the sclera is a multilayer cribriform plate through which the optic nerve and retinal vessels pass.

The structure of the sclera consists of three layers:

episclera - is a superficial and loose layer. It is penetrated by blood vessels and is characterized by excellent blood supply;
the sclera itself - it consists of collagen fibers and is similar in structure to the cornea. In the space between the fibers there are fibrocides responsible for the production of collagen.
Collagen fibers are arranged in a chaotic sequence, which explains the opacity of the tunica albuginea.
brown plate (inner layer) - got its name because of the large number of pigment-containing cells - chromatophores, which give this layer its brown color.

Blood supply

The vascular supply system of the sclera is divided into deep and superficial.

The anterior (outer) sections are rich in excellent blood flow. This is explained by the fact that the blood vessels, passing through the entire thickness of the oculomotor muscles, exit directly to the anterior part of the eye.

Blood vessels pass through the thickness of the sclera through emissaries - special openings that are through channels.

The shell also contains its own vessels, but in minimal quantities. The sclera is mainly supplied by transit conjunctival vessels.

Structural features

Since the structure of the sclera is connective tissue, this membrane is susceptible to the occurrence of various pathological processes.

Thin sclera is observed in children; with age it acquires the required thickness.

As the body ages, the fibrous membrane becomes thinner, which is associated with a loss of elasticity and stretchability, as well as an increase in its water content.

In places where it becomes thinner, protrusions or tears may appear.

Such vulnerable areas are the attachment points of the tendons of the eye muscles, where the thickness of the sclera is minimal. Therefore, most often in case of eye injuries, ruptures occur here.

The sclera has practically no nerve endings, as a result of which it is insensitive when exposed.

Purpose of the sclera

To ensure the functionality of the ocular apparatus, the fibrous membrane performs a number of important functions:

Protective
Of all the functions performed by the sclera, the main one is considered protective. Its purpose is to protect all other membranes of the eye from mechanical influences (for example, shocks) or adverse external factors.
Frame
The sclera supports all the internal structures of the eye and its external components, which are located outside the ocular apparatus.
Thanks to the sclera, the constant spherical shape of the eye is maintained; vessels, ligaments, nerves, as well as six external muscles that are responsible for the direction of gaze and ensure synchronous rotation of the two eyes in different directions are attached to it.
Optical
Since the sclera is an opaque tissue, its function is to protect the retina from excessive light, in particular from the appearance of so-called side lights and glare, which provides a person with good vision.
Stabilization
The sclera is directly involved in maintaining intraocular pressure. This ensures the normal functioning of all structures of the ocular apparatus.

Pressure causes tension on the collagen fibers that make up the sclera. Gradually stretching and therefore becoming thinner, the sclera ceases to perform its functions efficiently.

On the inside of the anterior edge, a circular groove runs along the sclera, at the bottom of which there is an oval-shaped vessel - Shlemov Canal (Shlema), also called scleral venous sinus. This channel exists to drain intraocular fluid and maintain its optimal circulation.

These are the structural features and main functions of the white membrane of the eye. In one of the following articles we will talk about diseases of the sclera and their treatment.
Be healthy!

The sclera is the outer layer of the eye, which is formed by numerous collagen fibers arranged randomly. When it becomes inflamed, a dangerous disease occurs - scleritis, the untimely treatment of which can lead to loss of vision.

Description and types of disease

Scleritis is a severe pathology of the visual apparatus, which is characterized by the presence of inflammation in all layers of the sclera. As a rule, this process is unilateral, but in some cases both eyes can be affected. This disease is less common in men than in women.

When the sclera becomes inflamed, a dangerous disease occurs - scleritis.

Scleritis in childhood is a fairly rare occurrence. The cause of the development of the disease is the inability of the child’s body to actively resist infections. In children, this process is very painful and can cause vision impairment. The formation of pathology in school-age children and adolescents is facilitated by metabolic disorders, allergic and autoimmune diseases.

There are three degrees of severity of the disease:

Easy. A small area of the eye is affected and reddened. This defect does not affect daily activity.
Average. The lesion can be unilateral or bilateral. The patient experiences headaches, lacrimation, and poor health.
Heavy. Inflammation covers the entire pericorneal zone (marginal vascular network of the cornea). Painful sensations are pronounced, visual disturbances occur.

Based on localization, the following types of pathology are distinguished:

Front. Inflammation occurs in the anterior part of the sclera. In this case, swelling and discoloration of the tissues are observed.
Rear. This form of the disease is rare and most often occurs against the background of pathologies that affect the entire body. It is characterized by thinning of the sclera in the posterior part of the eye, pain, and limited eye mobility.

In turn, anterior scleritis has several forms:

Nodular. This form is characterized by the appearance of fixed nodules on the surface of the sclera.
Diffuse. Inflammation covers the entire surface of the sclera or most of it. In this case, the vascular pattern is disrupted.
Necrotic. The most complex form of pathology. It causes severe pain and can lead to perforation (damage) of the sclera.

Sometimes the disease can occur in a purulent form, which is characterized by the formation of a small swelling in the eye filled with pus. Treatment of this pathology is carried out exclusively by surgery.

Types of sclerite - gallery

Reasons for development

There are several main causes of the disease:

systemic pathologies. In half of the cases, the disease occurs against the background of Wegener's granulomatosis, recurrent arthritis, polyarthritis nodosa;
surgical intervention. Postsurgical scleritis develops within 6 months after surgery. Characterized by the appearance of an inflamed area with signs of necrosis in the area of surgical manipulation;
injuries, chemical burns, exposure to ionizing radiation;
viruses, bacteria, fungi.

Predisposing factors to the development of the disease:

female;
decrease in the body's defenses;
chronic inflammatory processes in the nasopharynx;
endocrine diseases, metabolic disorders;
work that requires eye strain.

Eye injuries - video

Signs and symptoms of the disease

Painful sensations. The intensity of pain depends on what type of pathology is diagnosed. The nodular form is characterized by minor discomfort. With a pronounced inflammatory process with destruction of the sclera, very intense shooting pains occur, radiating to the temporal region, eyebrows and jaws.
Hyperemia (redness). May be limited or widespread.
Tearing. Occurs when nerve endings are irritated.
Vasodilation.
Protrusion of the eyeball.
Spots on the sclera of a yellowish tint. This phenomenon indicates the development of necrosis or melting of the sclera. Sometimes this is the only, but very dangerous manifestation of the disease.
Posterior scleritis is manifested by swelling of the eyelids and retina, and retinal detachment.

The disease can occur without pronounced symptoms. Therefore, it is important to pay attention to even minor discomfort, which is a reason to visit a doctor.

Diagnostics

To diagnose scleritis, the following methods are used:

Anamnesis collection. During the interview, the specialist must find out whether the patient has complaints from other organs, whether he suffers from connective tissue diseases, and whether similar signs have occurred in the past. In some cases, additional examination by a therapist or rheumatologist may be necessary.
Ophthalmoscopy. This method allows you to examine the retina, optic nerve and choroid. During the study, a special device is used that emits directional light.
Visometry. The method involves the use of special tables to test visual acuity. The study allows us to identify astigmatism and other vision defects that arise as a result of the disease.
Biomicroscopy. Using a slit lamp, the doctor examines the eyes under high magnification.
Ultrasound. This research method is used if the development of posterior scleritis is suspected. In some cases, a CT scan may be necessary.
Smear and bacteriological examination. Necessary in case of infectious nature of inflammation.

Due to the similarity of symptoms, it is important to differentiate scleral inflammation from pathologies such as:

conjunctivitis. The disease is characterized by inflammation of the membrane that lines the inner surface of the eyelids, lacrimation and a feeling of sand in the eye;
episcleritis. This condition is characterized by damage to the superficial layers of the sclera, in contrast to scleritis, in which inflammation penetrates much deeper;
iritis This pathology is characterized by local redness along the edge of the cornea; pain does not occur when pressed;
iridocyclitis. Inflammation covers the iris, ciliary body, a change in their color, and constriction of the pupil are observed.

Treatment of scleral inflammation

Depending on the causes of the disease, the method of treatment is determined. To get rid of unpleasant symptoms, it is necessary to eliminate the factors that contributed to the appearance of the pathology. Most often, treatment is carried out at home; hospitalization is needed only in severe forms of the disease or the development of serious complications.

Drugs for the treatment of scleritis - table

Group of drugs	Name	Destination purpose
Topical corticosteroids	Hydrocortisone; Oftan-dexamethasone.	Preparations in the form of drops or ointments reduce inflammation. In some cases, corticosteroids are prescribed as injections under the conjunctiva.
Nonsteroidal anti-inflammatory drugs	Diclofenac; Methindol; Diklak.	Reduce pain, relieve (eliminate) inflammation.
Enzyme preparations	Alidase; Infestations.	These sterile solutions are dropped into the eyes to speed up the resorption of secretions.
Opioid analgesics	Ethylmorphine	It is prescribed only in cases of extreme necessity (unbearable pain), as addiction may develop.
Antihypertensive drops	Visofrine; Atropine sulfate; Platyfillin;	They are used in cases of damage to the iris and increased intraocular pressure.
Systemic corticosteroids	Decortin;	Necessary if a person has intolerance to non-steroidal anti-inflammatory drugs, with severe disease, scleral necrosis.
Immunosuppressants	Cyclophosphamide; Cyclosporine.	Such drugs should be prescribed exclusively by a rheumatologist if the patient suffers from connective tissue diseases. Also, indications for the use of such drugs are resistance to corticosteroids and necrotic lesions of the sclera.
Antibacterial drugs: local; systemic.	Tobrosopt; Levomycetin.	Drugs in the form of drops are prescribed for the purulent form of the disease, the formation of an abscess, or if the pathology is caused by bacteria. In severe cases, subconjunctival injections of drugs are necessary. Local use of antibacterial drugs is combined with their oral or intramuscular administration.
Antibacterial drugs: local; systemic.	Streptomycin; Levoflox.

Medications for the treatment of scleritis - gallery

Pharmadex reduces inflammation
Movalis eliminates pain Lidaza accelerates the resorption of released secretions
Betoptic reduces intraocular pressure Prednisolone is prescribed for scleral necrosis Azathioprine is necessary if the pathology is caused by connective tissue diseases Floxal is prescribed for the purulent form of the disease
Amoxil helps get rid of severe forms of the disease

Physiotherapy

After the end of the acute stage of the disease, the use of physiotherapeutic methods of treatment is recommended:

Electrophoresis. Electrodes lubricated with a drug are applied to the affected tissues. Under the influence of electric current, the drug penetrates directly into the area of inflammation. The medicine is selected individually (depending on the causes of the pathology).
UHF therapy. The thermal effect of a high frequency electromagnetic field helps eliminate pain and relieve inflammation.
Magnetotherapy. The magnetic field promotes vasodilation, eliminates pain and inflammation, accelerates the healing process and tissue restoration.

Surgery

This method of treatment is used in advanced cases, with damage to the deep layers of the sclera, cornea, and iris. Surgical intervention is also necessary for suppuration of the sclera. If this membrane is noticeably thinned, it is transplanted from a donor. If the cornea is involved in the process and there is a sharp decrease in visual acuity, a corneal transplant is necessary.

Folk remedies

It is impossible to cure scleritis using folk remedies. This therapy can only be used in combination with taking medications and only after consulting a doctor.

Black tea. An effective and easy to prepare product. Leaf tea should be brewed, cooled, soaked in a swab and applied to the affected eye.
Aloe. To prepare the medicine, you will need pharmaceutical aloe extract in ampoules, which is diluted with purified water (1:10). The solution should be instilled into the eyes 3 times a day.
Clover infusion. To prepare the medicine:
- 1 tbsp. l. plant flowers are poured with 1 tbsp. boiling water;
- leave for 30 minutes.
- The product is used in the form of compresses on the affected organ.
Infusion of medicinal herbs.
- burdock root, chamomile and cornflower flowers are mixed in equal quantities;
- 1 tbsp. the collection is poured with a glass of boiling water;
- leave for 20 minutes, filter. Use eye wash or compresses.

The sclera covers the outside of the eyeball. It belongs to the fibrous membrane of the eye, which also includes. However, what distinguishes the sclera from the cornea is that it is considered an opaque tissue because the collagen fibers that form it are arranged randomly.

Sclera of the eye

The main function of the sclera is to provide high-quality vision. This occurs due to the fact that light rays simply cannot penetrate the scleral tissue, which would cause blinding. The main functions of the sclera also include protecting the inner membranes of the eye from external damage and supporting the structures and tissues of the eye that are located outside the eyeball:

oculomotor muscles;
ligaments;
vessels;
nerves.

Being a dense structure, the sclera is also involved in maintaining an optimal level of intraocular pressure and the outflow of intraocular fluid through the Helmet canal.

Deeper layers

The sclera itself consists of fibrocytes and collagen. These components are quite important for the body as a whole. The first group of substances takes an active part in the production of collagen itself, as well as in the separation of its fibers. The inner, very last layer of tissue is called the “brown plate”. It contains a huge amount of pigment, which determines the specific shade of the eye shell.

Certain cells called chromatophores are responsible for coloring such a plate. They are contained in the inner layer in large quantities. The brown plate most often consists of a thin fiber of the sclera, as well as a slight admixture of the elastic component. On the outside, this layer is covered with endothelium.

Burst vessels in the sclera

All blood vessels and nerve endings that are located in the sclera pass through emissaries - special channels.

Now let's take a closer look at each layer of the sclera:

The episcleral layer has a good blood supply and is connected to the outer, fairly dense teno capsule of the eye. The anterior parts of the episclera are considered to be the richest in blood flow, since blood vessels pass to the anterior part 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, that produce collagen.
The inner layer of the sclera is externally described as a brown plate, as it contains a lot of chromatophores.

What functions does the sclera perform?

The functions of the sclera are quite diverse. The first of them is due to the fact that collagen fibers inside the tissue are not arranged in a strict order. Because of this, light rays are unable to penetrate the sclera. This fabric protects the retina from intense exposure to light and sunlight. It is thanks to this function that a person is able to see quite well.

This fabric is intended not only to protect the eyes from intense light, but also from various damage. Including those that are physical or chronic in nature. In addition, the sclera also protects the organs of vision from the effects of harmful environmental factors.

Also, some experts highlight another important function of this tissue. Conventionally, it can be called a frame structure. It is the sclera that is a high-quality support and reliable element for attaching ligaments, muscles and other components of the eye.

Methods for diagnosing scleral diseases

The most common diagnostic methods include:

visual inspection;
biomicroscopy – a study carried out under a microscope;
ultrasound diagnostics.

Congenital diseases of the sclera

The sclera has a fairly simple structure, but there are certain diseases and pathologies of the sclera. We should also not forget that such tissue performs important functions and if any disturbances occur, the functioning of the visual apparatus as a whole sharply deteriorates. Diseases can reduce visual acuity and lead to irreparable consequences. Diseases of the sclera can be not only congenital, but also caused by various irritants.

A pathology called blue sclera can often occur as a result of genetic predisposition and improper formation of the tissues connecting the eyeball in the womb. The unusual shade occurs due to the small thickness of the layers. The pigment of the eye shell is visible through the thin sclera. This pathology can often occur with other eye anomalies and with disturbances in the formation of hearing organs, bone tissue and joints.

Most often, diseases of the sclera are congenital and include::

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

Melanosis is a serious problem, so you should immediately contact an ophthalmologist.

Acquired ailments

Inflammation of the sclera is quite common. Diseases that may appear as a result of such a process deserve special attention. The development of such ailments in the future can provoke not only general disruptions in the functioning of certain systems of the human body, but also infections.

The main symptoms include:

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

Quite often, pathogenic organisms penetrate the tissues of the outer eye membrane with the flow of lymph or blood. This is the main cause of the inflammatory process.

Now you know what the sclera is and what diseases of this tissue exist. Treatment of all her ailments begins with diagnosis and consultation with a doctor. Only a qualified specialist can prescribe treatment for the disease after identifying all the symptoms. If scleral diseases develop, it is recommended to immediately contact an ophthalmologist. The specialist, in turn, must conduct a series of studies. After the diagnosis is made, therapy is prescribed.

If the disease was caused by a disorder in other body systems, then treatment will be aimed at eliminating the underlying cause. Only after this will measures be taken to restore vision. We hope this information was useful and interesting.

The sclera is the outer layer of the human eye, occupying the maximum area.

Normally it is painted matte white, but may have a bluish tint. Pointed episodic brownish-grayish coloring of spots with a diameter not exceeding 0.5 mm in the area of passage of special holes, emissaries, is acceptable.

On the outer side, the sclera is adjacent to the cornea of the eye, and its inner surface has many holes that serve as guides for visual fibers collected in bundles. Between the sclera and the cornea, in the area of their contact, there is a groove 0.75 mm deep. Its back part has a special thickening called the scleral ridge.

The density and thickness of the fibrous capsule varies over a fairly significant range, ranging from 0.3 mm to 1.2 mm. The sclera is thickest on the inside; in the area where the optic nerve passes through it, it reaches a thickness of 1.2 mm, and its rear part is the thinnest, and, as already mentioned, riddled with special holes, emissaries. In the equatorial zone, the thickness of the sclera is approximately 0.4 mm.

Histology of the sclera

Histologically, the sclera consists of dense connective tissue cells with increased strength and elasticity. The connective tissue is collected in bundles and special plates, which in themselves already have sufficient density, but they are additionally intertwined and twisted in different directions. This structure provides the spherical fibrous capsule with sufficient elasticity, high strength and resistance.

These specific connective tissue cells are called fibrocytes, highly differentiated cells that participate in the formation of fibrous structures and produce large quantities of the fibrillar protein collagen. Fibrocytes have a spindle shape with a large number of processes and have a great ability for phagocytosis.

Pigmentation of the brown lamina, the inner layer of the sclera, is provided by specific chromatophore cells. And the brown plate itself is formed by thinner scleral fibers, covered on the outside with endothelial cells.

Structure of the sclera

The fibrillar membrane of the human eye has a multilayer structure (see photo) and consists of the following layers:

episcleral (otherwise called episclera) - its outer layer, not dense in structure, penetrated by numerous blood vessels, and the most intense blood supply is observed in the outer part of the episcleral layer. It binds to the very dense outer Tenon's capsule of the eyeball.
The sclera itself is the next layer, which is formed from fibrillar protein, which forms the basis of the body’s connective tissue, collagen and the connective tissue cells of fibrocytes that produce collagen and separate its fibers.
The inner layer, the subconjunctival layer, has a relatively looser structure, contains significant amounts of brown pigment and is called the brown plate.

The scleral tissue is penetrated by a large number of blood vessels, as well as nerve fibers leading to the cornea or the uveal tract of the organ of vision. The scleral capsule itself is poor in blood vessels. The deep surface of the sclera is adjacent to the uveal tract of the eyeball.

Functional load of the fibrillar membrane of the eye

The sclera serves as a kind of frame for the entire organ of vision, giving it a certain spherical shape, and all the eye membranes, located deeper, rest on it. It essentially acts as a dense opaque fibrous capsule of the organ of vision, covering more than ¾ of its entire surface, and serves as its protective shell. The sclera protects the eyeball from physical and mechanical influences, and also protects the eye from the negative influence of the environment.

Due to its structure and structure, the sclera is completely opaque and light rays are not able to penetrate through it, that is, in addition to mechanical protection of the organ of vision, the fibrous capsule also protects the photosensitive retina of the eye from exposure to external lighting of excessive intensity, thereby maintaining adequate performance by the organ of vision their functions.

Thus, the sclera bears the following main functional load:

Supports the implementation of normal high-quality visual function;
Performs a protective function, as it protects all the inner membranes of the eye;
Performs a supporting function, as it serves as a frame for all structures and tissues of the organ of vision;
ensures normal outflow and circulation of intraocular fluid and maintains intraocular pressure at a normal level.

Pathological conditions of the sclera

There are genetically determined congenital pathologies of the scleral membrane of the eye, namely:

Blue sclera syndrome, in which the sclera is too thin and cannot fully perform its functions;
Congenital abnormalities of the structure of the collagen protein that forms the sclera;
Melanosis, in which characteristic highly pigmented areas appear on the surface of the sclera, due to the presence of which a number of complications can develop over time.

The sclera is also susceptible to inflammatory diseases caused by infectious agents or general dysfunctions of the body. Due to the fact that the sclera is essentially connective tissue, all pathological processes characteristic of systemic pathological conditions of connective tissue or collagenoses, for example, tuberculosis, scleroperirkeratitis, etc., can develop in it.

Pathological conditions such as:

Episcleritis, an inflammatory disease of the episcleral layer;
Scleritis, acute destructive inflammation of the deep layers of the sclera;
Staphyloma of the sclera, in which there is a strong protrusion of its thinned layers;
Ruptures of scleral tissue caused by mechanical damage.

Diseases of the sclera of any etiology can provoke quite severe disturbances in visual function, and therefore require timely and effective treatment. Therapy for scleral diseases can be invasive, medicinal or physiotherapeutic.

Diagnosis of pathological conditions of the fibrous membrane

To diagnose scleral diseases of any etiology, you need to undergo a qualified examination by an ophthalmologist. In addition to an external examination to make a diagnosis, the doctor may prescribe additional examinations, namely:

Biomicroscopy;
Ultrasound of the organs of vision.