Ocular myasthenia gravis is an autoimmune process that blocks the communication between normally functioning muscles of the eyes and the nerves that signal to them. Patients with this condition will notice drooping of the eyelids and double vision that can fluctuate throughout the day; the symptoms worsen as the day goes on or with use of the eyes, but can improve with rest.
Myasthenia gravis can also affect the rest of the body, causing muscle weakness of the arms and legs, difficulty swallowing, difficulty breathing, and difficulty speaking. About 85% of patients who present with only ocular myasthenia graves will develop symptoms in other parts of the body within 2 years. Usually, after that time period, generalized myasthenia is unlikely to develop.
If ocular myasthenia gravis is suspected, patients will undergo a complete eye examination. In addition, blood work will be obtained to check for the antibodies associated with myasthenia gravis. In about 50% of patients, the results may be falsely negative. Thus, if the suspicion for ocular myasthenia is still high, additional testing can be performed, including injection of a medication to see if the symptoms of ocular myasthenia gravis will temporarily go away for a few seconds while the medication is in the bloodstream. Or, an electromyogram test that measures a muscle’s response to electrical stimulation can be performed.
Once the diagnosis is made, additional care from a neurologist will be required in order to medically treat and monitor the condition. A chest CT may also be ordered to look for a benign tumor called a thymoma, which when removed could improve the symptoms of myasthenia gravis. In some cases, if the double vision does not go away with medical treatment, special glasses with prisms would be prescribed.