Acute Careniche
A 74-year-old woman describes losing the sight of her right eye over a few seconds while watching television 90 minutes ago. It has not come back and she now sees only hand movements with that eye. The right pupil barely constricts when the light is shone into it but constricts briskly when the left eye is lit. The retina looks pale and the centre of the macula stands out red. Her pulse is irregular at 96/min. She has no headache, scalp tenderness or jaw ache, and the temporal arteries are not tender. Which one of the following should the emergency registrar do first?