Squint - a constant or periodic deviation of a visual axis of an eye from a fixing point that leads to violation of binocular sight. Squint is shown by an outer defect – a deviation of eyes/a eyes to a nose or a temple, up or down. Besides at the patient with squint dizzinesses and headaches, decrease in sight, an ambliopiya can be noted doubling in eyes. Diagnosis of squint includes ophthalmologic inspection (visual acuity check, biomicroscopy, perimetry, an oftalmoskopiya, a skiaskopiya, refractometry, biometric researches of an eye, etc.), neurologic inspection. Treatment of squint is carried out by means of-point or contact correction, beauty equipment procedures, pleoptichesky, ortoptichesky and diploptichesky techniques, surgical correction.
In children's ophthalmology squint (a geterotropiya or a strabizm) occurs at 1,5-3% of children, with an identical frequency at girls and boys. As a rule, squint develops at 2-3-year age when sodruzhestvenny work of both eyes is formed; however, also congenital squint can meet.
Squint is not only cosmetic defect: this disease leads to work violation practically of all departments of the visual analyzer and can be followed by a number of visual frustration. At squint the rejection of the provision of one or both eyes from the central axis leads to the fact that visual axes do not cross on the fixed subject. In this case in the visual centers of a cerebral cortex there is no merge of the monocular images which are separately perceived by the left and right eye in a uniform vision, and there is a double image of an object. For protection against doubling of TsNS suppresses signals, received from the mowing eye that leads eventually to an ambliopiya - functional decrease in sight at which honor the mowing eye or is not involved in visual process at all. In the absence of treatment of squint development of an ambliopiya and decrease in sight happens approximately at 50% of children.
Besides, squint adversely influences formation of mentality, promoting development of isolation, negativism, irritability, and also imposing restrictions for choice of profession and spheres activity of the person.
Classification of squint
On terms of emergence distinguish squint congenital (infantile - is available since the birth or develops in the first 6 months) and acquired (usually develops up to 3 years). On the basis of stability of a deviation of an eye allocate periodic (passing) and constant squint.
Taking into account an involvement of eyes squint can be unilateral (monolateral) and alternating (alternating) – in the latter case alternately mows one, other eye.
On degree of expressiveness distinguish squint hidden (geteroforiya), compensated (comes to light only at ophthalmologic inspection), subcompensated (arises only when weakening control) and dekompensirovanny (does not give in to control).
Depending on that direction where the mowing eye deviates, allocate the horizontal, vertical and mixed squint. Horizontal squint can be meeting (an ezotropiya, the converging squint) – in this case the mowing eye is rejected to a nose bridge; and dispersing (an ekzotropiya, the diverging squint) – the mowing eye is rejected to a temple. In vertical squint also allocate two forms with eye shift up (a gipertropiya, supravergiruyushchy squint) and from top to bottom (a gipotropiya, infravergiruyushchy squint). In certain cases the tsiklotropiya – a torsion geterotropiya at which the vertical meridian is inclined towards a temple (ekstsiklotropiya) or towards a nose (intsiklotropiya) meets.
From the point of view of the causes allocate sodruzhestvenny and paralytic nesodruzhestvenny squint. In 70-80% of cases sodruzhestvenny squint happens meeting, in 15-20% - dispersing. Torsion and vertical deviations, as a rule, meet at paralytic squint.
At sodruzhestvenny squint of the movement of eyeballs in various directions are kept in full, there is no diplopiya, there is a violation of binocular sight. Sodruzhestvenny squint can be akkomodatsionny, partial , neakkomodatsionny.
Akkomodatsionny sodruzhestvenny squint develops at the age of 2,5-3 years in connection with existence of high and average degrees of far-sightedness, short-sightedness, an astigmatism more often. In this case application of corrective points or contact lenses, and also hardware treatment will promote recovery of the symmetric provision of eyes.
Signs partial and neakkomodatsionny squint appear at children of 1st and 2nd of life. At these forms of sodruzhestvenny squint anomaly of a refraction is not the only reason of a geterotropiya therefore recovery of the provision of eyeballs requires performing surgical treatment.
Development of paralytic squint is connected with damage or paralysis of glazodvigatelny muscles owing to pathological processes in muscles, nerves or a brain. At paralytic squint mobility of the rejected eye towards the affected muscle is limited, there is a diplopiya and violation of binocular sight.
Developing of congenital (infantile) squint can be connected with the family anamnesis of a geterotropiya – presence of squint at close relatives; genetic disorders (Kruzon's syndrome, Down syndrome); teratogenny influence on a fruit of some medicines, narcotic substances, alcohol; premature birth and the child's birth with low body weight; cerebral palsy, hydrocephaly, congenital defects of eyes (congenital cataract).
Development of the acquired squint can happen sharply or gradually. As the reasons of secondary sodruzhestvenny squint at children serve ametropiya (an astigmatism, far-sightedness, short-sightedness); at the same time at a miopiya develops more often dispersing, and at a gipermetropiya - the meeting squint. Stresses, high visual loadings, children's infections (measles, scarlet fever, diphtheria, flu) and the general diseases (juvenile rheumatoid arthritis) proceeding with high fever can provoke development of squint.
At advanced age, including at adults, the acquired squint can develop against the background of a cataract, a leykoma (cataract), an atrophy of an optic nerve, the otsloyka of a retina, a degeneration of a makula leading to sharp decrease in sight of one or both eyes. Carry tumors (retinoblastoma), craniocereberal injuries, parayolich of craniocereberal neyorv to risk factors of paralytic squint (glazodvigatelny, block, taking away), neuroinfections (meningitis, encephalitis), strokes, changes of a wall and a bottom of an eye-socket, multiple sclerosis, a myasthenia.
As objective symptom of any kind of squint serves asymmetric position of an iris and a pupil in relation to an eye crack.
At paralytic squint mobility of the rejected eye towards the paralyzed muscle is limited or is absent. The diplopiya and dizzinesses which disappear when closing one eye, impossibility is noted it is correct to estimate location of a subject. At paralytic squint the corner of primary deviation (mowing eyes) is less, than a corner of a secondary deviation (a healthy eye), i.e. in attempt of fixing of a point the mowing eye, a healthy eye deviates on a much bigger corner.
The patient with paralytic squint forcedly turns or inclines the head aside to compensate sight violations. This adaptable mechanism promotes the passive translation of the image of an object on the central pole of a retina, saving thereby from doubling and providing not quite perfect binocular sight. The compelled inclination and turn of the head at paralytic squint should be distinguished from that at a wryneck, otitis.
In case of damage of a glazodvigatelny nerve expansion of a pupil, a deviation of an eye of a knaruzha and from top to bottom is noted centuries, there is a partial oftalmoplegiya and paralysis of accommodation.
Unlike paralytic squint, at a sodruzhestvenny geterotropiya, the diplopiya, as a rule, is absent. The volume of the movement of the mowing and fixing eyes approximately identical and unlimited, corners of primary and secondary deviation are equal, functions of glazodvigatelny muscles are not broken. When fixing a look on a subject one or alternately both eyes deviate in any party (to a temple, a nose, up, down).
Sodruzhestvenny squint can be horizontal (meeting or dispersing), vertical (supravergiruyushchy or infravergiruyushchy), torsion (tsiklotropiya), combined; monolateral or alternating.
Monolateral squint leads to the fact that visual function of the rejected eye constantly is suppressed with the central department of the visual analyzer that is followed by decrease in visual acuity of this eye and development of a disbinokulyarny ambliopiya of various degree. At alternating squint the ambliopiya, as a rule, does not develop or is expressed slightly.
Diagnosis of squint
When collecting the anamnesis specify terms of developing of squint and its communication with the postponed injuries and diseases. During external examination pay attention to the compelled position of the head (at paralytic squint), estimate symmetry of the person and eye cracks, position of eyeballs (, ).
Then check of visual acuity without correction and with trial lenses is made. For definition of optimum correction by means of a skiaskopiya and computer refractometry the clinical refraction is investigated. If against the background of a tsikloplegiya squint disappears or decreases, it indicates the akkomodatsionny nature of pathology. Forward departments of an eye, transparent environments and an eye bottom are investigated by means of biomicroscopy, an oftalmoskopiya.
For a research of binocular sight test with an eye prikryvaniye is carried out: the mowing eye at the same time deviates aside; by means of the device of a sinoptofor fusional ability (ability to merge of images) is estimated. Measurement of a corner of squint (size of a deviation of the mowing eye), a convergence research, accommodation scoping is performed.
Treatment of squint
At sodruzhestvenny squint as a main goal of treatment serves restoration of binocular sight at which asymmetry of position of eyes is eliminated and visual functions are normalized. Actions can include optical correction, pleoptiko-ortoptichesky treatment, surgical correction of squint, before - and postoperative ortoptodiploptichesky treatment.
During optical correction of squint the visual acuity restoration aim, and also normalization of a ratio of accommodation and convergence is pursued. The exaction of points or contact lenses is for this purpose made. At akkomodatsionny squint of it happens enough for elimination of a geterotropiya and restoration of binocular sight. Meanwhile,-point or contact correction of an ametropiya is necessary at any form of squint.
Pleoptichesky treatment is shown at an ambliopiya for strengthening of visual load of the mowing eye. For this purpose occlusion can be appointed (switching off from sight process) the fixing eye, to be used the penalization, to be appointed hardware stimulation of an ambliopichny eye (Ambliokor, Ambliopanorama, program and computer treatment, an accommodation training, an elektrookulostimulyation, a lazerstimulyation, magnetostimulation, photostimulation, vacuum ophthalmologic massage). The Ortoptichesky stage of treatment of squint is directed to restoration of the coordinated binocular activity of both eyes. Synoptic devices (Sinoptofor), computer programs are for this purpose used.
At the final stage of treatment of squint the diploptichesky treatment directed development of binocular sight under natural conditions is carried out (trainings with Bagolini's lenses, prisms); the gymnastics for improvement of mobility of eyes, trainings on a konvergentstrener is appointed.
Surgical treatment of squint can be undertaken if the effect of conservative therapy is absent within 1-1,5 years. It is optimum to carry out expeditious correction of squint at the age of 3-5 years. In ophthalmology surgical reduction or elimination of a corner of squint is often carried out step by step. Operations of two types are applied to correction of squint: weakening and strengthening function of glazodvigatelny muscles. Weakening of muscular regulation is reached by means of change (recession) of a muscle or crossing of a sinew; strengthenings of action of a muscle try to obtain by its resection (shortening).
Before operation on correction of squint ortoptichesky and diploptichesky treatment for elimination of residual deviation is shown. Success of surgical correction of squint makes 80-90%. The giperkorrekyotion and insufficient correction a kosoglayoziya can be complications of surgical intervention; in rare instances - infekyotion, bleeding, sight loss.
As criteria of treatment of squint serve symmetry of position of eyes, stability of binocular sight, high visual acuity.
Forecast and prevention of squint
Treatment of squint needs to be begun, as soon as possible, that by the beginning of school training the child was sufficiently rehabilitated concerning visual functions. Practically in all cases at squint persistent, consecutive and long-term complex treatment is required. Late begun and inadequate correction of squint can lead to irreversible decrease in sight.
Most successfully sodruzhestvenny akkomodatsionny squint gives in to correction; at late revealed paralytic squint the forecast of restoration of full visual function adverse.
Prevention of squint demands regular surveys of children by the ophthalmologist, timely optical correction of ametropiya, observance of requirements of hygiene of sight, dosage of visual loadings. Early identification and treatment of any diseases of eyes, infections, prevention of injuries of skull is necessary. In the course of pregnancy it is necessary to avoid adverse effects on a fruit.