Can you shed some light on this patient’s blurred vision?

A dilated pupil and absent lower-limb reflexes point to an unusual diagnosis
Dr Grace Borchert Jessica Li Associate Professor Ian Francis

Morgan, a 38-year-old office worker, presents with a new dilated left pupil.

She reports that, in the past 24 hours, vision in her left eye has become blurred when reading, but distance vision has been unaffected.