Author: Abdulmalik Alsaif / Editor: Sarah Edwards / Codes: OptP1, SLO1, SLO2 / Published: 07/11/2022

A 63-year-old female patient presents to her local emergency department (ED) with a four-day history of double vision. She denies any trauma, headache, vomiting or weakness. On questioning, she describes objects being ‘side by side’.

The patient has no previous medical history and is not taking any medications.

On examination she has right-eye esotropia, and her double vision disappears on closing either eye (Figure 1). The diplopia is worse at the right lateral gaze with restricted abduction of the right eye. Other extraocular movements are within normal limits. Fundoscopy, pupils, eyelids and other cranial nerve examinations are unremarkable and her visual acuity is 6/6 for both eyes.

Observations: Blood pressure 162/93 mmHg, pulse was regular at 85 bpm.