Nystagmus in children

Nystagmus is a rhythmic oscillatory movement of one or both eyes around one or more axes. The movements can be pendulum-like (rhythmic) or jerky (with oscillation phases of different speeds).

Nystagmus is a complex form of pathology and is quite often a clinical and anatomical cause of low vision. The incidence of nystagmus, according to various authors, ranges from 1 in 5,000 to 1 in 20,000 of the population. During examinations of students in schools for the visually impaired, nystagmus was detected in 6-44%. Thus, despite the relative rarity of nystagmus, it often accompanies low visual acuity and can be both its cause and consequence.

Healthy people may experience physiological nystagmus when looking at fast-moving objects (railway or optokinetic nystagmus), with irritation of the labyrinth of the middle ear (labyrinth or vestibular). Nystagmoid twitching occurs normally and with prolonged extreme abduction of the eyes due to fatigue of the external muscles of the eye. Pathological nystagmus is a diagnostic problem for ophthalmologists, otolaryngologists, neurologists and neurosurgeons, since it can be central (neurogenic), peripheral (labyrinth or vestibular), ocular (fixation), can occur due to professional activity (in a miner), after intoxication (drug, alcohol). Consequently, nystagmus can be a symptom that allows one to suspect and identify pathology of the middle ear or brain structures. In such cases, treatment of the underlying disease is necessary. Nystagmus can also become the main disease in pathology of the visual-nerve and oculomotor apparatus, then the task of patient rehabilitation is faced by ophthalmologists.

Pathological nystagmus is caused by a disorder of the visual fixation mechanism and occurs with its congenital pathology, transmitted by inheritance, or as a result of acquired lesions of various parts of the brain that regulate micromovements of the eyes. The following types of pathological nystagmus can be distinguished: neurogenic, congenital, early acquired, latent, manifest-latent, nystagmus in albinism, nystagmus caused by drugs, alcoholic nystagmus.

Neurogenic (central) nystagmus occurs as a result of inflammatory, degenerative, tumor and traumatic lesions of various parts of the central nervous system that control movements (with lesions in the area of the posterior cranial fossa, cerebellum, vestibular nuclei, medial longitudinal fasciculus, subcortical and cortical centers regulating eye movements). Manifestations of neurogenic nystagmus depend on the dynamics of the underlying disease.

Vestibular pathological nystagmus, unlike physiological vestibular, which is reflex, induced, is always spontaneous and is caused by a disorder of the central vestibular function or a disease of the peripheral vestibular apparatus. This type of nystagmus is usually combined with dizziness and nausea.

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Congenital and early acquired nystagmus

Congenital and early acquired nystagmus occurs with congenital pathology of the oculomotor apparatus (cataract, corneal opacities, optic nerve atrophy, etc.), is transmitted hereditarily or accompanies congenital and early acquired eye diseases. Oscillatory eye movements with this nystagmus are caused by a disorder of visual fixation due to a violation of the regulatory mechanism or a defect of central vision.

Unlike congenital nystagmus, in which the patient does not notice the oscillatory movements of the eyes, with early acquired nystagmus they are noticeable.

Treatment of congenital and early acquired nystagmus is aimed at reducing its amplitude, improving visual functions and visual performance. It includes optical correction of ametropia, prismatic correction, pleoptics (exercises to improve visual acuity), impact on the accommodation apparatus, drug treatment, exercises based on the principle of biological feedback and operations on the oculomotor muscles. In most cases, such treatment is effective. The use of glasses with protective spectral filters (in case of a combination of nystagmus with albinism, diseases of the macular region, aphakia) improves visual acuity.

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Latent and manifest-latent nystagmus in children

Latent nystagmus is a binocular nystagmus that occurs when one eye is switched off from the act of vision. With both eyes open and when both eyes are switched off, such nystagmus does not appear. Sometimes latent nystagmus occurs only when a certain eye is switched off, usually the leading one with better vision. And when the other eye is switched off, there is no nystagmus.

With both eyes open, visual acuity is high or normal, and with vision in one eye, due to latent nystagmus, it is reduced to one degree or another. This type of nystagmus is present from birth and remains unchanged throughout life. It should be considered conditionally pathological; it does not require special treatment.

With a sharp decrease in visual acuity in one eye due to anatomical causes or amblyopia, as well as suppression of visual impressions in the squinting eye, with strabismus, the latent form of nystagmus takes the form of manifest-latent nystagmus. As a rule, manifest-latent nystagmus is accompanied by concomitant strabismus. Treatment of manifest-latent nystagmus often requires the elimination of strabismus and amblyopia, as well as a slightly different tactic of surgical intervention on the oculomotor muscles

Nystagmus in albinism

Albinism is based on a disorder in the formation of the pigment melanin from tyrosine. The absence of pigment in the skin, hair and eye membranes is a congenital defect inherited primarily in an autosomal recessive manner.

The ocular manifestations of albinism are varied: photophobia, changes in colour and atrophy of the iris, reddish glow of the pupil and iris (the red reflex from the fundus penetrates through defects of the iris), the fundus is pale pink, the vascular pattern of the choroid is clearly visible. Visual acuity is reduced mainly due to hypoplasia or aplasia of the macula, colour blindness is often present.

Treatment of nystagmus in albinism is the same as for congenital nystagmus. Wearing light-protective or pinhole glasses and dark contact lenses with a transparent center is recommended.

Drug-induced nystagmus in children

The use of certain medications (barbiturates, phenothiazines, tranquilizers, anticonvulsants, etc.), especially in large doses, can cause nystagmus. A combination of nystagmus with dizziness, ataxia, dysarthria and other disorders is possible, especially in acute intoxication. If nystagmus of this nature is suspected, a detailed questioning and examination for the presence of drugs, as well as determination of their concentration in the blood, are necessary. Drugs causing nystagmus should be discontinued, their dose should be reduced or other drugs should be used. A set of functional methods aimed at restoring visual functions, and finally, surgical intervention on the oculomotor muscles significantly expand the treatment options for this serious disease, previously considered incurable.