Cataract on the eye: symptoms, causes, treatment of clouding of the lens. Artificial lenses for the eyes

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Cataract represents eye disease, in which there is a clouding of one of the structural units of the human eye, namely, the lens. Normally, the lens of the eye is absolutely transparent, due to which light rays freely pass through it and are focused on the retina, from where the image of the "picture" of the surrounding world is transmitted to the brain via the optic nerve. Thus, the transparency of the lens is one of the necessary conditions for good vision, because, otherwise, the light rays will not even fall on the retina of the eye, as a result of which a person will not be able to see in principle.

A cataract is a disease in which the lens becomes cloudy and loses its transparency, as a result of which the bangs begin to see poorly. With a long course of cataracts, clouding of the lens can be so significant that a person is completely blind. The main manifestation of cataract is the appearance of a sensation of "fog" before the eyes, through which objects are seen as if through a haze, a layer of water or misted glass. In addition, cataracts worsen vision at night, impaired ability to recognize colors, double vision and increased sensitivity to bright light.

Unfortunately, the only treatment that completely eliminates cataracts is surgery, during which the cloudy lens is removed and a special transparent lens is inserted into the eye instead. But such an operation is not always necessary. So, if a person sees normally, then conservative treatment is recommended to stop the progression of cataracts and maintain vision at the current level, which will be an adequate replacement for surgery.

Brief description of the disease

Currently, according to the World Health Organization, cataract is the most common eye disease in the world. However, the frequency of its occurrence is different in people of different age groups. So, in people under 40 years of age, cataracts develop extremely rarely, and in this age group, cases of a congenital disease that developed in a child in the womb before he was born are recorded mainly. Among people 40-60 years old, cataract occurs in 15%, in the group of 70-80-year-olds the disease is already fixed in 25-50%, and among those who have crossed the 80-year mark, cataracts are detected to some extent in everyone. Thus, cataract is an urgent and frequently encountered medical problem, as a result of which the disease and methods of its treatment are intensively studied, due to which significant progress has been made in recent years in the success of therapy.

With a cataract, one of the structures of the eye is affected - the lens, which becomes cloudy. To understand the essence of the disease, it is necessary to know the position and functions of the lens in the system of the human visual analyzer.

So, the lens is a biconvex, elliptical, absolutely transparent structure located behind the iris (see Figure 1) with a maximum diameter of 9-10 mm.

Picture 1- The structure of the eye.

Since the lens is completely transparent, even with a careful look into the pupil or at the iris of the eye, it is not visible. By structure, the lens is a gel-like mass enclosed in a dense capsule of connective tissue that holds the necessary shape of the organ. The gel-like content is transparent, so that light rays pass through it freely. The shape of the lens is similar to an ellipse, which is extended from one corner of the eye to the other, and the curved surfaces adjacent to the pupil are optical lenses that can refract light rays. The lens does not contain blood vessels that would violate its complete transparency, as a result of which its cells are nourished by diffusion of oxygen and various necessary substances from the intraocular fluid.

According to the functional purpose, the lens plays a very important role. Firstly, it is through the transparent lens that light rays pass into the eye and are focused on the retina, from where the image for analysis and recognition is transmitted to the structures of the brain along the optic nerve. Secondly, the lens not only transmits light waves into the eye, but also changes the curvature of its surfaces in such a way that the rays are focused exactly on the retina. If the lens did not change its curvature, adjusting to different illumination intensity and distance of the objects under consideration, then the light rays passing through it would not focus exactly on the retina, as a result of which a person would see blurry, not clear images. That is, with a constant curvature of the lens, a person's vision would be poor, he would see like those suffering from myopia or hyperopia and not wearing glasses.

Thus, we can say that the main function of the lens is to ensure that the image of the surrounding world is focused directly on the retina. And for such focusing, the lens must constantly change its curvature, adjusting to the conditions of visibility of the environment. If an object is close to the eye, then the lens increases its curvature, thereby increasing the optical power. If the object is far from the eye, then the lens, on the contrary, stretches and becomes almost flat, and not convex on both sides, due to which the optical power decreases.

In fact, the lens of the eye is similar to an ordinary optical lens that refracts light rays with a certain force. However, unlike a lens, the lens is able to change its curvature and refract rays with different strengths required at a given time, so that the image is focused strictly on the retina, and not closer or behind it.

Accordingly, any change in the shape, size, location, degree of transparency and density of the lens leads to visual impairment of greater or lesser severity.

And a cataract is a clouding of the lens, that is, a loss of transparency due to the formation of a different number of dense and opaque structures in its gel-like subcapsular contents. As a result of a cataract, the lens ceases to transmit a sufficient amount of light rays, and a person ceases to see a clear picture of the world around him. Due to the turbidity of the lens, vision becomes, as it were, "foggy", the outlines of objects become fuzzy and blurry.

The causes of cataracts have not yet been reliably established, but, nevertheless, scientists identify a number of predisposing factors, against the background of which a person develops a cataract. These factors contribute to the development of cataracts, so they are conventionally referred to as the causes of this disease.

At the level of biochemistry, cataracts are caused by the breakdown of proteins that make up the gel-like contents of the lens. Such denatured proteins are deposited in the form of flakes and cloud the lens, which leads to cataracts. But the reasons for the denaturation of lens proteins are very diverse - these can be age-related changes in the body, injuries, chronic inflammatory eye diseases, radiation, metabolic diseases, etc.

The most common predisposing factors for cataracts are the following conditions or diseases:

• hereditary predisposition;
• Age-related changes in the body;
• Endocrine diseases (diabetes mellitus, hypothyroidism, hyperthyroidism, muscular dystrophy, etc.);
• Exhaustion due to starvation, malnutrition, or severe past illnesses (for example, typhoid, malaria, etc.);
• Excessive exposure of the eyes to ultraviolet radiation;
• radiation exposure;
• Poisoning with poisons (mercury, thallium, ergot, naphthalene);
• Skin diseases (scleroderma, eczema, neurodermatitis, poikiloderma Jacobi, etc.);
• Injuries, burns, eye surgery;
• Myopia of a high degree (more than 4 diopters, etc.);
• Severe eye diseases (uveitis, iridocyclitis, retinal detachment, etc.);
• Infections transferred during pregnancy (influenza, rubella, herpes, measles, toxoplasmosis, etc.) - in this case, the newborn may have a congenital cataract;
• Taking glucocorticosteroid drugs (Prednisolone, Dexamethasone, etc.).

Depending on the age of cataract onset, the disease can be congenital or acquired. Congenital cataracts occur even during fetal development, as a result of which the baby is born with a visual defect. Such congenital cataracts do not progress over time and are limited in area.

Acquired cataracts appear during life due to the influence of various causative factors. The most common among the acquired are senile cataracts, due to age-related changes in the body. Other types of acquired cataracts (traumatic, toxic due to poisoning, caused by systemic diseases, etc.) are much less common than senile ones. Unlike congenital, any acquired cataracts progress over time, increase in size, worsening vision more and more, which, ultimately, can lead to complete blindness.

Cataracts are divided into several types, depending on the nature and localization of lens opacities. Determining the type of cataract is important to determine the optimal strategy for its treatment.

Cataract of any kind and localization consistently passes from the moment of appearance 4 stages of maturity- initial, immature, mature and overripe. At the initial stage, the lens becomes hydrated, gaps appear in the gel-like mass that fills it, which violate the transparency of the entire structure. However, since the cracks are located along the periphery, and not in the pupil area, this does not prevent a person from seeing, so he does not notice the development of the disease. Further, at the stage of immature cataract, the number of foci of opacification increases, and they are in the center of the lens opposite the pupil. In this case, the normal passage of light through the lens is already disrupted, as a result of which a person's visual acuity decreases and a feeling of seeing surrounding objects appears as if through fogged glass.

When the opacities fill the entire lens, the cataract becomes mature. At this stage, the person sees very poorly. The pupil with a mature cataract acquires a characteristic white tint. Then comes the stage of overripe cataract, in which the disintegration of the lens substance and the wrinkling of its capsule occurs. At this stage, the person is completely blind.

Cataract progression rate, i.e. passing through all four stages of development, can be different. So, in one person, cataracts can progress very slowly, so that vision remains satisfactory for many years. And in other people, on the contrary, cataracts can progress very quickly and lead to complete blindness literally within 2 to 3 years.

Symptoms of a cataract depending on the stage of the disease may be different. At the first stage, a person does not suffer from visual impairment, but notices often repeated episodes of double vision, flashing "flies" before the eyes, a yellowish color of all surrounding objects, as well as some blurring of the visible picture. Blurred vision is often described by people - "seeing as if in a fog." In connection with the symptoms that have appeared, it becomes difficult to read, write and perform any work with small details.

At the stage of immature and mature cataracts, visual acuity sharply decreases towards myopia, objects begin to blur before the eyes, there is no discrimination of colors, a person sees only blurry contours and outlines. A person no longer sees any small details (people's faces, letters, etc.). By the end of the stage of mature cataract, a person ceases to see anything at all, and only light perception remains.

In addition, at any stage of development, cataracts are characterized by increased photosensitivity, poor vision in the dark, and the appearance of a halo around lighting fixtures when looking at them.

For diagnosing cataracts an ophthalmologist checks visual acuity (visometry), determines the field of view (perimetry), the ability to distinguish colors, measures intraocular pressure, examines the fundus of the eye (ophthalmoscopy), and also makes a detailed study of the lens using a slit lamp (biomicroscopy). In addition, sometimes additional refractometry and ultrasound scanning of the eye can be performed, which are necessary to calculate the optical power of the lens and determine the method of the operation to replace the lens. Based on the results of examinations, the diagnosis of cataract is confirmed or refuted. In cataracts, visual acuity is usually impaired, color discrimination is impaired, and, most importantly, clouding of the lens is visible when examined with a slit lamp.

Cataract treatment may be operative or conservative. If the disease is detected in the initial stages, when vision practically does not suffer, then conservative therapy is carried out aimed at slowing down the progression of cataracts. In addition, conservative therapy is recommended in all cases where a cataract does not prevent a person from engaging in any normal activity. Currently, various eye drops containing vitamins, antioxidants, amino acids and nutrients are used as a means of conservative treatment of the disease (for example, Oftan-Katachrom, Quinax, Vitafacol, Vitaiodurol, Taufon, Taurine, etc.). However, it must be remembered that eye drops are not able to lead to the disappearance of existing opacities in the lens, but can only prevent the appearance of new foci of opacity. Accordingly, eye drops are used to maintain vision at the current level and prevent the progression of cataracts. In many cases, such conservative therapy is very effective and allows a person to live for a long period of time without resorting to surgery.

Surgical treatment of cataracts consists in removing opacities and then installing a special lens in the eye, which, in essence, is like a lens prosthesis. This artificial lens performs the functions of a lens, allows a person to completely and permanently get rid of cataracts and restore vision. Accordingly, the only complete and radical treatment of cataract is surgery.

Currently, ophthalmologists, knowing that surgery is the treatment with the most visible positive result, recommend the removal of opacities and the installation of a lens in almost all cases of cataract. This position of actively promoting the surgical treatment of cataracts is due to the convenience for the doctor, who simply needs to perform a relatively simple operation, after which the patient can be considered cured. But conservative therapy requires effort from both the doctor and the patient, since it is necessary to constantly apply eye drops in courses, undergo examinations and control vision. And yet, despite the advantages of surgery, in many cases, cataracts are preferable to conservative therapy, which stops the progression of the disease.

Causes of cataract

The causes of congenital cataracts are divided into two large groups - these are genetic anomalies and the impact of adverse factors during pregnancy that can disrupt the formation of the lens of the fetal eye.

Genetic anomalies, among the manifestations of which there is a congenital cataract, include the following diseases or conditions:

• Pathologies of carbohydrate metabolism (diabetes mellitus, galactosemia);
• Pathologies of calcium metabolism;
• Pathologies of connective tissue or bones (chondrodystrophy, Marfan syndrome, Weil-Marchesani syndrome, Apert syndrome, Conradi syndrome);
• Skin pathologies (Rothmund's syndrome, Block-Sulzberger's syndrome, Schaefer's syndrome);
• Chromosomal abnormalities (Down syndrome, Shershevsky-Turner syndrome, Marinescu-Sjögren syndrome, Axenfeld syndrome).

• Rubella, toxoplasmosis or cytomegalovirus infection, transferred in the first 12 to 14 weeks of pregnancy;
• The effect of ionizing (radioactive) radiation on the body of a pregnant woman in any period of gestation;
• Rhesus incompatibility of the fetus and mother;
• Fetal hypoxia;
• Lack of vitamins A, E, folic (B 9) and pantothenic (B 5) acids, as well as protein;
• Chronic intoxication of the body of a pregnant woman with various substances (for example, smoking, drinking alcohol, drugs, taking contraceptives or abortion pills).

So, the following diseases or conditions can be the causes of acquired cataract:

• Hereditary predisposition (if parents, grandparents had a cataract, then the risk of its occurrence in a person in old age is very high);
• Female gender (women develop cataracts several times more often than men);
• Age-related changes in the body (slowdown of metabolism, accumulating pathological changes in cells, deterioration of immunity and chronic diseases in combination lead to the formation of opacities in the lens);
• Alcohol, drug use and smoking;
• Endocrine diseases (diabetes mellitus, hypothyroidism, hyperthyroidism, muscular dystrophy, obesity, etc.);
• Chronic autoimmune or inflammatory diseases that worsen the condition of the vessels (for example, rheumatoid arthritis, etc.);
• Exhaustion due to starvation, malnutrition or severe past diseases (for example, typhoid, malaria, etc.);
• Anemia;
• Excessive exposure of the eyes to ultraviolet radiation (stay in the sun without protective glasses);
• Exposure to the eyes of strong thermal radiation (for example, work in a hot shop, frequent visits to hot baths, saunas);
• Exposure to radiation, ionizing radiation or electromagnetic waves on the eyes or the body as a whole;
• Poisoning with poisons (mercury, thallium, ergot, naphthalene, dinitrophenol);
• Down's disease;
• Skin diseases (scleroderma, eczema, neurodermatitis, poikiloderma Jacobi, etc.);
• Injuries, burns, eye surgery;
• Myopia of a high degree (3 degrees);
• Severe eye diseases (uveitis, iridocyclitis, chorioretinitis, Fuchs syndrome, pigmentary degeneration, retinal detachment, glaucoma, etc.);
• Infections transferred during pregnancy (flu, rubella, herpes, measles, toxoplasmosis, etc.) - in this case, the newborn may have a congenital cataract;
• Reception for a long time or in high dosages of glucocorticosteroid drugs (Prednisolone, Dexamethasone, etc.), tetracycline, amiodarone, tricyclic antidepressants;
• Living or working in adverse environmental conditions.

Varieties of cataract

First of all, cataracts are divided into congenital and acquired. Accordingly, congenital cataracts are formed in the fetus during fetal development, as a result of which the baby is born already with an eye pathology. Acquired cataracts develop during a person's life under the influence of predisposing factors. Congenital cataracts do not progress, that is, the number of opacities and their intensity do not increase over time. And any acquired cataracts progress - over time, the number of opacities and the degree of their intensity in the lens increase.

Acquired cataracts are divided into the following types depending on the nature of the causative factor that caused them:

• Age (senile, senile) cataracts developing as a result of age-related changes in the body;
• Traumatic cataracts developing as a result of injury or contusion of the eyeball;
• Radiation cataracts developing as a result of exposure to the eyes of ionizing, radiation, x-ray, infrared radiation or electromagnetic waves;
• Toxic cataracts developing with prolonged use of drugs, smoking, alcohol abuse or poisoning;
• Complicated cataracts developing against the background of other eye diseases (uveitis, iridocyclitis, glaucoma, etc.);
• Cataracts against the background of severe chronic pathologies(for example, diabetes mellitus, thyroid disease, metabolic disorders, dermatitis, etc.);
• Secondary cataracts, developing after one operation to remove a cataract and install an artificial intraocular lens (lens).

Figure 2- Types of cataracts depending on the location and form of opacities.

Congenital cataracts can be represented by any of the above types, and acquired ones are only nuclear, cortical and complete. According to the form of opacities, cataracts can be very diverse - stellate, disc-shaped, bowl-shaped, rosette, etc.

Age-related cataracts, in turn, go through the following stages of development, which are also their types:

• Primary cataract. An excess of fluid appears in the lens, as a result of which water gaps form between the fibers, which are foci of opacities. Opacification usually appears in the peripheral part of the lens, and rarely in the center. Foci of opacities, when viewed inside the pupil in transmitted light, look like spokes in a wheel. At this stage, vision is not significantly affected.
• Immature cataract. Opacification from the peripheral extends to the optical zone of the lens, as a result of which a person's vision deteriorates sharply. The fibers swell, causing the lens to increase in size.
• mature cataract. The entire lens is cloudy, and a person sees practically nothing, but can only distinguish whether it is light or dark indoors or outdoors.
• overripe cataract. There is a breakdown of the fibers and a liquefaction of the lens substance, accompanied by an inflammatory process, which leads to an increase in intraocular pressure and complete blindness. If the substance of the lens is completely liquefied before the removal of this structure, then its nucleus descends, and such a cataract is called Morganian. Sometimes the lens substance liquefies, but the shell remains dense, in which case it shrinks. The operation to remove the lens at this stage is performed only in order to save the eye, since vision during the transition of a cataract to an overripe one, as a rule, is irretrievably lost due to damage to the structures of the eye analyzer by toxic decaying lens structures. An overmature cataract looks like a large (dilated) milky white pupil with numerous white spots. Rarely, an overripe cataract looks like a black pupil due to excessive sclerosis of the lens nucleus.

Cataract diagnostics

• Visometry- determination of visual acuity.
• Perimetry– definition of fields of view.
• Ophthalmoscopy- examination of the fundus.
• Tonometry– measurement of intraocular pressure.
• biomicroscopy– examination of the eye with a slit lamp (it is this method that is decisive for confirming cataracts, since during such an examination the doctor can accurately see the number and shape of opacities in the lens).
• Color testing(aimed at finding out how well a person distinguishes colors - it is very important for the detection of cataracts, since with this disease the ability to distinguish colors deteriorates sharply).
• Refractometry and ophthalmometry are made to determine the linear parameters of the eye - the length of the eyeball, the thickness of the lens and cornea, the radius of curvature of the cornea, the degree of astigmatism, etc. The measured parameters allow the doctor to calculate the characteristics of the artificial lens, which is optimal for a person and can be inserted into the eye during the operation.
• Ultrasound eye scan- is carried out to exclude other diseases of the eye, such as retinal detachment, hemorrhage, destruction of the vitreous body.
• OCT examination(optical coherence tomography) - allows you to determine all the parameters of the eye, identify the type of cataract and the best option for surgical treatment; in addition, OCT examinations can be used for dynamic monitoring of the state of the eye and vision both after surgery and at the stage of preparation for it or during ongoing conservative treatment.

In addition, in some cases, in addition to assessing the state of the retina, optic nerve and visual cortex of the cerebral hemispheres, functional diagnostics are performed using electrooculography (EOG), electroretinography (ERG) and visual evoked potentials (VEP) recording.

Symptoms of a cataract

Clinical picture of a cataract

We will consider the clinical manifestations of each stage of acquired cataracts and the distinctive features of the symptoms of congenital cataracts separately in order to avoid confusion.

Symptoms of acquired cataracts. At the initial stage of a cataract, a person has the following clinical symptoms:

• Diplopia (double vision) in an eye affected by a cataract. To identify this symptom, you need to alternately close your eyes and fix whether there is doubling in any of them. With the progression of the cataract and its transition to the immature stage, doubling in the eye disappears.
• Fuzziness of the visible picture of the surrounding world (see Figure 3). When looking at both close and distant objects, a person sees them as if vaguely, as if looking through fog, a layer of water or misted glass. Glasses and contact lenses do not correct this defect of blurry vision.
• Sensation of running or flashing "flies", spots, stripes and balls before the eyes.
• Glare, flashes and flashes of light before the eyes in a dark room.
• Visual impairment in darkness, twilight, twilight, etc.
• Light sensitivity, in which any light sources appear too bright, hurt the eyes, etc.
• When looking at a light source, a halo is seen around it.
• Difficulty in distinguishing small details such as facial features, letters, etc. As a result, it becomes difficult for a person to write, read, and also perform any activities related to the need to distinguish fine details well (for example, sewing, embroidery, etc.).
• Loss of the ability to distinguish colors, because, firstly, they become very pale, and secondly, they acquire a yellowish tint. It is especially difficult for a person to distinguish between blue and purple colors.
• The need for frequent replacement of glasses or lenses, tk. visual acuity decreases very quickly.
• Temporary improvement in vision, especially if the person had farsightedness before developing cataracts. In this case, he notices that he was suddenly able to see well up close without glasses. But such an improvement is short-lived, it passes quickly, after which there is a sharp deterioration in visual acuity.
• Whitish or grayish spots around the perimeter of the pupil.

With the transition of a cataract from the initial stage to the immature stage, myopia sharply increases in a person. In addition, he sees very poorly any objects located far away (at a distance of 3 meters and further from the eye). Nebula and blurring of the visible picture of the surrounding world, photosensitivity, difficulty in distinguishing small details and inability to distinguish colors increase, but double vision, flickering of “flies”, spots, flashes, and a halo around the light source disappear. The light sensitivity becomes so strong that a person sees better in cloudy weather or at dusk than in daylight or in good artificial light. At the same time, large foci of milky-white cataract spots are clearly visible in the depth of the pupil (see Figure 4). During the entire stage of immature cataract, vision deteriorates, the person sees worse and worse, the ability to distinguish more and more details is lost, and only the vision of blurred outlines of surrounding objects remains.

Figure 4- Pupil in immature cataract.

When a cataract passes into the mature stage, a person loses objective vision, and only light perception remains. That is, a person does not even see the outlines of surrounding objects, his eye is able to distinguish only light or dark at the present moment in the room or on the street. The pupil in the center becomes whitish-gray, and black-violet areas are visible along its edges.

When a cataract passes into the overripe stage, a person becomes completely blind and even loses light perception. At this stage, treatment is absolutely useless, since vision will not be restored. Surgery for overripe cataracts is performed only to save the eye, because. the disintegrating lens masses are toxic to all other eye tissues, which can lead to glaucoma or other serious complications. An overmature cataract is also called a morgania cataract or a milk cataract because the pupil is completely milky white. Sometimes with an overripe cataract, the pupil turns black due to excessive sclerosis of the lens nucleus.

Symptoms of congenital cataracts. With congenital cataracts, the child is still too young to say that he does not see well, so their symptoms are indirect, detected by a doctor or parents. So, the symptoms of congenital cataract in children are as follows:

• The child does not look exactly at people's faces;
• The child does not react to the appearance of people's faces, as well as large or colorful objects in his field of vision;
• The child cannot find small objects, although they are in his field of vision;
• In bright sunlight or artificial light, the child looks askance, sideways, or covers his eyes;
• Nystagmus (repeated wandering movements of the eyes);
• In the photographs of the child, he does not have a "red eye".

lens for cataract

Further, in the second, immature stage due to the stratification of the fibers, a sufficient amount of nutrients does not penetrate into them, as a result of which the proteins of the structural components of the lens break down. The decayed proteins cannot be removed anywhere, since the lens is covered with a capsule, as a result of which they are deposited in the previously formed gaps between the fibers. Such deposits of decomposed proteins are clouding of the lens. At this stage, the lens increases in size and can provoke an attack of glaucoma due to a violation of the outflow of intraocular fluid.

In the third stage of mature cataract all the proteins of the lens gradually disintegrate, and it turns out to be all occupied by turbid masses.

Stage 4 overripe cataract the cortical substance of the lens disintegrates, as a result of which its dense nucleus is separated from the capsule and falls to the back wall. The entire lens is wrinkled. The process of disintegration of the cortical substance is accompanied by inflammation, as a result of which a rupture of the lens membrane and the release of necrotic masses into the chambers of the eye are possible. And since the masses of the decaying cortical substance are toxic, the development of complications in the form of iridocyclitis, glaucoma, etc. is possible. The lens at the fourth stage of cataract is recommended to be urgently removed in order to avoid possible complications and at least save the eye, albeit completely blind.

Vision with cataracts

Objects located far away (3 meters and further from the eye), a person sees poorly, and those objects that are close cannot be seen due to the blurring of the picture. Blurred vision is not corrected with glasses or lenses.

In addition, when looking at light sources, a person sees a halo around them, so it is difficult for him to drive a car in the dark or walk along a street lit by lanterns, as the glare from llamas leads him astray. In addition to the specific vision of light sources, photophobia appears with cataracts, when any normal lighting (solar or artificial) seems too bright and irritating to the eyes. Because of photophobia, paradoxically, a person sees better on cloudy days or at dusk, and not in sunny clear weather.

With a cataract, it is very difficult for a person to distinguish colors because they become pale, especially blue, indigo and purple. In addition, all colors acquire a certain yellowish tint. The colored world becomes, as it were, pale, fuzzy.

Also, with a cataract, a person is worried about double vision, constantly flashing flashes and flashes of light before the eyes in the dark.

If a person was farsighted before the onset of cataracts, he may find that he is suddenly able to see well up close and even read without glasses. This short-term improvement in vision is due to the fact that a cataract changes visual acuity towards myopia. But as the disease progresses, myopia will increase, and the acquired ability to read without glasses will disappear.

Cataract - what is it? Symptoms and signs. Surgery to install an artificial lens - video

Complications

• obscurative amblyopia - consists in atrophy of the retina with complete loss of vision (this complication is typical for congenital cataracts);
• Dislocation lens- displacement of the lens into the chamber of the eye with separation from the ligament holding it;
• Blindness - loss of vision with the impossibility of its restoration by any known methods of therapy;
• Phacogenic glaucoma- a sharp increase in intraocular pressure due to a violation of the outflow of intraocular fluid due to an increase in the size of the lens;
• Phacolytic iridocyclitis- inflammation of the iris and ciliary body, which can lead to a significant deterioration in vision.

Cataract of the eye: definition, causes, signs and symptoms, diagnosis and treatment, surgery (opinion of an ophthalmologist) - video

lens - This is one of the main organs of the optical system of the organ of vision (eye). Its main function is the ability to refract the flow of natural or artificial light and evenly apply it to the retina.

This element of the eye is small in size (5 mm thick and 7-9 mm high), its refractive power can reach 20-23 diopters.

The structure of the lens is similar biconvex lens , the front side of which is somewhat flattened, and the back is more convex.

The body of this organ is located in the posterior eye chamber, the fixation of the tissue bag with the lens is regulated by the ligamentous apparatus of the ciliary body, such attachment ensures its static, accommodation and correct location on the visual axis.

An important property of the lens is its transparency, it is provided by special protein enzymes at the cellular level. As a result of diseases or natural aging, the biological lens of the eye can become cloudy and lose its optical properties. In such cases, doctors may recommend replacing the affected lens with an artificial one. Modern products of this kind have all the necessary visual characteristics.

Cataract

The main reason for the change in the optical properties of the lens is age.

Violations of the normal blood supply, the loss of capillaries of their elasticity and tone lead to changes in the cells of the visual apparatus, its nutrition deteriorates, the development of dystrophic and atrophic processes is observed.

In most diseases, changes in it are progressive in nature, and ophthalmic, special, diet, and only for a while “slow down” the development of pathological changes. Therefore, often patients with severe lens opacity are faced with the choice of an operative method of treatment.

Progressive techniques of eye microsurgery make it possible to replace the affected lens with intraocular lens (a lens created by the minds and hands of man).

This product is quite reliable and has received positive feedback from patients with affected lens. They are based on the high refractive properties of an artificial lens, which have allowed many people to regain visual acuity and their usual way of life.

There are a lot of models of medical lenses. To date, intraocular lenses allow the treatment of comorbidities, i.e. myopia, farsightedness, astigmatism.

Which lens is better - imported or domestic - it is impossible to answer in monosyllables. In most ophthalmological clinics, during operations, standard lenses from manufacturers in Germany, Belgium, Switzerland, Russia, and the USA are used. All artificial lenses are used in medicine only as licensed and certified options that have passed all the necessary research and testing. But even among high-quality products of this kind, the surgeon's opinion plays a decisive role in their selection. Only a specialist can determine the appropriate optical power of the lenses and its correspondence to the anatomical structure of the patient's eye.

Operation cost

How much it costs to replace the lens depends on the quality of the artificial lens itself. The fact is that the compulsory health insurance program includes rigid versions of the artificial lens, and for their implantation, deeper and wider surgical incisions are required.

Artificial lens installed during the operation (photo)

Therefore, most patients, as a rule, choose lenses that are included in the paid list of services (elastic), this determines the cost of the operation, which includes:

• the price of an artificial lens (from 25 to 150 thousand rubles);
• services of specialists (often free of charge);
• diagnostic examinations, food and accommodation in a hospital (at the request of the patient, it can be carried out in a budgetary institution or a private clinic).

In each region for cataracts, the cost of placing an artificial lens may be determined based on state programs, federal or regional quotas.

Some insurance companies pay for the purchase of an artificial lens and the operation to replace it. Therefore, when contacting any clinic or public hospital, it is necessary to familiarize yourself with the procedure for providing medical procedures and surgical interventions.

Replacement

Today, lens replacement for cataracts, glaucoma or other diseases is an ultrasonic femtosecond laser phacoemulsification procedure.

The clouded lens is removed through a microscopic incision and an artificial lens is placed. This method minimizes the risk of complications (inflammation, damage to the optic nerve, bleeding).

The operation lasts for uncomplicated eye diseases about 10-15 minutes, in complex cases more than 2 hours.

Preliminary preparation requires:

• selection of artificial lenses,which lens is best for the patient will be recommended by the attending physician based on the examination and data from instrumental studies;
• blood tests (sugar, clotting, biochemical parameters), urine (leukocytes, protein);
• examination by a therapist, dentist, cardiologist, ENT doctor, endocrinologist;
• undergoing fluoroscopy.

The course of the operation includes:

• instillation of drops that dilate the pupil;
• conducting local anesthesia;
• eye piercing;
• removal of the affected lens;
• insertion of a folded soft artificial lens and its self-expansion inside the eye;
• washing the mucosa with antiseptic solutions.

The postoperative period takes about 3 days, and if the surgical intervention was performed on an outpatient basis, then the patients are immediately released home.

With a successful lens replacement, people return to their normal lifestyle. after 3-5 hours . The first two weeks after it, some restrictions are recommended:

• reduced visual and physical activity;
• inflammatory complications are prevented with special drops.

With a successful outcome of the operation, the patient will be able to see within 2-3 hours after the operation. Subject to all preventive measures, complete restoration of visual functions occurs 1-2 months after the placement of an artificial lens.

Video:

The human eye is a complex optical system whose task is to transmit the correct image to the optic nerve. The components of the organ of vision are the fibrous, vascular, retinal membranes and internal structures.

The fibrous membrane is the cornea and sclera. Through the cornea refracted enter the organ of vision. The opaque sclera acts as a framework and has protective functions.

Through the choroid, the eyes are fed with blood, which contains nutrients and oxygen.

Under the cornea is the iris, which provides the color of the human eye. In the center of it is a pupil that can change size depending on the lighting. Between the cornea and is intraocular fluid, which protects the cornea from microbes.

The next part of the choroid is called due to which the intraocular fluid is produced. The choroid is in direct contact with the retina and provides it with energy.

The retina is made up of several layers of nerve cells. Thanks to this organ, the perception of light and the formation of an image are ensured. After that, information is transmitted through the optic nerve to the brain.

The inner part of the organ of vision consists of the anterior and posterior chambers filled with transparent intraocular fluid, the lens and the vitreous body. has a jelly-like appearance.

An important component of the human visual system is the lens. The function of the lens is to ensure the dynamism of the eye optics. It helps to see different objects equally well. Already at the 4th week of embryo development, the lens begins to form. The structure and functions, as well as the principle of operation and possible diseases, we will consider it in this article.

Structure

This organ is similar to a biconvex lens, the anterior and posterior surfaces of which have different curvatures. The central part of each of them is the poles, which are connected by an axis. The axle length is approximately 3.5-4.5 mm. Both surfaces are connected along a contour called the equator. An adult has an optical lens size of 9-10 mm, a transparent capsule (anterior bag) covers it on top, inside which there is a layer of epithelium. The posterior capsule is located on the opposite side; it does not have such a layer.

The possibility of growth of the eye lens is provided by epithelial cells, which are constantly multiplying. Nerve endings, blood vessels, lymphoid tissue in the lens are absent, it is entirely an epithelial formation. The transparency of this organ is affected by the chemical composition of the intraocular fluid, if this composition changes, clouding of the lens is possible.

The composition of the lens

The composition of this organ is as follows - 65% water, 30% protein, 5% lipids, vitamins, various inorganic substances and their compounds, as well as enzymes. The main protein is crystallin.

Principle of operation

The lens of the eye is the anatomical structure of the anterior segment of the eye, normally it should be perfectly transparent. The principle of operation of the lens is to focus the rays of light reflected from the object into the macular zone of the retina. In order for the image on the retina to be clear, it must be transparent. When light hits the retina, an electrical impulse occurs, which travels through the optic nerve to the visual center of the brain. The job of the brain is to interpret what the eyes see.

The role of the lens in the functioning of the human vision system is very important. First of all, it has a light-conducting function, that is, it ensures the passage of the light flux to the retina. The light-conducting functions of the lens are provided by its transparency.

In addition, this organ takes an active part in the refraction of the light flux and has an optical power of about 19 diopters. Thanks to the lens, the functioning of the accommodative mechanism is ensured, with the help of which the focusing of the visible image is spontaneously adjusted.

This organ helps us to easily shift our gaze from distant objects to those that are close, which is ensured by a change in the refractive power of the eyeball. With the contraction of the fibers of the muscle that surrounds the lens, there is a decrease in the tension of the capsule and a change in the shape of this optical lens of the eye. It becomes more convex, due to which nearby objects are clearly visible. When the muscle relaxes, the lens flattens out, allowing you to see distant objects.

In addition, the lens is a partition dividing the eye into two sections, which ensures the protection of the anterior sections of the eyeball from excessive pressure of the vitreous body. It is also an obstacle to microorganisms that do not enter the vitreous body. This is the protective function of the lens.

Diseases

The causes of diseases of the optical lens of the eye can be very diverse. These are violations of its formation and development, and changes in location and color that occur with age or as a result of injuries. There is also an abnormal development of the lens, which affects its shape and color.

Often there is a pathology such as cataracts, or clouding of the lens. Depending on the location of the turbidity zone, there are anterior, layered, nuclear, posterior and other forms of the disease. Cataracts can be either congenital or acquired during life as a result of trauma, age-related changes, and a number of other reasons.

Sometimes injuries and breakage of the threads that keep the lens in the correct position can cause it to move. With a complete rupture of the threads, a dislocation of the lens occurs, a partial rupture leads to subluxation.

Symptoms of damage to the lens

With age, visual acuity of a person decreases, it becomes much more difficult to read at close range. The slowdown in metabolism leads to changes in the optical properties of the lens, which becomes denser and less transparent. The human eye begins to see objects with less contrast, the image often loses color. When more pronounced opacities develop, visual acuity is significantly reduced, cataracts occur. The location of the opacity affects the degree and speed of vision loss.

Age-related turbidity develops for a long time, up to several years. Because of this, impaired vision in one eye can go unnoticed for a long time. But even at home, you can determine the presence of cataracts. To do this, you need to look at a blank sheet of paper with one, then with the other eye. In the presence of the disease, it will seem that the leaf is dull and has a yellowish tint. People with this pathology need bright lighting in which they can see clearly.

Opacification of the lens can be caused by the presence of an inflammatory process (iridocyclitis) or long-term use of drugs that contain steroid hormones. Various studies have confirmed that clouding of the optical lens of the eye occurs faster in glaucoma.

Diagnostics

Diagnosis consists of checking visual acuity and examination with a special optical device. The ophthalmologist evaluates the size and structure of the lens, determines the degree of its transparency, the presence and localization of opacities that lead to a decrease in visual acuity. When examining the lens, the method of lateral focal illumination is used, in which its front surface, located within the pupil, is examined. If there are no opacities, the lens is not visible. In addition, there are other research methods - examination in transmitted light, examination with a slit lamp (biomicroscopy).

How to treat?

Treatment is mainly surgical. Pharmacy chains offer various drops, but they are not able to restore the transparency of the lens, and also do not guarantee the cessation of the development of the disease. Surgery is the only procedure that ensures complete recovery. Extracapsular extraction with suturing of the cornea can be used to remove cataracts. There is another method - phacoemulsification with minimal self-sealing incisions. The removal method is chosen depending on the density of opacities and on the state of the ligamentous apparatus. Equally important is the experience of the doctor.

Since the eye lens plays an important role in the operation of the human vision system, various injuries and violations of its work often lead to irreparable consequences. The slightest sign of visual impairment or discomfort in the eye area is a reason for an immediate visit to a doctor who will diagnose and prescribe the necessary treatment.

An artificial lens of the eye or an intraocular lens is an implant that is placed in place of a previously removed natural lens if the latter has lost its function.

Unlike glasses and lenses, the IOL is able to correct significant visual aberrations, including nearsightedness, farsightedness, and a high degree of astigmatism. Placed in the eye, an artificial lens performs all the tasks of a natural lens, which allows you to provide the required vision characteristics in full.

In what cases is it necessary to replace with artificial

The main indication for replacing the natural lens with an artificial one is clouding of this area. The natural eye lens loses its transparency, which is why there is a decrease in visual acuity up to. This process is called a cataract.

Pathology develops under the influence of a number of factors:

• In old age;
• With diabetes;
• With radiation exposure;
• After an eye injury;
• as a hereditary pathology.

On the video - an artificial lens of the eye:

The disease causes at first only a blurry image. It becomes hazy and forked. The perception of color begins to be disturbed, photophobia appears. When these symptoms appear, the doctor decides whether it is necessary to remove the natural lens and replace it with an IOL. Drug treatment in such cases does not help, but it allows you to slow down the development of pathology. All that remains is an operation to replace this element of the organ of vision.

It is not worth waiting until complete blindness, otherwise the operation no longer helps and the person loses his sight irreversibly.

But how is the treatment of secondary cataract after lens replacement, will help to understand this

Based on the foregoing, we can conclude that this implant is used only in serious conditions that threaten with loss of vision. Accordingly, an intraocular lens is used in the treatment of:

• cataracts. But how it happens, the information on the link will help to understand;
• myopia;
• farsightedness;
• Astigmatism.

The last three points are decisive in deciding whether to perform surgical procedures only in the case when there is a high degree of damage.

What does the artificial lens of the eye look like, service life

The artificial lens includes two elements:

• Optic;
• Reference.

Supporting artificial lens of the eye

The optical part is a lens made of a transparent flexible material that is compatible with the tissues of the eyeball. On the surface of the optical section of the IOL, there is a special diffraction zone that allows you to get a clear image.

Useful information on the topic! How it manifests itself, what is the danger of such a deviation, what methods of treatment exist.

The supporting element helps to securely fix the implant in the capsule, where the natural human lens was located. During the operation, the flexibility of the material plays an important role. This makes it possible to introduce an instrument with a compressed lens into the capsule area through a micro-incision with a diameter of no more than 1.8 mm and place it there.

It quickly straightens and independently fixes in the place of manipulation. The product does not have an expiration date and its functioning is designed for many years with the correct implementation of all surgical procedures and the choice of a specific implant with optical characteristics corresponding to a particular case.

But what should be the rehabilitation after cataract surgery to replace the lens, you can find out

Kinds

There are several types of IOLs that have their own advantages and disadvantages.

In general, in the modern market of ophthalmic surgery and implantation stand out:

toric lens

The monofocal element is most commonly used in cataract surgery. It gives excellent distance vision function in different degrees of illumination. But near vision may require minor additional correction with glasses (when reading, watching TV, and so on). If the patient is ready to use glasses to correct the function of vision after IOL implantation, this option is considered the most optimal. And here's what to do. when a black dot appeared in the eye, detailed

Often, after IOL vision correction, many complain about the need for additional correction. With certain implants, this factor is inevitable and cannot be avoided.

But why clouding of the lens of the eye occurs and what can be done with such a problem, you can read in this

The accommodating monofocal lens allows you to get an excellent degree of vision both far and near. This IOL can change its position in the eye so that the object is focused on the retina at any degree of distance from the object. That is, this lens is able to imitate the normal accommodation of a young lens.

The only representative of this type of IOL is the CRISTALENS IOL lens, which is manufactured in the USA. In Russia, this element has not yet been tested. All patients who have been introduced such a lens do not need additional correction glasses when reading. This option is considered the most successful for those people who sit at the computer a lot or read.

The multifocal lens is the latest in cataract surgery. This type of product makes it possible to achieve perfect vision at any distance without the use of additional accessories - glasses or contact lenses.

Specifically, this implant has all the necessary optical characteristics, which are characterized by ultra-precision, projecting an image to different points at the same time. In terms of action, only multifocal glasses can be compared with them. Three types of such products are used in the West. If the ophthalmologist is experienced, then he easily selects the required type of product after appropriate research.

The choice of lenses should be made with a doctor. In this case, preference should be given to high-quality lenses, because their service life is unlimited, and therefore they should serve until the end of their lives.

You may also find it helpful to learn more about what an artificial eye lens looks like and how

The spherical lens improves distance vision. It will also provide excellent vision in the central part. The disadvantage of this implant is the presence of some discomfort after the operation. Vision at first is distorted, but over time this effect disappears.

An aspherical lens is used when visual function deteriorates due to the natural aging process. It usually manifests itself as a gradual decrease in visual acuity, as well as deterioration in near vision. Not so long ago, these lenses were developed with a special structure that allows you to perform all the necessary functions of a young natural lens. This increases not only visual acuity, but also contrast sensitivity. To put it simply, the patient begins to see as in his youth. These lenses have not been tested in Russia, but they are successfully used abroad.

Toric IOLs are usually used in patients with high astigmatism (starting at 1.5 D). When compared with aspherical, toric ones are able to correct not only postoperative, but also corneal. Corneal or physiological astigmatism develops with age. In such cases, it is not possible to choose the right glasses. an artificial lens of this type helps, due to the presence of a complex surface, to correct the curvature of the cornea, relieving both astigmatism and cataracts in one operation. But how it happens, you can find out from the article at the link.

Is it possible to repeat the operation to replace

Most doctors do not replace the lens again, since incorrect vision some time after the operation is most often caused not by the quality of the implant, but by the presence of problems in other parts of the eye or other defects. This condition is corrected either with glasses or with the help of laser correction. The reason can be revealed only during a full examination. But what are the glasses for strabismus in adults and how to use them correctly for the best result, it is indicated

Replacement of the lens can be made according to indications, if the initial one did not fit for one reason or another. In other cases, doctors try to correct vision with more gentle methods.

On the video - how to choose the right lens:

Manufacturers and prices

Many companies produce artificial lenses for the eyes. The best are foreign companies located in the United States. Also, German IOLs are not inferior in quality. Here are the main representatives of these implants:

The cost varies depending on the type and characteristics of the item. Your doctor will help you choose the best option. As can be seen from the table, Alcon lenses, which are manufactured in the USA, have the largest price range. They are considered one of the highest quality.

However, we have much to be proud of! And even if we do not see ultraviolet rays at all, we are poorly oriented in the dark, but, you see, the world is beautiful for us even without it!

And in general, it is normal for people to see everything in three dimensions, so it is difficult for us to imagine that someone can see the world in a different way. But, believe me, this is how, in a different way, not in volume, most animals see the world.

By the way, it is very easy to determine whether this or that animal sees in three dimensions or not: just look at how its eyes are located. If they are parallel, on both sides of the head, like a horse, dove or lizard, then the animal does not see in three dimensions. Conversely, if the eyes are located on the front side of the head, as in humans, monkeys and cats, you can be sure that this organism sees in volume.
The presence of two eyes allows us to make our vision stereoscopic, i.e. get a 3D image.

The right eye transmits the "right side" of the image to the right side of the brain, and so does the left eye. As a result, these two parts of the image - the right and the left, our brain connects together. But, since each eye perceives "its own" picture, if their joint movement is disturbed, a person will begin to double in his eyes or he will simultaneously see two completely different pictures, in fact, this happens when intoxicated.

In animals whose eyes are located on opposite sides of the head, the two pictures do not overlap, and they do not see in volume.

For example, a horse's eyes are located exactly parallel to the sides of the head, which means that she does not see in volume, but on the other hand, she can, without turning her head, see what is happening on the side and even behind, because her "visual field" is huge, and eating grass does not need an accurate assessment of the distance - you can poke your face ....

But, the cat's eyes are in front, they have three-dimensional vision, because cats are hunters and such vision is very necessary for them and allows them to accurately determine the distance for the decisive jump during the hunt. But since in nature there are much more herbivores than carnivores, the number of animals that see in three dimensions, to put it mildly, is small.

And the most sharp-eyed and sharp-sighted of all animals are birds of prey. On the one hand, their eyes are located on both sides of the head, and on the other hand, they are round, bulging and protrude forward. Therefore, birds see everything that happens both in front and from the side, and even with such accuracy ...... For example, a falcon, an eagle or a kite from a height of the twentieth floor could read a newspaper lying on the ground, if they could read, of course :) .

Well, I hope you are already interested in the device of an optical device called eyes? Then let's "see" how it all works.

In general, the principle of our eye is copied in digital video cameras.

Like a video camera, the eye has a lens. It consists of two lenses: the first - cornea - a transparent convex plate inserted into the dense shell of the eye ( sclera) like a watch glass. And in order to prevent scratching of the cornea by small particles such as sand, dust and smoke, the cornea is closed conjunctiva(the mucous membrane of the eye), for greater reliability, is constantly wetted with tears, and is additionally protected by eyelashes and eyelids.

The second lens lens, biconvex. Unlike a video camera, the lens is made of an elastic material, and its surface, with the help of a circular ciliary muscle, can change their curvature, i.e. become flatter or vice versa convex.
This allows us to keep the image in focus, i.e. sharpen when changing the distance to the subject. Video cameras have exactly the same feature, only it is carried out not by changing the curvature of the lenses, but by moving them forward or backward.

The next common element between the eye and the video camera is the diaphragm. In our eye it is called pupil, which is nothing but a simple hole in iris. The iris consists of muscles, with the contraction and relaxation of which the size of the pupil changes, which means that the amount of light passing through the pupil and lens also changes. That is why the pupils are dilated in the dark, and constricted in the light.

In addition, the iris is also responsible for the color of the eyes, because it contains pigment cells. If this pigment is small, the eyes are light, and if there is a lot, then they are almost black.

By the way, all newborn babies have eyes. always blue and only then, as the pigment accumulates, they take on the color laid down by nature and parents.

Unlike a video camera, our eye is not filled with air, but with a liquid: the space between the cornea and the lens ( anterior chamber of the eye) is filled with a special chamber moisture, and the space behind the lens is filled with a gelatinous, but perfectly transparent mass - vitreous body.

Rays of light focused by the optical system of the eye or video camera are ultimately projected onto a special screen. The camera has a bunch of tiny photocells that convert the light signal into an electrical signal, and the eye has a special shell - retina.