LECTURE No. 27. Cataract

Cataract - partial or complete clouding of the substance or capsule of the lens with a decrease in visual acuity up to its complete loss. There are primary and secondary cataracts, acquired and congenital. Congenital cataracts can be hereditary or result from intrauterine developmental disorders, such as infections in the mother, such as rubella, etc.

Etiopathogenesis and pathological anatomy. Depending on the etiological factor, several groups of cataracts are distinguished: senile, traumatic, complicated, radiation, toxic and metabolic.

The mechanism of development of age-related cataracts is multifactorial and is not yet fully understood. With age, the mass and thickness of the lens increase, and its refractive power decreases. The nucleus of the lens is compressed by new layers of fibers forming concentrically and becomes harder. As a result, the transparency of the lens is sharply reduced. Chemically altered core proteins gradually stain. With age, the lens takes on shades from yellow to brown.

A blunt, non-penetrating wound can cause clouding of the lens, affecting part or all of it. The initial manifestation of a contusion cataract is often a stellate or rosette-like opacification, usually located in the center of the lens, where the back of the lens is involved. Rosette-shaped cataracts can progress to complete opacification. In some cases, the lens capsule ruptures with blunt trauma, followed by swelling of the lens fibers, resulting in clouding of the lens.

Complicated cataracts often form against the background of chronic uveitis of various origins due to the toxic effects of inflammatory products on the lens.

The lens is very sensitive to radiation: infrared radiation, which causes damage to the anterior capsule of the lens in the form of peeling of the surface layers, ultraviolet radiation (290-329 nm), ionizing radiation.

As a result of exposure to a number of chemicals (naphthalene, dinitrophenol, thallium, mercury, ergot), toxic cataracts develop. The ingress of alkali into the conjunctival cavity causes damage to the conjunctiva, cornea and iris and often leads to the development of cataracts. Alkaline compounds easily penetrate the eye, reduce the acidity of chamber moisture and reduce the level of glucose in it.

Cataract occurs in some metabolic diseases: diabetes mellitus, galactosemia, hypocalcemia, Westphal-Wilson-Konovalov's disease, myotonic dystrophy, protein starvation.

In diabetes mellitus, with an increase in blood sugar levels, the glucose content in the chamber humor and lens increases. Water then enters the lens, causing the lens fibers to swell. Edema affects the refractive power of the lens. In 75% of patients with classic galactosemia, cataracts usually develop during the first weeks after birth. The accumulation of galactose inside the lens leads to an increase in intracellular pressure, fluid enters the nucleus of the lens, and the layers of the cortex take on the appearance of “oil drops” visible in transmitted light. Cataracts can form in any condition that leads to a decrease in calcium levels in the blood: tetany, spasmophilia, rickets, renal failure. In Westphal Wilson-Konovalov disease, copper metabolism is impaired. A golden-brown Kaiser-Fleischner ring appears, which is formed by pigment granules. The ring is separated from the corner of the eye by a strip of transparent corneal tissue. With miotic dystrophy, patients develop multicolored iridescent crystals in the posterior intracapsular layers of the lens. The disease is hereditary.

Pathoanatomical changes in cataracts are manifested depending on the location, type and degree of clouding of the lens. The following types of cataracts are distinguished: polar, suture, nuclear, capsular, zonular, complete, membranous.

With polar cataracts, changes in the lens form in the intracapsular layers of the anterior or posterior pole of the capsule. Suture cataracts are manifested by opacification of the Y-shaped suture of the nucleus. Congenital nuclear cataract is an opacification of any embryonic nucleus. Capsular cataract is a limited opacification of the epithelium and anterior capsule of the lens. Zonal cataract is a bilateral symmetrical lesion. A complete cataract is a clouding of all lens fibers. Membranous cataract occurs when the proteins of the lens are reabsorbed. In this case, the anterior and posterior capsules of the lens are fused into a hard membrane.

clinical picture. The clinical picture of cataract in the primary form is manifested by complaints of decreased visual acuity. Sometimes the first symptoms of cataract are distortion of objects, monocular polyopia (multiple vision of objects).

In the clinical course of senile cataracts, initial, immature, mature and overmature stages are distinguished. In the initial stage, patients may have no complaints, others note a decrease in visual acuity, the appearance of “flying spots”, and sometimes polyopia. During a biochemical study at this stage, the appearance of intracapsular bubbles and separation of the lens fibers are determined. After 23 years, the stage of immature cataract begins. At this stage, the phenomena of hydration of the lens increase, and patients complain of a sharp decrease in vision. The immature cataract stage lasts for years. Gradually, the lens begins to lose water, and the clouding acquires an intense gray tint and becomes uniform. The stage of mature cataract occurs. At this stage, the figure of a lens star and intense opacification in the area of ​​the lens sutures are visible. Patients complain of a lack of objective vision. With overripe cataracts, the cortex transforms into a liquefied milky mass, which undergoes resorption, and the volume of the lens decreases.

With nuclear cataracts, central vision is impaired early, and distant vision is more affected. Temporary myopia may occur. In side light, the lens in these cases has a light green tint.

Complications of cataracts are phacolytic glaucoma, phacogenous iridocyclitis. Phacolytic glaucoma develops in immature cataracts due to the absorption of a decaying substance during swelling of the lens, an increase in its volume and as a result of a violation of the outflow of intraocular fluid. When cataract masses fall into the anterior chamber of the eye and their resorption is delayed, iridocyclitis may occur, associated with the development of hypersensitivity to the lens protein.

Treatment. Conservative cataract therapy is used for initial lens opacification to prevent its progression. Medicines used to treat cataracts contain a means for correcting metabolic processes, normalizing electrolyte metabolism, redox processes and reducing lens edema (oftankatachrome, soncatalin, vitaiodurol, quinax).

Surgical treatment (removal of the cataract) remains the main treatment for lens opacity. Indications for surgical treatment are set individually. It depends on the state of visual functions, the nature and intensity of the clouding of the lens. Removal can be intracapsular or extracapsular. With intracapsular removal, the lens is removed in a capsule. With extracapsular removal, after opening the anterior capsule of the lens, the nucleus is squeezed out, and the lens masses are sucked off. A method has been developed for removing cataracts through tunnel incisions, which are sutured. Currently, the main methods of cataract removal in children include suction, ultrasonic phacoemulsification and mechanical removal of the lens.

1. Cataracts in children

In accordance with the classification proposed by E. I. Kovalevsky in 1970, the following forms of cataracts in children should be distinguished.

By origin, they are divided into: congenital (hereditary, intrauterine); consistent due to local processes (uveitis, congenital glaucoma, injuries, etc.) and due to general diseases (infectious and neuroendocrine diseases, radiation sickness, metabolic diseases, etc.); secondary (postoperative).

By localization, cataracts are: polar, nuclear, zonular, coronary, diffuse, membranous, polymorphic, anterior and posterior (cup-shaped, rosette).

According to the absence or presence of complications and concomitant changes, cataracts are divided into: simple (except for opacities, there are no other changes), with complications (nystagmus, amblyopia, strabismus), with concomitant changes (congenital malformations of the eye, microphthalmos, aniridia, coloboma of the vascular tract, retina, optic nerve, etc., acquired by pathology of posterior and anterior synechiae, subluxation and dislocation of the lens, vitreous hernia).

According to the degree of visual impairment: the first degree of cataract visual acuity is 0,3 and above), the second is 0,20,05, the third is below 0,05.

2. Congenital cataracts (cataractae congenitae)

Anterior and posterior polar cataracts (cataractae polaris anterior et posterior) are diagnosed by their location at the poles of the lens. Opacities are clearly visible in transmitted light and biomicroscopy. Anterior polar cataracts can also be detected on examination with lateral illumination. Polar cataract has the appearance of a dense white disk with a diameter of not more than 2 mm, quite clearly delimited from the surrounding transparent areas of the lens. When the eyeball moves, the anterior polar cataract is viewed in transmitted light moving in the direction of eye movement, while the posterior polar cataract moves in the opposite direction. These types of cataracts usually do not affect visual acuity and are not subject to surgical treatment.

Zonular (layered) cataract (cataracta zonularis) is the most common congenital pathology of the lens. In transmitted light, a zonular cataract is a gray, lighter in the center disk 56 mm in diameter with radiar processes ("riders") against the background of a pink reflex of the fundus.

In the light of a slit lamp, clouding is visible in the form of a disk located in the central sections and surrounded by a transparent substance of the lens. Along the edge of the disk, which consists of separate opacification zones, additional opacities in the form of protrusions are visible. The degree of vision loss depends on the intensity of the clouding.

Unlike other types of congenital opacities, zonular cataract can progress in the first years of a child's life.

Diffuse (complete) cataracts (cataracta diffusa) are visible even with side lighting. The pupil area is diffusely gray, vision is sharply reduced.

One of the varieties of congenital cataracts is membranous cataract (cataracta membranacea), which has a gray (white), often homogeneous color. This type of cataract is diagnosed according to the biomicroscopic picture (deeper anterior chamber, iridodonesis, direct optical section of the lens) and echography data (one echopic from the lens instead of two). Such cataracts also significantly reduce visual acuity and, like diffuse ones, are subject to removal.

All rare lens opacities (coral-shaped, pyramidal, etc.) of congenital genesis of various localization and severity, on which the degree of vision loss depends, are taken for polymorphic cataract.

3. Diagnosis of cataracts in children

When examining a child, it is important to find out how the mother’s pregnancy proceeded, whether there were any harmful effects on her body (rubella, influenza, chicken pox, oxygen starvation of the fetus as a result of heart disease in the mother, lack of vitamin A in the pregnant woman’s diet, etc. ), at what weight and whether the child was born full-term, and whether he was kept in an oxygen tent after birth. Find out the presence in the anamnesis of general (tuberculosis, diabetes, infectarthritis, etc.) and local (uveitis, trauma, etc.) processes that can cause the occurrence of sequential cataracts.

An examination of the eye is always preceded by a brief acquaintance and establishment of contact with the child, then visual functions are determined. In young children, when it is not possible to determine vision by classical methods, one should pay attention to how they orient themselves in the environment, whether they have shaped vision (whether they reach for a toy that is shown at various distances from the eye, whether they move freely) . Visual acuity in older children and adults should be determined according to the tables (up to two units) with both narrow and wide pupils, with and without correction, since this is important in clarifying the indications and choosing the method of surgical intervention. If the patient has light projection, it should be established whether it is correct. If the projection of light on the eye with a cataract is incorrect and it is impossible to examine the deeper parts of the eye (vitreous body, retina, optic nerve, choroid) using visual methods, echo-ophthalography is performed, which allows to detect changes in the vitreous body, retinal detachment, etc.

The study of the visual field in patients with cataracts can be carried out on the projection-registration perimeter with an object of the greatest brightness and magnitude, as well as on the desktop perimeter with a luminous object or a candle. Approximately the field of view is also determined in the process of studying the light projection.

You should not immediately resort to forcible examination of the child (with the help of eyelid lifters). During an external examination, attention is paid to the position and excursion of the eyeballs (in case of strabismus, the magnitude of the Hirschberg deviation is determined), the presence of nystagmus and other complications, as well as concomitant congenital anomalies.

Further, under conditions of mydriasis (caused by 0,10,25% scopolamine, 1% homatropine, etc.), an examination is carried out with a side lamp, a combined method and in transmitted light. During an eye examination, young children are occupied by showing bright toys and talking. When examining the eyes, you can see clouding of the lens in the form of a gray disk (zonular cataract) or a gray dot (anterior polar cataract), etc. You should pay attention to which direction the clouding shifts when the eye moves. This allows us to judge their topography in the lens. When the lens is subluxated (dislocated), its edge is visible; also, with dislocation, changes in the depth of the anterior chamber, trembling of the iris (iridodonesis), congestive injection of the eye are noticeable, and increased ophthalmotonus can be detected by palpation. In the absence of opacities in the lens, its pathology can be indirectly judged by visual acuity and accommodative ability.

When examining the cornea, scars can be detected, indicating a perforated wound in the past and the traumatic origin of the cataract, as well as a former surgical intervention. Particular attention is paid to the depth and uniformity of the anterior chamber. A deep and sometimes uneven chamber occurs with aphakia, dislocations of the lens, and iridodonesis (trembling of the iris) is often observed during eye movement.

Posterior synechia, subatrophy of the iris, expressed in some fuzziness of its pattern and depigmentation, indicate past uveitis and suggest (together with an assessment of the anamnesis and biomicroscopic picture) a consistent (complicated) nature of lens opacity. The presence of a coloboma of the iris upward indicates a former surgical intervention.

In some cases, with partial clouding of the lens, ophthalmoscopy is possible, which sometimes makes it possible to detect severe congenital pathology in the fundus (coloboma of the retina, choroid, etc.).

4. Sequential (complicated) cataracts (cataractae complicatae)

Sequential cataracts in children of different ages can occur with eye damage, uveitis, congenital glaucoma, diabetes, infectious nonspecific polyarthritis (Still's disease), etc.

Cataracts against the background of tuberculous uveitis are observed in about 1/5 of sick children, in most cases after iridocyclitis. Usually one eye is affected.

Opacification of the lens begins with its posterior sections in the form of a grayish veil or dots, as a result of which visual acuity is somewhat reduced. The turbidity may stabilize or regress. In some cases, the process progresses up to a complete clouding of the lens and a decrease in vision to light perception.

Eye damage due to infectious nonspecific polyarthritis, along with corneal dystrophy and uveitis, can be accompanied in most cases by cataracts. The process is usually two-way. Initially, opacities appear at the anterior surface of the lens, in the pupillary zone, in the form of pinpoint whitish-gray inclusions. Gradually they capture the cortical part of the lens to the embryonic nucleus, in rare cases reaching the central and then the posterior parts of the lens. The peripheral parts of the lens often remain transparent. Some children experience gross changes in the anterior capsule of the lens, caused by the organization of a whitish exudate with newly formed vessels and pigment inclusions. In this case, vision is reduced to light perception with correct projection.

Opacities of the lens in infectious nonspecific polyarthritis and tuberculous uveitis are observed in children older than one year. The most severe types of cataracts develop in predominantly older children with an acute course of the process in the eye.

Cataract in congenital glaucoma occurs in its advanced stage, with a pronounced stretching of the corneoscleral capsule of the eye.

Progressive cup-shaped gray opacities appear under the posterior lens capsule. The entire posterior capsule, posterior cortical and middle layers gradually become cloudy. The anterior lens capsule and anterior layers remain translucent for a long time.

Cataracts in children with hydrophthalmos can be unilateral or bilateral, but they usually do not occur simultaneously.

Diabetic cataract in children occurs in two clinical varieties: one is characterized by classical manifestations (the presence of subcapsular vacuoles and opacities, consisting of whitish dots, spots, flakes, extending to the cortical regions and beyond), the other combines atypical signs of cataract development, in which there is often no subcapsular opacities and vacuoles. The pathology of the lens is detected at any duration of the disease. Of primary importance is the severity of the process.

5. Senile cataract (cataracta senilis)

Senile cataracts are characterized by a slow progressive loss of vision. With initial cataracts (cataracta incipiens), visual acuity is usually high. With side illumination, no changes from the side of the lens can be detected. In transmitted light with a dilated pupil against the background of a pink reflex, one can see opacities on the periphery along the equator of the lens in the form of spokes or strokes or in the center if the cataract is nuclear.

If a patient has an immature (swelling) cataract (cataracta nondum matura s. intumescens), he complains of a significant decrease in vision. When illuminated from the side, a gray cloudy lens is visible in the pupil area. The lens may swell, causing the anterior chamber to become shallow. due to the existing transparent areas in the lens, the shadow of the iris is visible on it in lateral lighting, as well as a reflex from the fundus in transmitted light. Swelling of the lens can cause increased intraocular pressure.

Patients with mature cataracts (cataracta matura) are practically blind. Visual acuity is equal to light perception or hand movement near the face; there is no shadow from the iris, there is no reflex from the fundus.

If the cataract is overripe (cataracta hypermatura), then cholesterol deposits are observed in it in the form of white plaques on the anterior capsule of the lens, the nucleus may descend downwards, as the cortical substance liquefies. White plaques and a drooping nucleus are visible on combined examination and under the slit lamp.

Treatment of congenital and senile cataracts. Congenital cataracts that hardly affect visual acuity (for example, polar cataract, suture cataract) cannot be treated. Zonular, diffuse, membranous, nuclear and other cataracts are removed when visual acuity decreases to 0,2, and also if vision does not increase with pupil dilation.

As a rule, the operation is performed on children under two years of age. At a later age, surgical intervention is less advisable, since amblyopia develops, which requires long-term postoperative treatment.

With diffuse (complete) opacities of the lens, cataract extraction is performed. In the case of zonular and other partial cataracts, the operation is performed in two stages: first, the anterior lens capsule is dissected, and then, after 1012-XNUMX days, a simple (without iridectomy) extracapsular cataract extraction is performed. Intracapsular congenital cataracts are almost never removed, since the zonium ligaments in children are strong, elastic, and, in addition, their lens is firmly connected with the vitreous body.

With membranous cataracts, the operation of dissection of the excision of the lens capsule is indicated.

Senile cataracts are treated depending on the stage of the process and the state of the visual function. In the initial stage, the appointment of vitamin drops (cysteine, withiodurol, etc.) is shown, with a mature cataract, intracapsular extraction.

If visual acuity is very low, the patient is practically blind, and the cataract is not quite mature, intracapsular extraction is also performed. In elderly people, unlike children, due to the presence of a dense nucleus in the lens, it is often necessary to perform an iridectomy during surgery, i.e., the so-called combined cataract extraction is performed. If an iridectomy is not performed, the operation is called simple cataract extraction.

Treatment of consecutive cataracts is carried out depending on the etiology of the process and the degree of vision loss. For example, in diabetes, lens opacities may disappear under the influence of insulin therapy.

Before prescribing a patient for surgery, it is necessary to have the following additional data: the conclusion of the therapist to exclude somatic contraindications to surgical intervention, the results of chest x-ray, positive conclusions of the otolaryngologist and dentist, sowing from the conjunctiva, reaction to toxoplasmosis, Wasserman reaction, blood tests (general, coagulability and bleeding time), urinalysis.

On the eve of the operation, it is necessary to cut the eyelashes and shave the eyebrows. On the morning of the operation, a cleansing enema is done, the patient does not eat. Children are operated under anesthesia, adults under local anesthesia. The operating field is treated with alcohol, smeared with iodine, covered with sterile napkins.

In the postoperative period, the patient is on strict bed rest in the supine position for three days. For the prevention of postoperative iridocyclitis, mydriatics and anti-inflammatory drugs are prescribed. If the depth of the anterior chamber is not restored on the second or third day, this indicates poor adaptation of the edges of the postoperative wound or detachment of the choroid. In such cases, repeated intervention is required.

Author: Shilnikov L.V.

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