A 25 year old registered nurse presents to her GP with a 6 day history of abnormal vision, which she noticed whilst checking her blind-spot when driving. This has been accompanied by painful extraocular movements & the sensation that her right eyelid was drooping. She has had a recent viral URTI & has been quite stressed at work with a pending presentation and upcoming exams….
She has been referred to your ED today (by the Ophthalmologist) with the following visual field examination
** hence the "droopy eyelid" **
On examination, her pupils are equal & reactive directly, but there is a positive Marcus-Gunn reflex on the right side. VA 6/5 on (L) & 6/18 on (R). Normal EOM, but reports pain in the right eye with lateral gaze (“like a tight cord pulling”).
She is holding a letter from the Ophthalmologist which states, “please start treatment!”
What’s the diagnosis ?
What are we treating & why ??