Ptosis and diplopia are the most frequent initial clinical signs in patients with myasthenia gravis. Both are intermittent and fluctuating, but also characterized by greater disability on use. Recovery, partially or totally, takes place after rest. The symptoms are likely to be more disabling at the end of the day. Myasthenia gravis usually progresses by periods of remission and relapse, so that ocular signs may disappear without known cause for months or even years.
These unique qualities of muscular weakness, only found in myasthenia gravis, make the diagnosis, provided the ophthalmologist has the disease in mind, both easy and certain in most patients. Until comparatively recently, however, many patients remained undiagnosed for years, often considered as showing signs of some intracranial, structural disease. Only when muscular weakness developed in other muscles, such as those used for swallowing, talking, or locomotion, were ptosis and diplopia thought of as manifestations of a
Henry R. Viets. The Miracle at St. Alfege's. Arch Ophthalmol. 1965;73(4):462. doi:10.1001/archopht.1965.00970030464002