Anisocoria constitutes an increasing proportion of referrals in paediatric ophthalmology. Up to 19.1% of children can have an anisocoria of >0.4 mm.1 Although isolated anisocoria in children is commonly physiological, Horner Syndrome is an important differential.2, 3 The unclear evaluation pathway of paediatric anisocoria results in a high volume of unnecessary neuroimaging.