Question category: Ophthalmology
A 30-year-old presents to her GP with reduced vision in her left eye. She has previously presented with abnormal sensory changes in her leg which have now resolved. On examination her visual acuity is greatly reduced and there is evdence of a relevant afferent pupil defect. All movements of the eye are very painful. On fundoscopy and neurological examination there is nil of note. What is the most likely diagnosis?