Myasthenia gravis is an autoimmune disorder of neuromuscular junction transmission. It is relatively rare, with an approximate annual incidence of 1 per 100,000 population, and prevalence of 15 per 100,000 population in the UK. An ocular presentation may include fatiguing ptosis or diplopia. Typically, symptoms ‘fatigue’ (the physical power of the muscle deteriorates rapidly with repeated activity) and become more noticeable as the day progresses. More generalised symptoms include fatiguing difficulty with speech or swallowing. There may be fatiguing weakness of the arms and legs. The diagnosis will usually be confirmed by referral to a neurologist.