Makindo Medical Notes

👁️ Strabismus (Squint) = ocular misalignment. In children, if untreated, it leads to amblyopia (lazy eye) because the brain suppresses the deviating eye. 👉 Any persistent squint beyond 3 months of age needs ophthalmology referral.

📍 About

• Strabismus = inability to align both eyes simultaneously under normal viewing conditions.
• One or both eyes may deviate inwards (esotropia), outwards (exotropia), upwards or downwards.
• Untreated → suppression of one eye by the brain → abnormal visual pathway development → amblyopia (functional blindness in the affected eye).

🧬 Aetiology

• Visual system develops until ~8 years → requires congruent images from both eyes.
• If images differ, the brain suppresses the deviating eye.
• Suppression → underdeveloped optic pathways → irreversible amblyopia if untreated.

⚠️ Risk Factors

• Family history of strabismus.
• Refractive error: uncorrected hyperopia (farsightedness).
• Medical conditions: Down syndrome, cerebral palsy, perinatal brain injury, stroke, or head trauma.

🔎 Causes

Strabismus can be congenital or acquired. Key types include:

• Congenital (Infantile) Esotropia: Presents within 6 months; inward turning of one/both eyes; risk of amblyopia.
• Accommodative Esotropia: Ages 2–4; hypermetropia → excessive focusing effort; improves with glasses.
• Intermittent Exotropia: Eye drifts out, esp. when tired; may close one eye in sunlight.
• Nerve Palsies (CN III, IV, VI): Sudden onset misalignment + diplopia; neurological cause until proven otherwise.
• Restrictive: Thyroid eye disease, trauma, scarring.
• Duane Retraction Syndrome: Congenital; absent CN VI; retraction of globe on attempted abduction.
• Convergence Insufficiency: Difficulty with near tasks, headaches, double vision.
• Trauma: Muscle entrapment or nerve injury → diplopia.
• Neurological: MS, stroke, tumour → urgent neuroimaging.

🩺 Clinical Assessment

• Cover–uncover test: Gold standard for detecting latent/manifest squint.
• Document visual acuity in each eye separately.
• Note if worse when tired, ill, or after prolonged near work.
• Screening is essential in children (esp. school vision checks).

💊 Management

• Correct refractive error: Glasses or contact lenses.
• Prism lenses: Reduce eye strain and realign image.
• Occlusion therapy: Cover the good eye → force use of the lazy eye → prevent amblyopia.
• Vision therapy: Exercises to improve coordination and fusion.
• Surgery: Eye muscle surgery (recession/resection) for persistent squint; often combined with vision therapy afterwards.

📚 References

• American Academy of Ophthalmology – Strabismus Guidelines
• NICE CKS – Childhood vision problems

📌 Exam Tip

👶 Any constant squint >3 months in a child = urgent referral.
🔑 Infantile esotropia: early, constant, inward squint.
🔑 Accommodative esotropia: age 2–4, improves with glasses.
🚨 Acute onset strabismus + diplopia in an adult = think CN palsy → neuroimaging.