Examination of eye movements

The study of eye movements includes assessment of eye movement control and assessment of saccades.

1. Versions are assessed in 8 eccentric positions of the eye. Usually, the patient monitors the object (pen or pocket flashlight), which allows you to evaluate corneal reflexes. Movements in these directions can be caused arbitrarily, acoustically or with the help of the "head of the doll" maneuver.
2. Duktsy is assessed with the limitation of the mobility of the muscle on one or two eyes. A pocket flashlight is necessary for an accurate assessment of corneal reflexes. The paired eye is closed and the patient watches the light source in different positions of the eye. A simple system for estimating mobility from 0 (full motion) and from -1 to -4 indicates the degree of increase in the violation of the function.

[1], [2], [3], [4], [5], [6]

Nearest convergence point

This is the point at which fixation is supported binocularly. It can be evaluated using the RAF ruler, which is placed on the cheeks of the patient. The object is slowly moved in the direction of the eyes until one of them stops fixing it and deviates to the side (the objective nearest convergence point). The subjective nearest convergence point is the point at which the patient begins to complain about diplopia. Normally, the nearest convergence point should be less than 10 cm.

Nearest point of accommodation

This is the point at which the binocular clarity of the image is preserved. It can also be evaluated using the RAF ruler. The patient fixes the stitch, which is then slowly moved proximally until it becomes defocused. The distance at which the image blurs, and determines the nearest accommodation point. The nearest convergence point with age is removed, and its significant removal is accompanied by difficulties in reading without adequate optical correction, which indicates presbyopia. At the age of 20, the nearest convergence point is 8 cm, and at the age of 50, it can be more than 46 cm.

Amplitude of fusi

It is a measure of the effectiveness of disjugate movements, it can be studied using prisms or synoptophor. The prisms of the growing force are placed in front of the eye, which passes into the state of abduction or adduction (depending on the base of the prism: inside or outside, respectively) to maintain the biphovel fixation. If the strength of the prism exceeds the fusional reserves, diplopia occurs or one eye deviates in the opposite direction. This is the limit of the ability to verge.

Fusional reserves should be assessed for each patient at risk of diplopia in the postoperative period.

Refraction and ophthalmoscopy

Ophthalmoscopy with a wide pupil is mandatory when examining a patient with strabismus to exclude pathology of the fundus, for example, macula scars, hypoplasia of the optic nerve disk or retinoblastoma. Strabismus can be a refractive genesis. Perhaps a combination of hypermetropia, astigmatism, anisometropia and myopia with strabismus.

[7], [8], [9], [10], [11]

Cycloplegia

The most common cause of strabismus is hypermetropia. For an accurate assessment of the degree of hypermetropia, a maximal paresis of the ciliary muscle (cycloplegia) is necessary to neutralize the accommodation masking the true refraction of the eye.

Cyclopentolate allows you to achieve adequate cycloplegia in most children. Up to 6 months of age, cyclopentolate should be used 0.5%, later - 1%. Two drops, dripped with an interval of 5 minutes, lead to a maximum ophthalmoplegia after 30 minutes, followed by recovery of accommodation in 24 hours. Adequacy of cycloplegia is checked with a scapacoscope when the patient fixes distant and near objects. With adequate cycloplegia, the differences will be minimal. If the difference still exists and cycloplegia does not reach its maximum, then wait 15 more minutes or install a drop of cyclopentolate additionally.

Local anesthesia, eg proximetacaine. It is advisable before instillation of cyclopentolate for the prevention of irritation and reflex lacrimation, which allows longer retention of cyclopentolate in the conjunctival cavity and achieve more efficient cycloplegia.

Atropine may be necessary in the treatment of children under the age of 4 with high hypermetropia or strongly pigmented irons, for which cyclopentolate may not be sufficient. It is easier to instill atropine in droplets, than to lay ointment. Atropine 0.5% is used in the treatment of children under 1 year and 1% - over 1 year. The maximum cycloplegia occurs after 3 hours, the accommodation begins to recover after 3 days and is completely restored after 10 days. Parents instill the child atropine 3 times a day for 3 days before the skiascopia. It is necessary to stop the installation and seek medical help at the first signs of systemic intoxication, tides of crayfish, fever or anxiety.

[12], [13], [14], [15], [16], [17], [18],

When to write glasses?

Any significant anomaly of refraction should be corrected, especially in patients with anisotropism or aniso-astigmatism accompanied by amblyopia.

1. Hypermetropia. The minimum hypermetropic correction depends on the age and position of the eyes. In the absence of esotropia in a child under 2 years of age, the minimum correction is +4 dptr, although in older children it makes sense to correct hypermetropia and +2 Dpt. However, in the presence of esotropia, it is necessary to correct the hypermetropia to +2 D, even at the age of 2 years.
2. Astigmatism. It is necessary to assign cylindrical glasses with a force of 1 dpt and more, especially with anisometropia.
3. Myopia. The need for correction depends on the age of the child. Up to 2 years, it is recommended to correct myopia -5 dptr and more. From 2 to 4 years, it is recommended to correct -3 dptr, and older children - and a lower degree of myopia, to ensure a clear fixation of the distant object.

Change in refraction

As refraction changes with age, the examination is recommended to be carried out every six months. Most babies are born with hypermetropia. After 2 years, the degree of hypermetry may increase, and astigmatism - decrease. Hypermetropia can grow up to 6 years, and then (between 6 and 8 years) gradually decrease until adolescence. Children under 6 years of age with hypermetropia less than +2.5 Dptr at the age of 14 become emmetrops. However, with esotropia at the age of 6 years with a refraction of more than +4.0 liters, the probability of reducing the degree of hypermetropia is so low that without glasses, the correct position of the eyes is not achieved.

[19], [20], [21], [22], [23]

Diplomacy research

The Hess test and the Lees screen allow to depict the position of the eyeballs depending on the function of the extraocular muscles and allows to differentiate the paretic strabismus of the neurophthalmic nature from restrictive myopathy in endocrine ophthalmopathy or fracture fractures of the orbit.

Hess test

The screen is a tangential grid applied to a dark gray background. A red flashlight, which can illuminate each object separately, allows you to identify each extraocular muscle in different positions of the eye.

1. The patient is seated in front of the screen at a distance of 50 cm, put on red-green glasses (red glass - in front of the right eye) and give a green "laser" pointer.
2. The researcher projects a vertical red slit from the red "laser" pointer to the screen, which serves as a fixing point. This is visible only to the right eye, which thus becomes fixative.
3. The patient is asked to put a horizontal slit of the green lamp on the vertical red slit.
4. In orthophoria, two cracks are roughly superimposed on each other in all positions of the gaze.
5. Then glasses are turned over (red filter in front of the left eye) and the procedure is repeated.
6. The points are connected by straight lines.

Lees screen

The device consists of two screens of frosted glass, located at right angles to each other and divided in half by a two-way flat mirror that separates the two visual fields. The back of each screen has a mesh that is visible only if the screen is illuminated. The test is carried out with the fixation of the eye with each eye separately.

1. The patient sits in front of the unlit screen and fixes the points in the mirror.
2. The examiner indicates the point that the patient should mark.
3. The patient points with a pointer on the unlit screen, which he perceives next to the point shown to the examiner.
4. When all the points are applied, the patient is seated before another screen and the procedure is repeated.

Interpretation

1. Compare the two schemes.
2. The contraction of the pattern indicates paresis of the muscle (right eye).
3. Expansion of the scheme - the hyperfunction of the muscle of the eye (left eye).
4. The largest reduction in the scheme indicates the main direction of action of the paralyzed muscle (the external muscle of the right eye).
5. The greatest expansion of the muscle - the main direction of the action of the paired muscle (the internal rectus muscle of the left eye).

Changes in time

Time changes serve as a prediction criterion. For example, with the paresis of the upper rectus muscle of the right eye, the Hess test pattern indicates the hypofunction of the affected muscle and the hyperfunction of the paired muscle (the left lower braid). Due to the difference in the patterns, the diagnosis is unquestionable. If the function of the paralyzed muscle is restored, then both circuits return to normal. However, when saving a paresis, the form of the schemes can be changed as follows:

• The secondary contracture of the ipsilateral antagonist (the lower rectus of the right eye) appears on the diagram as a hyperfunction, which leads to a secondary (inhibitory) paresis of the paired muscle antagonist (left upper oblique), which looks like hypofunction on the diagram. This can lead to the wrong conclusion that the lesion of the upper oblique muscle of the left eye is primary.
• Over time, the two schemes become more and more similar as long as the detection of the paralyzed muscle becomes impossible.

[24], [25], [26]