What could be underlying this partial ptosis?

With a wide variety of clinical signs and symptoms, it is important to keep an eye out for this elusive automimmune disease

Max is a 54-year-old maintenance worker who presents with a two-month history of a drooping right eyelid.

checking pupils

This is intermittent and does not have clear features of fatigability.

When symptomatic, Max describes having to tilt his head backwards in order to focus his vision.

There is no pain, visual acuity is otherwise unaffected and there are no other associated visual symptoms.

He has a past history of factor V Leiden mutation, diagnosed several years ago after he had two unprovoked DVTs, for which he takes