How does eye vision affect vision? Anterior-posterior axis of the eye (APO): the norm and increase in children and adults. Indications for this method
Thanks to the research, scientists have found that the trigger for development is an increase in intraocular pressure to a level exceeding the target. Intraocular pressure is an important physiological constant of the eye. It is regulated by several mechanisms. This indicator is influenced by some anatomical and physiological factors. The main ones are the volume of the eyeball and the size of the anterior-posterior axis of the eye. Studies conducted in recent years have led to the conclusion that glaucoma can develop as a result of a change in the biomechanical stability of the connective tissue structures of the fibrous capsule of the eye, and not just the area of the optic nerve head.
In ophthalmological studies, the following diagnostic methods are used:
- tonometry;
- tonography according to Nesterov and elastotonometry;
In young children, the upper limit of the norm of intraocular pressure may be a manifestation of a violation of the outflow of intraocular fluid. The length of the anteroposterior axis of the eyeball increases not only due to the accumulation of intraocular fluid and disturbance of the hemohydrodynamic processes of the organ of vision, but also due to the dynamics of pathological growth of the eye with age and degree. For the diagnosis of congenital glaucoma, it is necessary to use data from such examinations as echobiometry, gonioscopy, measurement of intraocular pressure. This should take into account the rigidity of the fibrous membrane of the eye and incipient glaucomatous optic neuropathy.
The anterior-posterior axis of the eyes is a fictitious line that runs parallel between the medial and lateral reticules at an angle of 45 degrees.
The axis connects the poles of the eyes.
With its help, you can set the distance from the tear film to the pigment part of the retina. In simple terms, the axis helps determine the length and size of the eyes. These indicators are very important in the diagnosis of many diseases.
The front-rear axle has the following dimensions:
- norm - up to 24.5 mm;
- newborn children - 18 mm;
- with farsightedness - 22 mm;
- with myopia - 33 mm.
Given these figures, it can be noted that newborns have the lowest rates. All babies have farsightedness, but eye growth stops until the age of three. At about 10 years old, a child develops normal vision. The axle size is approaching the 20 mm mark.
Genetics play an important role in the development of eye length. In an adult, the indicators of the anterior-posterior axis are not more than 24 mm. But there are exceptions when this mark rises to 27 mm. It depends on the height of the person. The final growth stops with the active development of the human body.
If the eyes constantly get used to stress in low light, then myopia begins to develop. Then the PZO indicators will be pathological. The risk of developing myopia is the same in children and adults, especially if they write in low light. If eye protection is not observed, the risk of developing myopia increases significantly.
It is imperative to monitor the PZO indicators if there are suspicions of refractive disorders in children and adolescents. This method is currently the only one for diagnosing and monitoring the progression of myopia. With the age of the child, the length of the eye reaches normal levels.
For each person, the length indicators may differ from the norm. In this case, the development of pathological changes or diseases is not observed. The body of each person is individual. Interestingly, the length of the eyeball may have a genetic inheritance. The measurement of the final size can be carried out when the growth of a person stops.
If the size of the PZO is not related to genetics, then the development of myopia is associated with labor activity or the educational process. In this case, the eyes begin to get used to uncomfortable conditions.
Children often face this phenomenon when they start going to school. In adults, myopia develops due to work activities, especially if you often have to work at a computer in low light. Therefore, it is important to give your eyes a rest during such work. Getting enough sleep will be especially helpful. Only then can the eyes be completely relaxed.
Doctors distinguish such a thing as accommodation. This implies an automatic process that allows, by changing the shape of the lens, to clearly and clearly see objects at different distances. It should be noted that accommodation has an acquired and congenital form. If the eyes are constantly straining when working close, then they begin to get used to such conditions. It is important to constantly monitor the indicators of PZO.
Everyone should visit an ophthalmologist periodically. This will help to avoid the development of serious diseases and pathological processes. In children under the age of 10 years, PZO indicators may vary and differ from the norm. This is considered normal as the eyeball is still developing. Each person may have different scores.
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research method used in ophthalmology to detect a wide range of eye pathologies. It is safe, informative, and sometimes completely irreplaceable.
This is especially true in cases where the diagnosis of intraocular diseases or structural anomalies is carried out with completely or partially cloudy eye media.
The ultrasound method allows you to study movements in the eyeball, evaluate the structure of the oculomotor muscles and the optic nerve, and obtain accurate data on the parameters of both normal and pathological (tumors, strictures, effusion) components of the eye.
Doppler study, which is almost always carried out in parallel with the main study of the structures of the eye, allows you to evaluate the blood flow velocity, volume, patency of the eye vessels. It also determines the pathology of the blood circulation of the eye even at the initial stages.
Who Should Get an Ultrasound of the Eye?
Indications for ultrasound of the eyeball are as follows:
- measurement of the parameters of the optical media of the eyeball
- assessment of the size of the orbit - the bone container of the eyeball
- diagnostics and control of treatment of intraocular and intraorbital tumors
- clouding of the optical media of the eye
- eye injury
- foreign body inside the eye: its definition, location, position relative to the structures of the eye, mobility, ability to be magnetized.
- myopia and farsightedness
- glaucoma
- cataract
- dislocation of the lens
- retinal detachment: Fundus ultrasound will help to identify not only the type of detachment, but also the stage of development of the disease, even if the environment of the eye has become cloudy due to any reason
- optic nerve disease
- destruction of the vitreous
- the method makes it possible to distinguish vitreous effusion from hemorrhages, its opacities
- adhesions in the vitreous
- Measurement of the thickness and properties of fatty tissue located behind the eyeball, which is indispensable for differentiating various forms of exophthalmos - "bulging eyes"
- oculomotor muscle pathology
- diagnostics and control over the effectiveness of treatment of vascular diseases of the eye
- congenital anomalies of the structure and blood supply of the eye.
- condition after surgery on the eyeball: it is especially important to assess the position of the lens that replaced the lens, its dislocation, the possibility of fusion with nearby structures
- diabetes
- hypertonic disease
- kidney disease, in which blood pressure rises and it is required to evaluate the condition of the fundus.
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Doppler ultrasound of the fundus allows you to identify and monitor the dynamics of:
- spasm or obstruction of the central retinal artery
- ischemic anterior neuroopticopathy
- thrombosis: superior ophthalmic vein, central retinal vein, cavernous sinus
- narrowing of the internal carotid artery, which can affect the direction and speed of blood flow in the arteries that feed the eye.
Study preparation
Before an ultrasound of the eye, you do not need to follow a specific diet or conduct any other preparation.
The study itself does not leave an imprint on the habitual way of life of a person.
The only feature: ladies should not apply makeup on their eyelids and eyelashes before the examination, as the procedure will require the application of a gel on the upper eyelid.
Contraindications for ophthalmoechography
The founder of the method Fridman F.E. believed that there were no contraindications to the study. It is possible to conduct an ultrasound examination of the eye for both pregnant and lactating women; oncological and hematological diseases are not a contraindication to the procedure.
Types of ultrasound scans of the eye
A-mode (or one-dimensional)
In this case, the doctor sees a graph in which:
- the horizontal axis means the distance to some structure that ultrasound travels per unit of time and returns back to the sensor
- the vertical axis is the amplitude and strength of the echo signal.
This method is indispensable for characterizing the tissues of the eye, it can be used to make various measurements of the eye (which is especially important before surgery), although it is rarely used as an independent method. 
B-mode
Recreates a two-dimensional picture of the eyeball, and the amplitude of the echo signal is displayed as dots of different brightness. This scan is necessary to get an idea of the internal structure of the eye.
Combined A + B-method
Combines the advantages of one- and two-dimensional scanning.
3D echo-ophthalmography
With the help of computer programs, a three-dimensional three-dimensional image of the eye and its vascular system is obtained; the program analyzes not just static dimensions, but also the change in curvature depending on the movement of the scanning plane.
Color duplex scanning
Evaluation of a two-dimensional image of the eye, together with the measurement of the speed and nature of blood flow in all nearby large, medium and small vessels.
How is an A-mode ultrasound of the eye done? The patient sits in a chair to the left of the doctor, an anesthetic is instilled into the examined eye to ensure the immobility of the eye and the painlessness of the study. A sterile sensor is driven directly over the eye, not covered by the eyelid.
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B-scan and various Doppler ultrasounds are performed through the closed eyelid with a special sensor, then it is not required to bury the eye. A special gel will be applied to the eyelid, which can be easily wiped off with a napkin after the examination. The procedure takes 10-15 minutes.
Evaluation of the results of the study
Decoding is carried out by the attending physician on the basis of the measurement data, as well as the conclusion made by the sonologist. So, normally:
- the lens should not be visible, as it is transparent, but its posterior capsule should be visualized
- the vitreous should also be transparent
- the length of the axis of the eye with normal vision is 22.4-27.3 mm
- refractive power of the eye with emmetropia: 52.6-64.21 D
- the optic nerve should be represented by a hypoechoic structure 2-2.5 mm wide
- the thickness of the inner shells ranges from 0.7-1 mm
- the anterior-posterior axis of the vitreous is about 16.5 mm, and its volume is about 4 ml.
Where to do the best ultrasound examination of the eyes is entirely your choice.
Now in every larger city there are several diagnostic centers - both multidisciplinary and ophthalmological - in which this procedure is performed.
The study should be carried out after a preliminary consultation with an ophthalmologist.
The average price of an ultrasound of the eye orbits is about 1300 rubles. The price range is from 900 to 5000 rubles.
Indications for eye ultrasound
- clouding of optical media;
- intraocular and intraorbital tumors;
- intraocular foreign body (its detection and localization);
- orbital pathology;
- measuring the parameters of the eyeball and orbit;
- eye injury;
- intraocular hemorrhages;
- retinal disinsertion;
- pathology of the optic nerve;
- vascular pathology;
- condition after eye operations;
- myopic disease;
- assessment of ongoing treatment;
- congenital anomalies of the eyeballs and orbits.
Contraindications for eye ultrasound
- injuries of the eyelids and periorbital region;
- open eye injuries;
- retrobulbar bleeding.
Normal values on ultrasound of the eyes
- the picture shows the posterior capsule of the lens, it is not visible;
- the vitreous body is transparent;
- eye axis 22.4 - 27.3 mm;
- refractive power with emmetropia: 52.6 - 64.21 D;
- the optic nerve is represented by a hypoechoic structure 2 - 2.5 mm;
- the thickness of the inner shells is 0.7-1 mm;
- anterior-posterior axis of the vitreous body 16.5 mm;
- vitreous body volume 4 ml.
Principles of ultrasound examination of the eye
Ultrasound of the eye is based on the principle of echolocation. When performing an ultrasound, the doctor sees an inverted image on the screen in black and white. Depending on the ability to reflect sound (echogenicity), tissues turn white. The denser the tissue, the higher its echogenicity and the whiter it appears on the screen.
- hyperechoic (white color): bones, sclera, vitreous fibrosis; air, silicone seals and IOL give a "comet tail";
- isoechoic (color light gray): fiber (or slightly elevated), blood;
- hypoechoic (color dark gray): muscles, optic nerve;
- anechoic (black color): lens, vitreous body, subretinal fluid.
Echostructure of tissues (the nature of the distribution of echogenicity)
- homogeneous;
- heterogeneous.
Contours of tissues during ultrasound
- normally equal;
- uneven: chronic inflammation, malignancy.
Ultrasound of the vitreous body
Hemorrhages in the vitreous body
Occupies a limited amount.
Fresh - blood clot (formation of moderately increased echogenicity, heterogeneous structure).
Absorbable - a fine suspension, often delimited from the rest of the vitreous body by a thin film.
Hemophthalmos
Occupy most of the vitreous cavity. A large mobile conglomerate of increased echogenicity, which can later be replaced by fibrous tissue, partial resorption is replaced by the formation of moorings.
Mooring lines
Coarse, fixed to the inner shells of the cord.
Retrovitreal hemorrhage
Finely punctate suspension in the posterior pole of the eye, limited by the vitreous body. May have a V-shape, simulating retinal detachment (with hemorrhage, the outer borders of the "funnel" are less clear, the top is not always associated with the optic disc).
Posterior vitreous detachment
It looks like a floating film in front of the retina.
Complete vitreous detachment
Hyperechoic ring of the boundary layer of the vitreous body with destruction of the inner layers, anechoic zone between the ring and the retina.
Retinopathy of prematurity
On both sides behind the transparent lenses fixed layered coarse opacities. At grade 4, the eyes are reduced in size, the membranes are thickened, compacted, and there is coarse fibrosis in the vitreous body.
Hyperplasia of the primary vitreous
Unilateral buphthalmos, shallow anterior chamber, often cloudy lens, behind fixed layered coarse opacities.
retinal ultrasound
Retinal disinsertion
Flat (height 1 - 2 mm) - to differentiate with the preretinal membrane.
Tall and domed - to differentiate with retinoschisis.
Fresh - the detached area in all projections connects with the adjacent area of the retina, is equal to it in thickness, sways during the kinetic test, pronounced folding, pre- and subretinal tractions are often found at the top of the detachment dome, it is rarely possible to see the place of the rupture. Over time, it becomes more rigid and, if more common, bumpy.
V-shaped - membranous hyperechoic structure, fixed to the membranes of the eye in the area of the optic disc and the dentate line. Inside the "funnel" is vitreous fibrosis (hyperechoic layered structures), outside - anechoic subretinal fluid, but in the presence of exudate and blood, echogenicity increases due to finely punctate suspension. Differentiate with organized retrovitreal hemorrhage.
As the funnel closes, it acquires a Y-shape, and with the fusion of a totally detached retina, a T-shape
epiretinal membrane
It can be fixed to the retina by one of the edges, but there is an area extending into the vitreous body.
Retinoschisis
The exfoliated area is thinner than the adjacent one, rigid during the kinetic test. A combination of retinal detachment with retinoschisis is possible - in the detached area there is a rounded, regular "encapsulated" formation.
Ultrasound of the choroid
Posterior uveitis
Thickening of the inner shells (thickness more than 1 mm).
Detachment of the ciliary body
A small film behind the iris exfoliated with anechoic fluid.
Choroid detachment
From one to several domed membranous structures of various heights and lengths, there are bridges between the exfoliated areas, where the choroid is fixed to the sclera; during the kinetic test, the blisters are immobile. The hemorrhagic nature of the subchoroidal fluid is visualized as a fine suspension. When it is organized, the impression of a solid education is created.
coloboma
Severe protrusion of the sclera occurs more often in the lower parts of the eyeball, often involving the lower parts of the optic disc, has a sharp transition from the normal part of the sclera, the vascular is absent, the retina is underdeveloped, covers the fossa or is detached.
staphyloma
A protrusion in the region of the optic nerve, the fossa is less pronounced, with a smooth transition to the normal part of the sclera, occurs when the PZO of the eye is 26 mm.
Ultrasound of the optic nerve
congested optic disc
Hypoechoic prominence? > 1 mm? with a surface. in the form of an isoechogenic strip, it is possible to expand the perineural space in the retrobulbar region (3 mm or more). Bilateral stagnant disc occurs with intracranial processes, unilateral - with orbital
Bulbar neuritis
Isoechoic prominence? > 1 mm? with the same surface, thickening of the inner membranes around the ONH
Retrobulbar neuritis
Expansion of the perineural space in the retrobulbar region (3 mm or more) with uneven, slightly blurred borders.
Disc ischemia
A picture of a congestive disc or neuritis, accompanied by a violation of hemodynamics.
Druze
Prominent hyperechoic round formation
coloboma
Associated with choroidal coloboma, deep optic disc defect of varying width, deforming the posterior pole and continuing into the optic nerve image
Ultrasound for foreign bodies in the eye
Ultrasound signs of foreign bodies: high echogenicity, "comet tail", reverberation, acoustic shadow.
Ultrasound for volumetric intraocular formations
Patient examination
The diagnostic algorithm should be followed: 
- conduct CDS;
- if a vascular network is detected, conduct pulsed wave Doppler sonography;
- in the triplex ultrasound mode, assess the degree and nature of vascularization, quantitative indicators of hemodynamics (required for dynamic monitoring);
- echodensitometry: carried out using the "Histogram" function under standard scanner settings, except for G (Gain) (40 - 80 dB can be selected).
T is the total number of pixels of any shade of gray in the region of interest.
L is the level of the shade of gray that prevails in the area of interest.
M - the number of grayscale pixels prevailing in the area of interest
Calculation
Homogeneity index: IH = M / T x 100 (melanoma recognition confidence 85%)
Echogenicity index: IE = L / G (melanoma recognition reliability 88%); - triplex ultrasound in dynamics.
Melanoma
A wide base, a narrower part - a stem, a wide and rounded hat, a heterogeneous hypo-, isoechoic structure, with CDS, the development of its own vascular network is detected (almost always a feeding vessel growing along the periphery is determined, vascularization varies from a dense network to single vessels, or " avascular" due to the small diameter of the vessels, stasis, low blood flow velocity, necrosis); rarely can have an isoechoic homogeneous structure.
Hemangioma
Slight hyperechoic heterogeneous prominence, disorganization and proliferation of the pigment epithelium over the focus with the formation of multilayer structures and fibrous tissue, calcium salt deposition is possible; arterial and venous type of blood flow in CDS, slow growth, may be accompanied by secondary retinal detachment.
Sources
Expand- Zubarev A.V. - Diagnostic ultrasound. Ophthalmology (2002)
Myopia is an actual clinical and social problem. Among schoolchildren of general education schools, 10-20% suffer from myopia. The same frequency of myopia is observed in the adult population, since it occurs mainly in
I. L. Ferfilfain, Doctor of Medical Sciences, Professor, Chief Researcher, Yu. L. Poveshchenko, Candidate of Medical Sciences, Senior Researcher; Research Institute of Medical and Social Problems of Disability, Dnepropetrovsk
Myopia is an actual clinical and social problem. Among schoolchildren of general education schools, 10-20% suffer from myopia. The same frequency of myopia is observed among the adult population, since it occurs mainly at a young age and does not go away with age. In Ukraine, in recent years, about 2 thousand people are annually recognized as disabled due to myopia and about 6 thousand are registered with medical and social expert commissions.
Pathogenesis and clinic
The fact of a significant prevalence of myopia among the population determines the relevance of the problem. However, the main thing is in different opinions regarding the essence and content of the concept "myopia". Treatment, prevention, professional orientation and suitability, the possibility of hereditary transmission of the disease, and prognosis depend on the interpretation of the pathogenesis and clinic of myopia.
The bottom line is that myopia as a biological category is an ambiguous phenomenon: in most cases it is not a disease, but a biological version of the norm.
All cases of myopia are united by a manifest sign - the optical setting of the eye. This is a physical category characterized by the fact that with a combination of certain optical parameters of the cornea, lens and the length of the anteroposterior axis of the eye (APO), the main focus of the optical system is located in front of the retina. This optical feature is characteristic of all types of myopia. Such an optical setting of the eye can be due to various reasons: elongation of the anteroposterior axis of the eyeball or high optical power of the cornea and lens with a normal length of the ASO.
The initial pathogenetic mechanisms of the formation of myopia are not well understood, including hereditary pathology, intrauterine diseases, biochemical and structural changes in the tissues of the eyeball during the growth of the organism, etc. The immediate causes of the formation of myopic refraction (pathogenesis) are well known.
The main characteristics of myopia are considered to be a relatively large length of the posterior eye of the eyeball and an increase in the optical power of the refractive system of the eyeball.
In all cases of PZO increase, the optical setting of the eye becomes myopic. The type of myopia determines the following reasons for the increase in the length of the eyeball PZO:
- the growth of the eyeball is genetically determined (normal variant) - normal, physiological myopia;
- excessive growth due to the adaptation of the eye to visual work - adaptive (working) myopia;
- myopia due to a congenital malformation of the shape and size of the eyeball;
- diseases of the sclera, leading to its stretching and thinning - degenerative myopia.
An increase in the optical power of the refractive system of the eyeball is one of the main characteristics of myopia. Such an optical setting of the eye is observed when:
- congenital keratoconus or phacoconus (anterior or posterior);
- acquired progressive keratoconus, that is, stretching of the cornea due to its pathology;
- phacoglobus - acquired spherical shape of the lens due to weakening or rupture of the ciliary ligaments that support its elliptical shape (with Marfan's disease or due to injury);
- a temporary change in the shape of the lens due to a dysfunction of the ciliary muscle - a spasm of accommodation.
Various mechanisms of the formation of myopia have led to the pathogenetic classification of myopia, according to which myopia is divided into three groups.
- Normal, or physiological, myopia (healthy eyes with myopic refraction) is a variant of a healthy eye.
- Conditionally pathological myopia: adaptive (working) and false myopia.
- Pathological myopia: degenerative, due to congenital malformation of the shape and size of the eyeball, congenital and juvenile glaucoma, malformation and disease of the cornea and lens.
Healthy myopic eyes and adaptive myopia are recorded in 90-98% of cases. This fact is very important for adolescent ophthalmic practice.
Spasm of accommodation is rare. The opinion that this is a frequent condition that precedes the onset of true myopia is recognized by few ophthalmologists. Our experience shows that the diagnosis of "accommodation spasm" with initial myopia in most cases is the result of a research defect.
Pathological types of myopia - severe eye diseases that become a common cause of low vision and disability, occur only in 2-4% of cases.
Differential Diagnosis
Physiological myopia in most cases occurs in first grade students and gradually progresses until growth is completed (in girls - up to 18 years old, in boys - up to 22 years old), but it may stop earlier. Often such myopia is observed in parents (one or both). Normal myopia can reach 7 diopters, but more often it is weak (0.5-3 diopters) or moderate (3.25-6 diopters). At the same time, visual acuity (with glasses) and other visual functions are normal, pathological changes in the lens, cornea, and eyeball membranes are not observed. Often, with physiological myopia, there is a weakness of accommodation, which becomes an additional factor in the progression of myopia.
Physiological myopia can be combined with working (adaptive) myopia. The insufficiency of the function of the accommodation apparatus is partly due to the fact that short-sighted people do not use glasses when working close, and then the accommodation apparatus is inactive, and, as in any physiological system, its functionality is reduced.
Adaptive (working) myopia, as a rule, is weak and rarely moderate. Changing the conditions of visual work and restoring the normal volume of accommodation stops its progression.
Spasm of accommodation - false myopia - occurs under adverse conditions of visual work near. It is diagnosed quite easily: first, the degree of myopia and the volume of accommodation are determined, by instillation of atropine-like substances into the eyes, cycloplegia is achieved - relaxation of the ciliary muscle that regulates the shape and, consequently, the optical power of the lens. Then the volume of accommodation is re-determined (0-0.5 diopters - complete cycloplegia) and the degree of myopia. The difference between the degree of myopia at the beginning and against the background of cycloplegia will be the magnitude of the spasm of accommodation. This diagnostic procedure is carried out by an ophthalmologist, given the possibility of increased sensitivity of the patient to atropine.
Degenerative myopia is registered in the International Statistical Classification of Diseases ICD-10. Previously, it was defined as dystrophic due to the predominance of dystrophic changes in eye tissues in its clinical manifestations. Some authors call it myopic disease, malignant myopia. Degenerative myopia is relatively rare, occurring in about 2-3% of cases. According to Frank B. Thompson, in Europe the frequency of pathological myopia is 1-4.1%. According to N. M. Sergienko, in Ukraine dystrophic (acquired) myopia occurs in 2% of cases.
Degenerative myopia, a severe form of eye disease that can be congenital, often begins in preschool age. Its main feature is the gradual, throughout life, stretching of the sclera of the equatorial and especially the back of the eyeball. The magnification of the eye along the anteroposterior axis can reach 30-40 mm, and the degree of myopia - 38-40 diopters. The pathology progresses and after the completion of the growth of the organism, with the stretching of the sclera, the retina and choroid are stretched.
Our clinical and histological studies have revealed significant anatomical changes in the vessels of the eyeball in degenerative myopia at the level of ciliary arteries, vessels of the Zinn-Haller circle, which lead to the development of degenerative changes in the eye membranes (including the sclera), hemorrhages, retinal detachment, the formation of atrophic foci, etc. It is these manifestations of degenerative myopia that lead to a decrease in visual functions, mainly visual acuity, and to disability.
Pathological changes in the fundus of the eye in degenerative myopia depend on the degree of stretching of the membranes of the eye.
Myopia due to a congenital malformation of the shape and size of the eyeball is characterized by an increase in the eyeball and, therefore, high myopia at the time of birth. After birth, the course of myopia stabilizes, only a slight progression is possible during the period of growth of the child. Characteristic for such myopia is the absence of signs of stretching of the membranes of the eye and dystrophic changes in the fundus, despite the large size of the eyeball.
Myopia due to congenital or juvenile glaucoma is caused by high intraocular pressure, which causes stretching of the sclera and, consequently, myopia. It is observed in young people who have not yet completed the formation of the sclera of the eyeball. In adults, glaucoma does not cause nearsightedness.
Myopia due to congenital malformations and diseases of the cornea and lens is easily diagnosed using a slit lamp (biomicroscopy). It should be remembered that a severe disease of the cornea - progressive keratoconus - may initially manifest itself as mild myopia. The above cases of myopia due to a congenital malformation of the shape and size of the eyeball, cornea and lens are not the only ones of their kind. The monograph by Brian J. Curtin lists 40 types of congenital eye defects accompanied by myopia (as a rule, these are syndromic diseases).
Prevention
Normal myopia, as genetically determined, cannot be prevented. At the same time, the exclusion of factors contributing to its formation prevents the rapid progression of the degree of myopia. We are talking about intense visual work, poor accommodation, other diseases of the child (scoliosis, chronic systemic diseases), which can affect the course of myopia. Moreover, normal myopia is often combined with adaptive myopia.
Working (adaptive) myopia can be prevented if the factors listed above that contribute to its formation are excluded. At the same time, it is advisable to investigate accommodation in children before school. Schoolchildren with weakened accommodation are at risk of myopia. In these cases, it is necessary to restore accommodation in full, create optimal conditions for visual work under the supervision of an oculist.
If myopia is hereditary, then it can be prevented using reproductive medicine methods. This opportunity is very relevant and promising. Approximately half of the blind and visually impaired children are severely disabled due to hereditary eye diseases. The living and working conditions of blind and visually impaired people form a vicious circle of communication. The probability of having children with a hereditary pathology increases dramatically. This vicious circle cannot be broken only by educational work among parents - carriers of hereditary pathology, in order to save their children from a difficult fate. Prevention of hereditary blindness and low vision can be solved by implementing a special national program that would provide for genetic counseling and methods of reproductive medicine for the blind and visually impaired - carriers of hereditary pathology.
Treatment
In treatment, as in prevention, the type of myopia is of particular importance.
With normal (physiological) myopia, it is impossible to eliminate the genetically provided parameters of the eyeball and the characteristics of the optical apparatus with the help of treatment. You can only correct the influence of adverse factors that contribute to the progression of myopia.
In the treatment of physiological and adaptive myopia, it is advisable to use methods that develop accommodation and prevent its overstrain. To develop accommodation, many methods are used, each of which has no particular advantage. Every optometrist has their favorite treatments.
With myopia due to malformations, the treatment options are very limited: the shape and size of the eye cannot be changed. The methods of choice are changing the optical power of the cornea (surgically) and extraction of the transparent lens.
In the treatment of degenerative myopia, there are no methods that can radically affect the process of stretching the eyeball. In this case, refractive surgery and treatment of dystrophic processes (medication and laser) are performed. With initial dystrophic changes in the retina, angioprotectors are used (Ditsinon, doxium, prodectin, ascorutin); with fresh hemorrhages in the vitreous body or retina - antiplatelet agents (trental, Ticlid) and hemostatic drugs. To reduce extravasation in the wet form of central chorioretinal dystrophy, diuretics and corticosteroids are used. In the phase of reverse development of dystrophies, it is recommended to prescribe absorbable agents (collisin, fibrinolysin, lecozyme), as well as physiotherapy: magnetotherapy, electrophoresis, microwave therapy. In order to prevent peripheral retinal breaks, laser and photocoagulation are indicated.
Separately, we should dwell on the treatment of myopia using scleroplasty methods. In the United States and Western European countries, it was abandoned long ago as ineffective. At the same time, in the CIS countries, scleroplasty has become the most widespread (it is used even in children with physiological or adaptive myopia, in whom it is not associated with stretching of the eyeball, but is the result of body growth). Often the cessation of the progression of myopia in children is interpreted as the success of scleroplasty.
Our studies have shown that scleroplasty is not only useless and illogical for normal and adaptive myopia (namely, these types of myopia in most schoolchildren), but is ineffective for degenerative myopia. In addition, this operation can cause various complications.
Optical correction of myopia
Before performing optical correction of myopia, two issues must be resolved. Firstly, do children with physiological and adaptive myopia need glasses and contact lenses and in what cases? Secondly, what should be the optical correction in patients with high and very high myopia. Often, doctors believe that with mild myopia there is no need to wear glasses, since this is a spasm of accommodation, and they make such a conclusion without an appropriate differential diagnosis. In many cases, glasses are assigned only for distance. These opinions of doctors are not scientifically substantiated. As already noted, the weakness of accommodation contributes to the progression of myopia, and the weakness of accommodation - work without glasses near. Thus, if a student with myopia does not use glasses, then his progression is aggravated.
Our research and practical experience show that schoolchildren with mild to moderate myopia need to be prescribed a full correction (glasses or contact lenses) for permanent wear. This ensures the normal function of the accommodation apparatus, which is characteristic of a healthy eye.
The question of optical correction of myopia over 10-12 diopters is difficult. With such myopia, patients often do not tolerate full correction and, therefore, they cannot fully restore visual acuity with the help of glasses. Studies have shown that, on the one hand, intolerance to spectacle correction is more often observed in people with a weak vestibular apparatus; on the other hand, the maximum correction itself can be the cause of vestibular disorders (Yu. L. Poveshchenko, 2001). Therefore, when prescribing, one should take into account the subjective sensations of the patient and gradually increase the optical power of the glasses. Such patients tolerate contact lenses more easily, they provide higher visual acuity.
Social adaptation of myopic people
This question arises when choosing a profession and study, while providing conditions that are harmless for the course of myopia, and finally, in connection with disability.
With normal (physiological) myopia, almost all types of professional activities are available, with the exception of those that require high visual acuity without optical correction. It should be borne in mind that unfavorable conditions of professional activity can be an additional factor in the progression of myopia. This primarily applies to children and adolescents. In modern conditions, the issue of the mode of operation with computers, which are regulated by special orders of the SES, is topical.
With working (adaptive myopia), a wide range of professions is available. However, one should remember what contributes to the formation of this type of myopia: weakness of accommodation, work close to small objects in low light and contrast. With normal and adaptive myopia, the problem is not in limiting work activity, but in observing certain conditions of visual hygiene.
The issues of social adaptation of persons with pathological myopia are solved in a fundamentally different way. In severe eye diseases, the treatment of which is ineffective, the choice of profession and working conditions is especially important. Among people with pathological myopia, only a third are recognized as disabled. The rest, thanks to the right choice of professional activity and with systematic supportive treatment, retain their social status almost all their lives, which, of course, is more worthy than the status of a disabled person. There are other cases when young people with degenerative myopia get a job where the state of vision is not taken into account (as a rule, this is heavy unskilled physical labor). Over time, due to the progression of the disease, they lose their jobs, and the possibility of new employment is extremely limited.
It should be noted that the social well-being of people with pathological myopia largely depends on optical correction, including surgical correction.
In conclusion, I would like to note the following. It is impossible to cover all aspects of such a complex problem as myopia in a short article. The main points that the authors tried to focus on are the following:
- in the treatment, prevention, examination of working capacity, differential diagnosis of the type of myopia is important;
- there is no need to dramatize the fact of myopia in schoolchildren, it is, with rare exceptions, not pathological;
- degenerative and other types of pathological myopia - severe eye diseases that lead to low vision and disability, require constant treatment and follow-up;
- scleroplasty is ineffective, it is not recommended for children.
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