OP10.2 | Heterotropia and Strabismus — Summary & Reflection

KEY TAKEAWAYS

Strabismus — Key Points:

• Strabismus is classified by direction (eso/exo/hyper), laterality (unilateral/alternating), comitance, onset, and accommodative status.
• Comitant strabismus: angle equal in all gazes, full ductions, childhood onset, no diplopia (suppression/amblyopia risk). Predominant types: infantile esotropia (large angle, alternating, surgical), accommodative esotropia (hypermetropia, resolves with glasses), intermittent exotropia.
• Incomitant strabismus: angle varies with gaze, limited ductions, diplopia. Caused by CN palsies (VI = abduction failure, IV = depression-in-adduction failure + head tilt, III = 'down and out' ± pupil) or mechanical restriction.
• Pseudostrabismus: symmetric Hirschberg reflex, negative cover test — epicanthal folds or positive angle kappa mimicking esotropia. Reassure; no treatment.
• Amblyopia: reduced VA in the deviated eye not correctable by spectacles; treat before age 7–8 (critical period); mainstay = patching of the better eye.
• Cycloplegic refraction is mandatory in all children with strabismus — atropine or cyclopentolate.
• Management sequence: refractive correction → amblyopia therapy → strabismus surgery (if residual).
• Referral: any child with suspected strabismus; any adult with new-onset diplopia; any strabismus with systemic features.

REFLECT

Think about the child from the hook scenario — whose strabismus had been 'watched' for six months. What would the consequence have been if assessment and amblyopia treatment had been delayed until age 10? At what point in the 'watch and wait' period was the child's visual system silently losing the battle against amblyopia? As you progress through your ophthalmology training, make it a habit to examine the visual acuity of each eye separately in every child — even a child brought in for something else entirely. A child with amblyopia does not complain because they have never known better vision; only a systematic examination will catch it.