27th June 2023

A 28-year-old female presents with a three-day history of loss of vision in her right eye. She describes waking up one morning and noticing a dull aching pain in her eye

A 28-year-old female presents with a three-day history of loss of vision in her right eye. She describes waking up one morning and noticing a dull aching pain in her eye with blurry vision which worsened over several hours before plateauing. Vision in her left eye is intact. On examination, she is able to count fingers with her right eye, and there is a relative afferent pupillary defect. Her neurological examination is otherwise normal.

She describes experiencing a similar episode 5 years ago, but it had resolved by the time she sought medical attention. She is otherwise fit and well, with no other past medical history.

Which of the following investigations should be performed in the first instance to aid the diagnosis of likely multiple sclerosis?