Strabismus

What is Strabismus?
Strabismus is a condition where the eyes lose parallelism in their line of sight, causing them to drift. Although it is more commonly seen in childhood, strabismus can also develop in adults due to various causes.

What are the Symptoms Associated with Strabismus?
The eye misalignment can occur in various directions, but it most commonly involves inward (esotropia) or outward (exotropia) deviation. Some additional signs that can accompany strabismus include limited eye movement in certain directions, drooping eyelids, involuntary eye jerks (nystagmus), turning the head or face to one side, refractive errors, and amblyopia (lazy eye). Conditions like corneal opacity, cataracts, vitreous diseases, or retinal diseases that impair vision can also lead to strabismus.

What is Pseudo-Strabismus?
Pseudo-strabismus refers to a condition where a child’s eyes appear misaligned, but there is no actual misalignment. This can happen due to a wide nasal bridge, epicanthal folds (skin folds at the inner corner of the eye), or a large distance between the eyes, giving the illusion of strabismus. In these cases, strabismus is not present and typically resolves as the child grows older and facial bones develop. A thorough examination by an eye doctor can easily differentiate between true strabismus and pseudo-strabismus.

How is Strabismus Classified?
Strabismus is generally classified based on the direction of the eye misalignment:

• Esotropia (Inward Deviation)
• Exotropia (Outward Deviation)

Esotropia (Inward Deviation): Causes and Treatment
In children, esotropia often occurs when one or both eyes turn inward. It usually appears around the age of two, but can develop at any age between 6 months and 7 years. This condition is often associated with hypermetropia (farsightedness), and correcting the refractive error with glasses can help realign the eyes. If strabismus persists despite glasses correction, surgery may be required.

Another form of esotropia is infantile esotropia, which appears within the first six months of life, often with significant misalignment. Early treatment, including glasses for refractive errors and surgery if necessary, is crucial to correct the condition before the child turns 2 years old.

Exotropia (Outward Deviation): Causes and Treatment
Exotropia can be either constant (always present) or intermittent (appears occasionally).

• Constant Exotropia: This can be present from birth and does not respond to glasses correction. Surgical intervention is necessary to correct the alignment.

• Intermittent Exotropia: This form usually appears around age 2 and is more noticeable in certain conditions, such as fatigue, stress, or poor health. It often becomes more prominent during the day. In cases where refractive errors like myopia are present, correcting them with glasses may reduce the strabismus. If the misalignment persists, surgery may be required around the age of 5.

Exotropia can also develop in children older than 5 or in adults due to conditions like cataracts, corneal opacities, or eye trauma. In such cases, treating the underlying condition is necessary, followed by addressing any resulting amblyopia (lazy eye).

General Treatment Principles for Strabismus

1. Comprehensive Eye Examination: A complete eye examination is necessary to determine the type of strabismus, the degree of misalignment (measured with prism tests), and to rule out any conditions such as corneal opacity, cataracts, or retinal disease that could impair vision.

2. Surgical Intervention in Early Childhood: If strabismus appears within the first 6 months of life and no significant refractive errors are present, early surgery is often needed to correct the misalignment and prevent amblyopia (lazy eye).

3. Correcting Refractive Errors: If strabismus is related to refractive errors (e.g., hypermetropia), providing appropriate corrective lenses (glasses) is the first step in treatment. In cases where amblyopia is present, occlusion therapy (covering the stronger eye) is used to improve vision in the affected eye.

4. Surgical Intervention in Older Children and Adults: For strabismus that develops or persists into later childhood or adulthood, surgery may be required. However, post-surgical double vision (diplopia) can occur, especially in adults who have not been treated during childhood. Double vision can persist for several months, and additional treatments may be necessary to realign the eyes fully.

Early treatment of strabismus, particularly in childhood, significantly improves outcomes by preventing long-term visual issues like amblyopia and improving the depth perception and alignment of the eyes.