Acute-onset esotropia (ET) is a rare presentation of Chiari I malformation. The ET may resolve following neurosurgical decompression, although this is not usually immediate.¹ Where neurosurgery is not undertaken, Kowal et al² suggest prismatic correction or strabismus surgery. The latter may result in temporary correction of the strabismus, as the strabismus can recur and resolves only following decompression.³ Botulinum toxin (BT) has been reported as successful in one case where the ET did not resolve following neurosurgery.⁴ Despite BT being a common treatment for acute acquired concomitant ET,⁵ no previous case has been reported in which BT …