Introduction:
Strabismus is a common eye condition in children, characterized by misalignment of the eyes. The eyes may point in opposite or different directions, with one eye looking straight and the other turning up, down, or sideways. The misalignment can shift from one eye to the other. Strabismus affects approximately 2 to 4 % of the population and can manifest as esotropia (inward deviation), exotropia (outward deviation), hypertropia (upward deviation), or hypotropia (downward deviation) in one or both eyes. It can be present from birth or acquired later in life due to trauma, accidents, or underlying health issues. Strabismus can be intermittent or permanent.
What Is Pediatric Strabismus?
Pediatric strabismus refers to the misalignment of the eyes, resulting in a deviation from normal gaze parallelism. It is a common eye condition in children, where the eyes cross or point in different directions. One eye may look straight, while the other may look sideways, downward, or upward. The movement of the eye is controlled by six muscles: one for moving the eye to the right, one for moving it to the left, and the remaining four for moving it upward, downward, and at an angle. All six muscles need to work together when focusing on a specific image. Strabismus affects vision, as both eyes must aim at the same spot for clear vision. If a child's eyes are properly aligned during childhood, their vision will develop well. However, misaligned eyes can lead to amblyopia or lazy eye, where one eye has weaker vision due to a lack of synchronization between the brain and the eyes. Strabismus, or squint, is commonly observed in children, affecting approximately 2 to 4 % of them. One eye may look directly at an object while the other eye deviates. The deviating eye may turn inward, outward, upward, or downward. Some cases of strabismus are mild and not permanent, occurring only when the person is tired, looking in a particular direction, or closing their eyes. In other cases, strabismus is present all the time. The condition can also be seen in babies. Strabismus generally develops before age 3, but it can also occur in older children and adults. If left untreated, strabismus can lead to amblyopia, causing permanent vision loss in the affected eye. Early treatment is crucial to prevent this.
What Causes Strabismus and What Are the Complications Arising From It?
Strabismus may cause the following complications:
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Half of the children having strabismus develop amblyopia (poor vision that generally develops in one eye and rarely in both eyes).
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Diplopia or double vision development is seen in cases with acquired strabismus in older children or adults.
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The appearance and function of the eyes may give rise to chaos in social and work life.
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The researchers and medical experts are not sure about the cause of strabismus but a few of the causes and risk factors are listed below:
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Duane syndrome (the sixth cranial nerve that controls the lateral rectus muscle is not developed or does not work properly).
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Moebius syndrome (a rare birth defect that affects the muscles controlling eye movements and facial expressions).
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Thyroid eye disease (it is an autoimmune disease in which the eye muscles and the fatty tissue behind the eye become inflamed).
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Cerebral injuries (brain injuries).
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Fracture of the orbital wall.
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Any nerve damage.
Risk factors:
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Presence of strabismus (a disorder in which both eyes do not line up in the same direction) in previous generations.
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Premature birth (birth before the ideal gestational period).
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Retinopathy (disease of the retina).
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Cataracts (cloudy area present in the eye).
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Severe ptosis (a condition when the upper eyelid droops down over the eye).
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Corneal scars (scars on the cornea).
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Muscular abnormalities.
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Neurological abnormalities.
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Amblyopia (poor vision that generally develops in one eye and rarely in both eyes).
What Is the Etiology of Strabismus?
The exact etiology is unknown, but fewer studies have been conducted, and certain causes have been stated. According to the studies conducted in many cases, strabismus is caused by the following points:
- Refractive error.
- Imbalance of muscles.
The rarest cause of strabismus can be retinoblastoma or any other serious ocular or neurological disease. Strabismus can be classified as infantile or acquired. The term "congenital" is not used, as true strabismus at birth is uncommon. Instead, "infantile" is used to describe all developments occurring within the first 6 months of life. "Acquired" encompasses developments occurring after the first 6 months. Risk factors for infantile strabismus include family history (first or second-degree relative), genetic disorders like Crouzon syndrome, prenatal drug or alcohol exposure, low birth weight or premature birth, congenital eye defects, and cerebral palsy. Acquired strabismus can develop suddenly and has various causes, including refractive error, tumors, head trauma, ocular or neurological conditions, and viral infections. The specific cause depends on the type and degree of deviation.
How Is Strabismus Diagnosed?
Strabismus is typically diagnosed during a general eye examination. Pediatricians should perform a thorough eye evaluation at each well-child visit. However, if a child exhibits symptoms of strabismus or any other eye condition, they should be referred to an ophthalmologist for a comprehensive eye examination. Various tests can help diagnose strabismus and associated conditions such as amblyopia. Light reflex testing assesses eye alignment by having the child focus on the point of light. Prisms may also be used to determine proper eye alignment. If a child is unable to communicate verbally, vision can be assessed by their ability to fixate on a moving object or their response when one eye is covered. Older children undergo standard eye examinations using letters or pictures to test their vision.
What Is the Treatment of Strabismus?
If strabismus is taken care of at an early stage, then the child will have a better chance of using eyes together and developing binocular vision and depth perception. Diagnosing and treating strabismus as early as possible is better to prevent amblyopia. Amblyopia may result in complete and permanent vision loss. For mild strabismus, glasses can be prescribed, or a patch can be given over the normally functioning eye. For severe strabismus, eye muscle surgery is recommended. Botox injections have been used in a few places to treat strabismus in children.
Conclusion:
Strabismus is when the eyes are misaligned. It commonly occurs in children in about 4 % of the population and is the reason for loss of vision in almost half of them. Most strabismus is caused by refractive error or muscle weakness, but sometimes a serious underlying disorder is the reason. Permanent and complete vision loss may occur if strabismus and associated amblyopia are left untreated. Treatment depends on the etiological factors, but sometimes the surgery becomes mandatory.
