Types of strabismus
The movements of each eye are provided by six muscles, the work of which is coordinated by the brain. With concomitant strabismus, the muscles and nerves are normal, but joint control is impaired, and the angle of deviation is the same when looking in different directions. Paralytic strabismus occurs when a nerve or muscle is damaged: the eye is limited in movement, double vision appears. The direction is divided into convergent, divergent and vertical. Separately, false strabismus is distinguished in children with a wide bridge of the nose and folds of skin at the inner corner of the eyes - upon examination, the eyes are positioned correctly.
- Convergent - the eye deviates towards the nose
- Divergent - the eye deviates towards the temple
- Vertical - up or down
- Friendly and paralytic
- Constant and periodic
- Accommodative – associated with farsightedness
- False strabismus in infants
Causes and risk factors
In newborns, the eyes may periodically diverge or converge for up to 3–4 months while vision is developing. If the deviation persists later, an inspection is needed. In children, a common cause of convergent strabismus is uncorrected farsightedness: in order to see clearly, the child greatly strains accommodation, and the eyes narrow. Strabismus is more common in premature babies, with cerebral palsy, genetic syndromes, and also with decreased vision in one eye due to cataracts or retinal diseases. In adults, the causes include stroke, diabetes, trauma, thyroid disease, myasthenia gravis, and tumors.
- Farsightedness and astigmatism
- Heredity
- Prematurity and cerebral palsy
- Low vision in one eye
- Head and eye socket injuries
- Diabetes mellitus and vascular diseases
- Thyroid diseases and myasthenia gravis
Symptoms
The main sign is a visible deviation of one eye, which is noticed by parents or others. Sometimes one or the other eye squints. The child may squint or close their eyes to the sun, or tilt or turn their head to reduce the deviation. Children rarely complain of double vision, as the brain quickly suppresses the image of a squinting eye, which leads to amblyopia. Adults, on the contrary, with acute strabismus experience painful double vision, dizziness, and difficulty assessing distance. Periodic strabismus usually worsens with fatigue, illness and in the evening.
- Eye deviation to the side
- Squinting or closing one eye
- Tilt or turn your head
- Double vision - more common in adults
- Decreased vision of a squinting eye
- Three-dimensional vision impairment
- Eye fatigue
Diagnostics
The ophthalmologist finds out when strabismus appeared, whether relatives have it, and studies photographs of the child. The cover test can reveal even small hidden deviations, and the angle of strabismus is measured using prisms. Be sure to determine the refraction after instillation of cycloplegic drops, check the visual acuity of each eye, the range of eye movements and binocular vision. Fundus examination excludes diseases of the retina and optic nerve. Adults with acute paralytic strabismus are prescribed a consultation with a neurologist, an MRI or CT scan of the brain, and an analysis of glucose and thyroid hormones.
- Cover test
- Measuring the strabismus angle with prisms
- Refractometry with cycloplegia
- Checking visual acuity in each eye
- Study of eye mobility and binocular vision
- Fundus examination
- MRI of the brain for paralytic strabismus
Treatment
Treatment begins with full spectacle correction: with accommodative strabismus, farsightedness glasses can completely straighten the eyes. At the same time, amblyopia is treated by gluing the better-seeing eye. Orthoptic and binocular exercises help restore joint function of the eyes. If the deviation persists with glasses, surgery is performed on the extraocular muscles: the surgeon weakens or strengthens certain muscles, changing the position of the eye. The operation does not replace glasses or treatment for amblyopia. For adults with double vision, prismatic glasses are selected, and sometimes botulinum toxin injections are used into the muscles.
- Glasses for constant wear
- Occlusion in amblyopia
- Orthoptic and binocular exercises
- Surgery on the extraocular muscles
- Prismatic glasses for double vision
- Botulinum toxin injections according to indications
- Treatment of the underlying disease in adults
