Strabismus (Eye Squint)

Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management | References

Definition

Strabismus, commonly known as a squint, is a condition where the eyes do not align properly. One eye may look straight ahead while the other eye turns inward, outward, upward, or downward. This misalignment can be constant or intermittent.

Aetiology

Strabismus can be caused by various factors, including:

• Refractive errors such as uncorrected long-sightedness
• Imbalance in the muscles that control eye movement
• Genetic predisposition
• Medical conditions such as cerebral palsy or Down syndrome
• Trauma or injury to the eye muscles

Pathophysiology

The misalignment in strabismus occurs due to the inability of the eye muscles to work together properly. This can result from differences in muscle strength, nerve control, or structural abnormalities in the eye or brain. The brain may suppress the image from the misaligned eye to avoid double vision, leading to amblyopia (lazy eye) if untreated.

Risk Factors

• Family history of strabismus
• Uncorrected refractive errors
• Neurological or developmental disorders
• Premature birth or low birth weight
• Conditions like cerebral palsy or Down syndrome
• Previous eye surgery or trauma

Signs and Symptoms

Common signs and symptoms of strabismus include:

• Eyes that do not move together
• Double vision
• Difficulty with depth perception
• Head tilting or turning to use the eyes together
• Eye strain or headaches

Investigations

• Clinical history and physical examination
• Ophthalmic examination including visual acuity testing
• Assessment by an orthoptist to evaluate eye movement and alignment
• Refraction test to check for refractive errors
• Neurological examination if an underlying condition is suspected

Management

Primary Care Management

• Referral to an ophthalmologist: For detailed assessment and management plan
• Corrective lenses: Prescription glasses or contact lenses to address refractive errors
• Patch therapy: Covering the stronger eye to improve the weaker eye's function, especially in children with amblyopia

Specialist Management

• Eye muscle exercises: To improve coordination and control of eye movements
• Botulinum toxin injections: To temporarily weaken overactive eye muscles
• Surgical intervention: Strabismus surgery to correct muscle imbalances by repositioning or shortening the eye muscles
• Regular follow-up to monitor progress and adjust treatment as necessary

References

1. Moorfields Eye Hospital. (2024). Strabismus (Eye Squint). Retrieved from Moorfields Eye Hospital
2. NHS. (2023). Strabismus. Retrieved from NHS
3. British Medical Journal (BMJ). (2022). Strabismus: Diagnosis and Management. Retrieved from BMJ

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