Criteria for diagnosing ocular myasthenia gravis
| (1) Ptosis in one or both upper lids not due to local lid disease, preferably that could fatigue or recover with rest. |
| (2) Extraocular muscle weakness in one or both eyes not in a strict third nerve muscle innervation pattern. If solely lateral rectus weakness, clearcut fatiguability, recovery, or positive edrophonium test. |
| (3) Weakness can be present in one or both orbicularis oculi but no other weakness of the muscles of the head and neck. |
| (4) No pupillary abnormality other than from previous local disease or surgery. |
| (5) (A) plus (B), or (C) or (D) or (E) has to be present: |
| (A) Fatigue of the affected muscle with clear cut worsening of the ptosis after upward gaze for 30 to 60 seconds or worsening of the monocular duction after 120 seconds of gaze in the direction of action. |
| (B) Recovery of the upper lid ptosis to almost normal after 30 seconds to 10 minutes of eyelid closure. Recovery of the monocular duction after 120–180 seconds of gaze in the direction of the antagonist muscle. |
| (C) A positive edrophonium test |
| (D) Abnormal repetitive stimulation electromyography with a minimum decrement of 10%. |
| (E) Abnormal serum acetylcholine receptor binding level. |