Reflecting the transition in the process of phylogenesis from the gill circle of the blood circulation to the pulmonary, in a person during ontogenesis, aortic arches are first laid, which are then transformed into the arteries of the pulmonary and bodily circles of the blood circulation. At the 3-week-old embryo truncus arteriosus, leaving the heart, gives rise to two arterial trunks, called the ventral aorta (right and left). The ventral aorta travels upward, then back to the dorsal side of the embryo; here, passing along the sides of the notochord, they are already going in a downward direction and are called dorsal aorta. The dorsal aorta gradually converges with each other and in the middle part of the embryo merge into one unpaired descending aorta. As the embryo of the gill arches develops, the so-called aortic arch, or artery, forms in each of them; these arteries interconnect the ventral and dorsal aorta on each side. Thus, in the area of the gill arches, the ventral (ascending) and dorsal (descending) aortae are interconnected by means of 6 pairs of aortic arches.
In the future, part of the aortic arches and part of the dorsal aorta, especially the right, is reduced, and large primary and main arteries develop from the remaining primary vessels, namely: truncus arteriosus, as noted above, is divided by the frontal septum into the ventral part, from which the pulmonary trunk is formed, and dorsal, turning into ascending aorta. This explains the location of the aorta behind the pulmonary trunk. It should be noted that the latter, due to the current of blood, a pair of aortic arcs, which in lungfish and amphibians gains connection with the lungs, is transformed in humans into two pulmonary arteries – right and left, branches of truncus pulmonalis. At the same time, if the right sixth aortic arch remains only on a small proximal segment, then the left remains all over, forming ductus arteriosus, which connects the pulmonary trunk with the end of the aortic arch, which is important for the circulation of the fetus (see below). The fourth pair of aortic arches remains on both sides all over, but gives rise to different vessels. The left 4th aortic arch together with the left ventral aorta and part of the left dorsal aorta form the aortic arch, arcus aortae.
The proximal segment of the right ventral aorta turns into the brachiocephalic trunk, truncus blachiocephalicus, the right 4th aortic arch – into the beginning of the right subclavian artery extending from the named trunk, a. subclavia dextra. The left subclavian artery grows from the left dorsal aorta caudal to the last aortic arch. Dorsal aorta in the area between the 3rd and 4th aortic arches are obliterated; in addition, the right dorsal aorta is also obliterated from the place of the right subclavian artery to the junction with the left dorsal aorta.
The heart develops from two symmetric primordia, which then merge into a single tube located in the neck. Due to the rapid growth of the tube in length, it forms an S-shaped loop). The first contractions of the heart begin at a very early stage of development, when the muscle tissue is barely distinguishable. The S-shaped heart loop distinguishes the anterior arterial, or ventricular, part, which continues into the truncus arteriosus, which is divided into two primary aorta, and the posterior venous, or atrial, into which the yolk-mesenteric veins flow, vv. omphalomesentericae.
In this stage, the heart is single-cavity, its division into the right and left halves begins with the formation of the atrial septum. By growing from top to bottom, the septum divides the primary atrium into two – the left and right, and in such a way that subsequently the confluence of the hollow veins are in the right, and the pulmonary veins – in the left.
The septum of the atria has a hole in the middle, foramen ovale, through which the fetal part of the blood from the right atrium enters directly into the left. The ventricle is also divided into two halves by a septum, which grows from the bottom towards the atrial septum, without completing, however, the complete separation of the ventricular cavities.
Sulci, sulci interventriculares appear on the outside according to the boundaries of the ventricular septum. Completion of the septum formation occurs after the truncus arteriosus, in turn, is divided by the frontal septum into two trunks: the aorta and the pulmonary trunk. The partition dividing the truncus arteriosus into two trunks, extending into the ventricular cavity towards the ventricular septum described above and forming the pars membranacea septi interventriculare, completes the separation of the ventricular cavities from each other.
The right atrium is adjacent to the original sinus venosus, which consists of three pairs of veins: the common cardinal vein, or the Cuvier duct (brings blood from the entire body of the embryo), the yolk vein (brings blood from the yolk sac) and the umbilical vein (from the placenta). During the 5th week, the hole leading from the sinus venosus to the atrium expands greatly, so that eventually the wall becomes the wall of the atrium itself. The left process of the sinus, together with the left duct duct that flows here, remains and remains as sinus coronarius cordis.
When flowing into the right atrium, sinus venosus has two venous valves, valvulae venosae dextra et sinistra. The left valve disappears, and valvula venae cavae inferioris and valvula sinus coronarii develop from the right valve. As a developmental abnormality, the 3rd atrium can be obtained, representing either the stretched coronary sinus into which all the pulmonary veins fall, or a separated part of the right atrium.
The large (bodily) circulation of blood serves to deliver nutrients and oxygen to all organs and tissues of the body and remove metabolic products and carbon dioxide from them. It begins in the left ventricle of the heart, from which the aorta extends, which carries arterial blood. Arterial blood contains nutrients and oxygen necessary for the vital functions of the body, and has a bright scarlet color. The aorta forks into arteries that go to all organs and tissues of the body and pass into the thickness of the arterioles and further into the capillaries. The capillaries, in turn, are collected in the venules and further into the veins. Through the wall of capillaries, metabolism and gas exchange occur between the blood and body tissues. The arterial blood flowing in the capillaries gives off nutrients and oxygen and in return receives metabolic products and carbon dioxide (tissue respiration). As a result, the blood entering the venous bed is poor in oxygen and rich in carbon dioxide and therefore has a dark color – venous blood; in case of bleeding, it is possible to determine by blood color whether the artery or vein is damaged. The veins merge into two large trunks – the upper and lower hollow veins, which flow into the right atrium. This part of the heart ends with a large (bodily) circle of blood circulation. In addition to the large circle, there is a third (heart) circulation that serves the heart itself. It begins with the coronary arteries of the heart emerging from the aorta and ends with the veins of the heart. The latter merge into the coronary sinus, which flows into the right atrium, and the small veins open into the atrial cavity directly.
Regional blood circulation. The total circulatory system with its large and small circles of blood circulation functions differently in different areas and organs of the body, depending on the nature of their function and functional needs at the moment. Therefore, besides the general circulation, there are local, or regional (from the Latin. Regio – region), blood circulation. It is carried out by trunk and organ vessels, which have their own special structure in each separate organ. To understand the regional circulation of blood matters the correct understanding of the microcirculation of blood.
The small (pulmonary) circulation serves to enrich the blood with oxygen in the lungs. It begins in the right ventricle, where all the venous blood that enters the right atrium passes through the right atrioventricular (atrioventricular) opening. From the right ventricle comes the pulmonary trunk, which, approaching the lungs, is divided into the right and left pulmonary arteries.
The latter branch into the lungs into arteries, arterioles, precapillaries, and capillaries. In capillary nets that interweave pulmonary vesicles, the blood gives up carbon dioxide and receives in exchange a new supply of oxygen (pulmonary respiration). Oxidized blood becomes scarlet again and becomes arterial. The oxygen-rich arterial blood flows from the capillaries into the venules and the veins, which, merging into four pulmonary veins (but two on each side), flow into the left atrium.
In the left atrium, the small (pulmonary) circulatory circuit ends, and the arterial blood that enters the atrium passes through the left atrioventricular orifice into the left ventricle, where the great circulation begins.
The microcirculatory bed is not a mechanical sum of various vessels, but a complex anatomical and physiological complex consisting of 7 links (5 blood vessels, lymphatic and interstitial) and providing the main vital process of the body – metabolism. Therefore, V. V. Kupriyanov regards it as a microcirculation system.
The structure of the microvasculature has its own characteristics in different organs, corresponding to their structure and function. Thus, in the liver there are wide capillaries – hepatic sinusoids, which receive arterial and venous (from the portal vein) blood. In the kidneys there are arterial capillary glomeruli. Special sinusoids are characteristic of the bone marrow, etc.
Microcirculation fluid is not limited to microscopic blood vessels. The human body is 70% composed of water, which is contained in cells and tissues and makes up the bulk of blood and lymph. Only xls of the whole fluid is in the vessels, and the remaining 4/5 of it is contained in the plasma of cells and in the extracellular medium. Microcirculation of the fluid is carried out, in addition to the circulatory system, also in the tissues, in the serous and other cavities, and in the path of transport of lymph.
From the microvasculature, blood flows through the veins, and lymph through the lymphatic vessels, which ultimately fall into the cardiac veins. Venous blood containing lymph that has joined it, flows into the heart, first into the right atrium, and from it into the right ventricle. From the latter, venous blood enters the lungs through the small (pulmonary) circulation.
Blood circulation begins in the tissues, where the metabolism takes place through the walls of the capillaries (blood and lymph). The capillaries constitute the main part of the microcirculatory bed, in the colum microcirculation of blood and lymph occurs.
Lymphatic capillaries and interstitial spaces also belong to the microcirculatory bed. Microcirculation is the movement of blood and lymph in the microscopic part of the vascular bed.
Microcirculatory bed, according to V. V. Kupriyanov, includes 5 links:
1) arterioles as the most distal parts of the arterial system,
2) precapillaries, or precapillary arterioles, which are intermediate between arterioles and true capillaries;
4) postcapillaries, or postcapillary venules,
5) venules, which are the roots of the venous system.
All these links are equipped with mechanisms that ensure the permeability of the vascular wall and the regulation of blood flow at the microscopic level. The microcirculation of blood is regulated by the work of the arterial muscles and arteriol, as well as the special muscle sphincters, the existence of which was predicted by I. Sechenov and called them “cranes”. Such sphincters are in pre- and postcapillaries. Some vessels of the microvasculature (arterioles) perform predominantly distribution function, and the rest (precapillaries, capillaries, postcapillaries and venules) predominantly trophic (exchange).
At each given moment only a part of the capillaries (open capillaries) functions, and the other remains in reserve (closed capillaries).
In addition to these vessels, the Soviet anatomists proved that they belong to the microcirculatory channel of arterio-venous anastomoses, which are present in all organs and represent the paths of the shortened flow of arterial blood into the venous channel, bypassing the capillaries. These anastomoses are divided into true anastomoses, or shunts (with locking devices capable of blocking the flow of blood, and without them), and inter-arterioles, or half-shunts. Due to the presence of arteriovenous anastomoses, the terminal blood flow is divided into two ways of blood flow: 1) transcapillary, which serves for metabolism, and 2) extracapillary juxtacillary (from lat. Juxta – near, beside) flow of blood necessary for regulation of hemodynamic balance; the latter is due to the presence of direct connections (shunts) between the arteries and veins (arteriovenous anastomoses) and arterioles and venules (arteriolenovenular anastomoses).
Due to the extracapillary blood flow, if necessary, the capillary bed is unloaded and the blood transport in the organ or a given area of the body is accelerated. It is like a special form of a roundabout, collateral, blood circulation.
The contraction of the muscular layer of the veins is also important, which in the veins of the lower half of the body, where the conditions for venous outflow is more complicated, is more developed than in the veins of the upper body. The reverse flow of venous blood is prevented by special devices of the veins – valves that make up the peculiarities of the venous wall. Venous valves consist of a fold of endothelium containing a layer of connective tissue. They face the free edge towards the heart and therefore do not prevent the blood from flowing in this direction, but keep it from returning back. Arteries and veins usually go together, with small and medium arteries accompanied by two veins, and large – one. Except for some deep veins, this rule excludes mainly superficial veins reaching the subcutaneous tissue and almost never accompanying arteries.
The walls of blood vessels have their own serving thin arteries and veins, vasa vasorum. They depart either from the same trunk, the wall of which is supplied with blood, or from the neighboring one and pass in the connective tissue layer surrounding the blood vessels and more or less closely connected with their outer sheath; This layer is called the vascular vagina, vagina vasorum. In the wall of arteries and veins there are numerous nerve endings (receptors and effectors) connected with the central nervous system, due to which the nervous regulation of blood circulation is carried out by the mechanism of reflexes. Blood vessels are extensive reflexogenic zones that play a large role in the neuro-humoral regulation of metabolism. Accordingly, the functions and the structure of the various departments and the features of innervation all the blood vessels in recent times have been divided into 3 groups:
1) the heart vessels that begin and end both circles of circulation, the aorta and the pulmonary trunk (i.e., elastic arteries), hollow and pulmonary veins;
2) the great vessels that serve for the distribution of blood throughout the body. These are large and medium sized extraorgan arteries of the muscular type and extraorgan veins;
3) organ vessels providing exchange reactions between the blood and the parenchyma of organs. These are intraorgan arteries and veins, as well as links in the microvasculature.
An arteriole differs from an artery in that its wall has only one layer of muscle cells, thanks to which it performs a regulatory function. Arteriole proceeds directly into the precapillary, in which muscle cells are scattered and do not constitute a continuous layer. The precapillary differs from arterioles in the fact that it is not accompanied by a venule.
Numerous capillaries depart from the precapillary.
Capillaries are the thinnest vessels that perform the exchange function. In this regard, their wall consists of a single layer of flat endothelial cells, permeable to substances and gases dissolved in a liquid. Anastomozirovaya widely between themselves, the capillaries form a network (capillary network), turning into postcapillary, built similarly to precapillary. Postcapillary continues into the venula, accompanying arterios. Venules form thin initial segments of the venous bed that make up the roots of the veins and pass into the veins.
Veins (lat. Vena, Greek phlebs; hence phlebitis – inflammation of the veins) carry blood in the opposite direction to the arteries, from organs to the heart. Their walls are arranged according to the same plan as the walls of the arteries, but they are much thinner and have less elastic and muscular tissue, due to which empty veins fall, and the lumen of the arteries in the transverse section gapes; veins, merging with each other, form large venous trunks – veins that flow into the heart.
Veins widely anastomose among themselves, forming venous plexus.
The movement of blood through the veins is due to the activity and the suctioning action of the heart and chest cavity, in which negative pressure is created during inhalation due to the pressure difference in the cavities and also due to the reduction of the skeletal and visceral muscles of the organs and other factors.
Arteries. The wall of the arteries. Capillaries Veins. The circulatory system consists of a central organ – the heart – and closed tubes of various calibers in conjunction with it, called blood vessels (Latin vas, Greek angeion – vessel; hence, angiology). With its rhythmic contractions, the heart drives the whole mass of blood, contained in the vessels.
Arteries. The blood vessels that go from the heart to the organs and carry blood to them are called arteries (aeg – air, tereo – contain; arteries on corpses are empty, which is why they used to be considered as air tubes).
The wall of the arteries consists of three shells. Inner shell, tunica intima. lined on the lumen of the vessel by the endothelium, under which the subendothelium and the inner elastic membrane lie; medium, tunica media, built from loose muscle fibers, myocytes, alternating with elastic fibers; the outer sheath, tunica externa, contains connective tissue fibers. The elastic elements of the arterial wall form a single elastic frame that acts as a spring and determines the elasticity of the arteries.
As they move away from the heart, arteries divide into branches and grow smaller and smaller. The arteries closest to the heart (the aorta and its large branches) perform mainly the function of conducting blood. In them to the fore the anti-stretching of a mass of blood, which is thrown out by a heart beat, comes forward. Therefore, in their wall structures of a mechanical nature are relatively more developed, i.e., elastic fibers and membranes. Such arteries are called elastic type arteries. In medium and small arteries, in which the inertia of the cardiac impulse weakens and requires its own contraction of the vascular wall for further blood advancement, the contractile function prevails. It is provided with a relatively large development in the vascular wall of muscle tissue. Such arteries are called muscular arteries. Individual arteries supply blood to entire organs or parts of them.
In relation to the organ, there are arteries that go beyond the organ, before entering it – extraorgan arteries, and their continuations that branch out inside it – intraorgan, or ingraorganic arteries. Lateral branches of the same stem or branches of different trunks can be connected to each other. Such a combination of vessels before disintegration of them into the capillaries is called anastomosis, or fistula (stoma – mouth). The arteries that form the anastomoses are called anastomosing (most of them). Arteries that do not have anastomoses with adjacent trunks before moving into the capillaries (see below) are called end arteries (for example, in the spleen). The terminal, or terminal, arteries are more easily blocked with a blood stopper (thrombus) and predispose to the formation of a heart attack (local organ death). The last branchings of the arteries become thin and small and therefore stand out under the name of arterioles.
The eyes are located in the depressions of the skull, called the eye sockets, the eye is strengthened here with the help of four direct and two oblique muscles that control its movements. The human eyeball has a diameter of about 24 mm and weighs 6 to 8 g. The eyeball is formed by three membranes of the eyeball and is covered with conjunctiva in front.
The wall of the eye consists of three concentric layers:
1. sclera and cornea. Outside the cornea protects the conjunctiva – a thin transparent layer of cells, transient in the epithelium of the eyelids. Conjunctiva does not enter the corneal area covering the iris. The eyelids protect the cornea from mechanical damage, and the retina from too bright light. The outer surface of the cornea is covered with a thin layer of tear fluid.
2. choroid, ciliary body, lens and iris.
3. the retina. The retina is the inner lining containing photoreceptor cells (rods and cones), as well as the body and axons of the neurons that form the optic nerve. In the place where the optic nerve comes out of the eye, the retina does not contain any rods or cones, this place is called a blind spot of the retina. The most sensitive area of the retina, containing only cones, is the central fossa fossa. The beam of light is focused on it most accurately.
The shape of the eye is maintained by hydrostatic pressure (25 mm Hg) of aqueous humor and vitreous.
The outer shell of the eyeball, the sclera, is under conjunctiva. It consists mainly of collagen fibers, usually affected by autoimmune diseases.
Medium, vascular, shell provides the production and outflow of aqueous humor. The defeat of the choroid is most often caused by immunocomplex allergic reactions and allergic reactions of the delayed type.
The inner shell of the eyeball, the retina, consists of nerve elements and is a peripheral part of the visual analyzer.
The conjunctiva is the mucous lining the posterior surface of the eyelids and the anterior surface of the sclera. It consists of epithelium and connective tissue basis. Normally, mast cells (about 6000 / mm-3) lymphocytes and granulocytes are detected only in the stroma of the conjunctiva, directly under the epithelium. When inflammation occurs, for example, in spring conjunctivitis, conjunctivitis with papilla hyperplasia, these cells appear in the epithelium.
Conjunctiva is rich in lymphatic vessels. The lymph flows from the lateral part of the conjunctiva to the parotid lymph nodes located in front of the auricle trestle, from the medial lymph node to the submandibular lymph nodes. The membranes of the eyeball are devoid of lymphatic vessels.
The vascular membrane and its derivatives – the iris and ciliary body – contain a dense network of vessels. The ciliary body produces aqueous humor, which, like urine and CSF, is a plasma filtrate.
In allergic diseases of the eye can affect any of the membranes of the eyeball. Conjunctiva and tear film on its surface are the first barrier to infection, airborne allergens, organic and inorganic compounds.
Eyes: ophthalmologic examination
First examine the eyelids, then the conjunctiva.
When conjunctivitis is defined: edema, hyperemia, hypertrophy of the papillae and follicles on the conjunctiva of the eyelids and the eyeball. The follicles are larger than the papillae, have the appearance of colorless, grayish or yellow grains ranging from tenths to a few millimeters, do not have their own blood vessels. In the center of each papilla, on the contrary, there is a vessel. When conjunctivitis necessarily palpate the parotid and submandibular lymph nodes: their increase is characteristic of infectious conjunctivitis and is not found in allergic conjunctivitis. Then, tearing, presence and character of discharge from the eyes are evaluated. With uveitis and cataract ophthalmoscopy.
Uveitis is often observed in autoimmune diseases, cataracts – in allergic diseases and long-term treatment with corticosteroids.
In the study of the anterior chamber of the eye assess the nature of the aqueous humor. The watery moisture may contain blood, which is evenly distributed in the anterior chamber or settles at its bottom, or pus, which usually settles at the bottom of the chamber. If the anterior chamber is shallow, glaucoma should be suspected. In this case, mydriatics are contraindicated. A rough estimate of the depth of the anterior chamber of the eye is possible with side lighting with a pen-flashlight.
Eyes: diseases, symptoms of diseases
Trichiasis – the growth of eyelashes in the direction of the eyeball – is caused by the deformation of the cartilage of the upper or lower eyelid, which leads to the twisting of the eyelid.
Constant contact of the eyelashes with conjunctiva leads to conjunctivitis, possibly corneal damage.
Tearing can be a consequence of increased production of tear fluid in case of allergies or obstruction of the tear ducts. The latter is often observed in chronic sinusitis and rhinitis. If you suspect a violation of the outflow of tear fluid in the eye instilled 2% solution of fluorescein. Normally, the dye disappears after 1 min.
Subconjunctival hemorrhage occurs with severe friction of the eyelids, vomiting, coughing, straining, often occurs without cause. With frequent subconjunctival hemorrhages, it is necessary to examine the blood coagulation system.
Pingvecula is a yellowish plaque on the conjunctiva of the eyeball, often located medially from the cornea. It occurs as a result of subepithelial deposition of collagen and proliferation of connective tissue, usually asymptomatic. With age, the pingvecula increases. The pinguecula is often confused with pterigia, which is a triangular proliferation of the conjunctiva that crawls onto the cornea from the medial side.
Flicheng – a small infiltrate in the form of a grayish node of a rounded shape, located in the region of the limbus, is often observed with tuberculosis, a staph infection, exhaustion.
Blepharitis is an inflammation of the eyelids.
Chalazion is a chronic granulomatous inflammation of the meibomian gland.
Barley – a small abscess on the conjunctiva or the skin of the eyelid, occurs as a result of purulent inflammation of the sebaceous gland.
Episcleritis and scleritis – inflammation of the outer membrane of the eyeball – sclera.
The amarotic cat’s eye, the white pupil, is observed in cataracts, Chediak-Higashi syndrome, retinoblastoma and retrolental fibroplasia.
Eyes: diseases, side effects of drugs
Side effects of agents used to treat eye diseases.
Beta-blockers for local use prescribed for glaucoma. It is assumed that they reduce the production of aqueous humor in the anterior chamber of the eye, which, in turn, leads to a decrease in intraocular pressure. Betaxolol is used as beta1-adrenergic blockers, – and nonselective beta-adrenergic blockers – levobunolol, metipranolol and timolol.
All beta-blockers for local use can cause bronchospasm, as they, bypassing the liver, immediately enter the lungs. However, beta1-blockers cause this complication much less frequently than non-selective beta-blockers.
Adverse reactions to the on / in the introduction of fluorescein during fluorescein angiography develop in 5% of patients. In 50% of them, these reactions develop repeatedly. Since the frequency of deaths in fluorescein angiography is 1: 220,000, and more than 200,000 such studies are conducted in the United States each year, an average of at least 1 person dies from fluorescein in the United States. When on / in the introduction of fluorescein anaphylactoid reaction develops, which in 2.9% of patients is accompanied by nausea, in 1.2% – vomiting, in 0.2% – hyperemia of the skin and urticaria and can lead to shock. It has been shown that with on / in the introduction of fluorescein increases the level of histamine in serum.
Skin tests to identify patients with a high risk of reaction to fluorescein are not informative. Avoid repeated reactions to fluorescein, using schemes for the prevention of anaphylactoid reactions to radiopaque substances, as a rule, fails.
Glaucoma: causes, symptoms, diagnosis and treatment of glaucoma
The term glaucoma implies an extensive group of diseases that are characterized by:
increased intraocular pressure (IOP)
damage to the optic nerve head, as well as retinal ganglion cells
narrowing the field of view
Glaucoma may occur regardless of age, but is most common in the elderly or senile.
Glaucoma is considered one of the main causes of irreversible blindness in the world according to the World Health Organization (WHO).
Intraocular fluid and ways of its outflow
Intraocular fluid (hereinafter VGZH) plays a huge role in maintaining the level of intraocular pressure. It is one of the sources of nutrition for intraocular structures (lens, cornea, trabecular apparatus, vitreous humor).
It is produced by the VGZH processes of the ciliary body, located behind the iris, and is collected in the back chamber of the eye. Next, most of the liquid, washing the lens, flows through the pupil, enters the anterior chamber and passes through the eye drainage system (trabecula and Schlemm’s canal), which is located in the corner of the anterior tail chamber. From the drainage system of the eye, the VGZH enters the output collectors (graduates), and then into the superficial veins of the sclera.
In this way, about 85% of the intraocular fluid flows, but there is another way of outflow, which flows about 15%.
The HAH may exit the eye, seeping through the stroma of the ciliary body and the sclera into the veins of the choroid and sclera. This outflow pathway is called uveoscleral.
There is a certain equilibrium between the production of IGL and its outflow. If this balance is disturbed, the level of intraocular pressure changes, which is a prerequisite for the development of glaucoma.
Causes and mechanisms of development of glaucoma
Glaucoma is a multifactorial disease, for the development of which a number of causes (risk factors) are needed:
individual anatomical features or abnormal structures of the eye
pathology of the cardiovascular, nervous and endocrine systems.
Various combinations of these risk factors trigger the mechanism for the development of glaucoma, which can be represented as stages:
increased production of intraocular fluid and / or deterioration of its outflow from the cavity of the eyeball;
an increase in intraocular pressure (IOP) is higher than the tolerant (tolerable) for the optic nerve;
ischemia (impaired blood supply) and hypoxia (lack of oxygen) of the optic nerve head;
development of glaucomatous optic neuropathy followed by
atrophy (death) of the optic nerve.
Forms of glaucoma
The following main types (forms) of glaucoma are distinguished:
primary early congenital glaucoma,
infantile congenital glaucoma,
concomitant congenital glaucoma
Adult primary glaucoma:
primary open angle glaucoma (POAG) – multifactorial disease associated with involutional and age-related changes in the eye)
primary angle-closure glaucoma (PZUG) – (the main cause of the disease is the closure of the anterior chamber angle, where the drainage system of the eye is located, by the iris root)
secondary glaucoma in adults: (a consequence of other ocular or somatic diseases, in which there is an involvement of structures involved in the production or outflow of IGL)
Symptoms of glaucoma
Predominantly, glaucoma is asymptomatic, and the patient notes a decrease in vision, when already 50% of the optic nerve fibers are permanently damaged.
Non-specific symptoms of glaucoma are:
feeling of heaviness in the eyes
narrowing of the field of view
blurred vision in the dark
“rainbow circles” before the eyes when looking at the source of light
Nonspecific symptoms are called because they may be characteristic of other ophthalmologic diseases.
In case of closed-angle glaucoma and the onset of an acute attack, the symptoms are severe: severe eye pain, headache, redness of the eye, nausea, vomiting.
But if any of the above symptoms appear, you should immediately consult a doctor.
Diagnosis of glaucoma
For the diagnosis of glaucoma and determine the method of treatment of glaucoma, it is necessary to conduct a thorough diagnostic examination, which should include:
visometry (determination of visual acuity)
refractometry (determination of the optical power of the eye – refraction)
perimetry (definition of peripheral vision)
tonometry (determination of intraocular pressure)
biometrics (determining the depth of the anterior chamber, the thickness of the lens, the length of the eye)
biomicroscopy (examination of tissues and media of the eye with a slit lamp)
gonioscopy (study of the structure of the anterior chamber angle)
ophthalmoscopy (fundus examination with assessment of the state of the optic nerve and retina)
Conservative treatment of glaucoma includes drugs that reduce the production of intraocular fluid and / or improve its outflow, hemodynamic (improves blood flow) and neuroprotective (protecting nerve fibers) drugs.
With insufficient effectiveness of conservative therapy (increased IOP, narrowing of the visual field, progression of optical neuropathy), surgical treatment is indicated.
Surgical treatment of glaucoma is aimed at eliminating intraocular blocks (obstacles) in the path of intraocular fluid movement or at creating a new outflow path.
There are many types of operations for glaucoma, but the most successful are:
non-penetrating deep sclerectomy
– with drainage of the anterior chamber angle
– without drainage of the anterior chamber angle
After cutting the conjunctiva and the formation of superficial and deep scleral flaps, the Schlemm canal’s outer wall is removed, thus enhancing the outflow of intraocular fluid through the drainage system of the eye. Sometimes, in the area of excision of the Schlemm’s external wall, drainage is implanted to enhance the effectiveness of the operation.
The advantages of this operation:
local drip anesthesia
performed without penetration into the cavity of the eye, which allows to avoid a number of complications (a sharp decrease in IOP, bleeding, detachment of the choroid, etc.)
Non-penetrating deep sclerectomy is a highly effective method for the surgical treatment of open-angle glaucoma.
penetrating deep sclerectomy
– with drainage of the anterior chamber angle
– without drainage of the anterior chamber angle
– with valve implantation
After cutting the conjunctiva and forming a superficial scleral flap, deep scleral layers are excised, then the anterior chamber is opened and part of the iris is excised, which allows the intraocular fluid to circulate freely in the anterior and posterior chambers of the eye. To enhance the efficiency of the outflow of IHL from the eye, a drainage or valve is implanted in the area of the operation.
Penetrating deep sclerectomy is a more traumatic operation, but its effectiveness is indisputable with angle-closure glaucoma and with the ineffectiveness of a previously non-penetrating operation.
It is worth remembering that timely diagnosis and the appointment of adequate conservative or surgical treatment allows you to maintain high vision in patients with glaucoma for a long period.