Author: Soma Farag / Editor: Sarah Edwards / Codes: OptC2, SLO1 / Published: 14/11/2022

A 62-year-old male with type two diabetes mellitus presents to the Emergency Department (ED)  complaining of sudden drooping and double vision in his right eye. He denies any headache or recent injury. He denies any flashes or floaters, eye discomfort or pain.


He has no significant family history.

Medications: Lisinopril, Metformin, Simvastatin.

On examination, the pupil of his right eye has a slower reaction to direct light and measures at 5mm, compared with 3mm in his left eye with a normal reaction to light.

The patient’s visual acuity is 20/20 in both eyes.

Cover test shows the patient could not adduct (Fig 1a), supraduct (Fig 1b) or infraduct (Fig 1c) his right eye. However, he could perform lateral rotation, depression and abduction of the right eye. He has full range of motility in his left eye.

Fundoscopy examination of both eyes is grossly normal with no obvious signs of diabetic retinopathy.

There was no evidence of sensory or motor impairment and the remainder of his cranial nerve examination is unremarkable.

A series of blood tests shows a HbA1c of 83mmol/mol.