Autoimmune myasthenia gravis (MG) frequently involves the extrinsic ocular muscles (EOM) and
the disease clinically restricted to the EOM is referred to as ocular myasthenia (OMG). It has been reported
that approximately 50% of patients presenting with OMG subsequently progress to develop
generalized disease, usually within the first one to two years. Several clinical and laboratory factors,
such as older age at onset, presence of anti-acetylcholine receptor (AChR) antibody, high antibody titers,
and the presence of thymoma, have been claimed to predict the risk for secondary generalization.
As for the treatment of OMG, early immunosuppressive therapy, specifically corticosteroids, has been
suggested to prevent or delay the progression into generalized disease, although the cost-to-benefit
ratio of this treatment remains controversial with no randomized controlled study conducted so far.
There is mounting epidemilogical evidence of ethnic difference in clinical manifestation of MG, particularly
between Caucasians and Asians. Asians appears to have an earlier childhood onset, higher
prevalence of OMG, and lower titers of AChR antibody. This article should be focused on OMG, particularly
regarding its definition, natural course, diagnostic and therapeutic challenges. Also it will be covered
why EOM is susceptible to MG.

KEYWORDS : Ocular myasthenia gravis, Extraocular muscles