Cross-eye or heterotropy (strabismus) is a pathology of vision. When strabismus eyes have an incorrect installation and deviate away from the normal angle of view, not focusing on one point.
We look with two eyes in the same direction, but several different images from the left and right eyes enter the brain. In the area of the visual cortex, the brain superimposes the images one by one and creates a real, single image that is three-dimensional and three-dimensional – this is normal binocular vision.
For strabismus the focus of each eye falls on different points, and the images are too different. In this case, the brain can not put them in a single picture, and it turns out the imbalance of vision.
In order not to get confused, the brain begins to turn off the image from the affected eye, gradually turning it off from the vision process. A sick eye has a progressive decrease in vision amblyopia .
With strabismus, amblyopia develops quite quickly, but with proper treatment, vision can be fully restored. With a not very high degree of strabismus, the pictures may overlap, but the image may be doubled.
Strabismus can be
- congenital because of hereditary predisposition, pathological course of pregnancy, malformations or congenital abnormalities of the eye muscles,
- acquired as a result of traumas, diseases, infections, pathologies of vision, etc.
Also causes strabismus can serve
- injuries or swelling of the eyes, eye muscle defects, abnormal vision,
- paralysis or paresis of the eye muscles,
- thyroid problems
- measles or influenza affection,
- strong fear, neurosis.
Friendly strabismus is distinguished when both eyes deviate from the normal axis, and mono-lateral – when one eye mainly suffers.
- Apparent squint, it occurs in children up to six months due to floating eye movements. In addition, the apparent strabismus occurs in children with a broad nose.
- Hidden strabismus, manifested due to the difference in muscle strength from different sides. If the child looks with two eyes, strabismus is not noticeable, but if the child looks with one eye, having closed the other, the second one can deviate.
- True. Permanent strabismus, which is detected under all conditions.
Strabismus can be
- converging (esotropia), when one or both eyes converge towards the nose,
- divergent (exotropic), when one or both eyes diverge towards the temple,
- vertical when the eye goes up (hypertropia) or down (hypotropia),
- mixed when several previous forms can be combined.
Depending on the characteristics of accommodation (vision problems) may occur
- non-accommodating squint, in which the correction does not depend on the glasses, and only surgery helps,
- partial accommodative squint, when corrected with glasses or lenses, it is partially compensated,
- accommodative squint, with the correct selection of glasses it is eliminated.
By the magnitude of the deviation from the normal axis of vision, squint can be
- insignificant, with a deviation of up to 5 °
- small, with a deviation from 6 to 10 °
- average, with a deviation from 11 to 20 °
- pronounced, with a deviation from 21 to 35 °
- very pronounced, with a deviation above 36 °.
The main sign of strabismus is a visually noticeable deviation of the eye from the normal position.
In addition, when strabismus can also be forced position of the head, the child constantly tilts or turns it to the side. This is necessary to compensate for the split picture.
The child may squint, he has a headache or dizziness, reduced vision with the affected eye.
In the case of paralytic strabismus, the affected eye is deflected to the side, partially or completely immobile, eyesight in the affected eye is severely impaired.
Children or adult ophthalmologists deal with the problems of strabismus.
In addition to visual inspection and establishment of the fact of strabismus, it is necessary to carry out some diagnostic methods:
- determination of visual acuity with and without lens correction,
- determining the amount of eye movement when tracking objects (up-down, left-right),
- perimetry (definition of visual fields),
- examination of the fundus of the eye with the dilated pupil, the definition of refraction (the refractive power of the medium of the eye in diopters),
- carrying out a four-point color test, with the help of which the patient sees with one or both eyes (monocular or binocular vision),
- In addition, ultrasound of the eye and computed tomography can be performed to exclude organic causes of strabismus (tumors, hematomas, defects).
Sometimes consultation of the neurologist and the endocrinologist is required.
Treatment of strabismus should be started as early as possible to prevent vision loss ( amblyopia ) with a squinting eye.
Squint correction without surgery
First of all, the elimination of the causes that provoked strabismus. In addition, it is necessary to achieve the complete elimination of strabismus or at least make it less pronounced.
If strabismus arises due to poor vision, eyeglass correction or lenses are selected in accordance with the degree of vision loss.
Spectacle correction is carried out not earlier than 6-10 months, as before this squint may be due to the peculiarities of vision.
After that, apply the methods of sticking – during the day close the eye, which sees better. At the same time, the squinting eye becomes the leading one, and its visual acuity improves.
Apply also special devices to improve vision and fixing the center position of the eye.
As they achieve the necessary visual acuity, they develop the ability of the eye to merge images and friendly movements without deviations. Eyes give different parts of the pictures that need to be connected, properly giving the installation of the eyes on special devices (binarimeters or synoptophores). Apply physiotherapy.
Surgical correction of strabismus
With a high degree of deviation of the eye, more than 10 degrees, apply a preliminary surgical correction, and then complement it with the methods described above.
The operation does not cancel the use of further methods of conservative therapy, but is only one of the stages of treatment.
Indications for surgery:
- the progression of the process, despite the therapeutic activities,
- no effect from wearing glasses or lenses for a year or more,
- large angle of strabismus.
If the angle is more than 30 degrees, they operate in two stages, as well as with bilateral strabismus, operations are prescribed with an interval of six months – first one eye, then the second.
The operation is to shorten or lengthen the muscles of the eye, depending on the form of strabismus.
The prognosis for timely treatment is favorable, but in the advanced stages there may be irreversible loss of vision in one eye with the impossibility of acquiring in the future certain occupations and imposing certain restrictions in life (driving vehicles, playing sports).