Therapeutic options in ocular myasthenia gravis

Abstract

The term ocular myasthenia gravis refers to the disease clinically restricted to extrinsic ocular muscles. It can be disabling as ptosis, and to a greater extent diplopia, both interfere with daily activities. Although ocular disturbances are the most frequent initial complaints in myasthenic patients, symptoms usually progress to generalized disease and only 15% of patients complain of purely ocular weakness for the entire course of their illness. Secondary generalization occurs with the highest frequency in the first 2 years from the onset. Both the severity of symptoms and the risk of generalization should be taken into account when devising a therapeutic plan for these patients. Anticholinesterases are of limited efficacy and a considerable proportion of patients require additional therapy. Corticosteroid therapy, generally prednisone on an alternate-day schedule, is very effective, but a reason for concern is represented by the frequent need for long-term administration with increased risk of severe complications. In patients unresponsive to prednisone or requiring too high dosages, immunosuppressive drugs like azathioprine should be used with the same criteria applied in generalized myasthenia. As corticosteroids and immunosuppressants reduce the chance of generalization, their use is justified in patients with recent-onset disabling disease. In long-standing cases with low risk of generalization, treatment is aimed at the relief of symptoms and pharmacological therapy should be reduced to the minimum effective dosage. The indication for thymectomy in ocular myasthenia remains highly controversial and should be reserved for disabled patients in the early stages of the disease.