Current treatment for ocular myasthenia gravis

Abstract

Myasthenia gravis (MG) is the most common neuromuscular junction disorder. Approximately 50% of patients with MG present with purely ocular symptoms, a condition referred to as ocular MG. Acetylcholinesterase inhibitors are often the first modality of the therapy for ocular MG. As an immune-mediated disorder, MG often responds to several immunosuppressive agents, such as corticosteroids or azathioprine. In patients with ptosis, simple ‘ptosis crutches’ can be helpful. However, in patients with ptosis refractory to appropriate medical therapy or in whom ptosis is the only finding, eyelid surgery may be necessary. For diplopia with a relatively stable angle of ocular deviation, prisms can be used. Strabismus surgery also can lead to satisfactory results in selected cases of ocular MG with diplopia associated with stable large ocular deviation for prolonged period that is refractory to appropriate medical therapy.

Keywords::

• ocular myasthenia gravis
• strabismus surgery
• treatment

Financial & competing interests disclosure

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pendin, or royalties.

No writing assistance was utilized in the production of this manuscript.

Key issues

• • Myasthenia gravis (MG) is the most common neuromuscular junction disorder.

• • Approximately 50% of patients with MG present purely ocular symptoms, a condition referred to as ocular MG (OMG).

• • The majority of patients with generalized MG (GMG) and roughly half of patients with purely ocular disease have detectable antibodies against skeletal muscle nicotinic acetylcholine receptors. Antibodies to other antigens (muscle-specific kinase, LDL receptor-related protein 4) and autoantibodies to acetylcholine receptors that are detectable only with a cell-based assay also have been reported to be related to pathogenesis of MG.

• • Acetylcholinesterase inhibitors are often the first modality of therapy for OMG. The response to this treatment in OMG patients is often incomplete and additional therapy may be required. It can be used in conjunction with immunosuppressive agents.

• • As an immune-mediated disorder, MG often responds to several immunosuppressive agents, such as corticosteroids or azathioprine. Corticosteroids have been considered a mainstay of treatment for OMG. Azathioprine also can be used effectively as an initial therapy for MG and several observational studies have showed the beneficial effects of azathioprine alone or in combination with prednisolone in patients with MG.

• • In patients with ptosis, simple ‘ptosis crutches’ can be helpful.

• • In patients with ptosis refractory to appropriate medical therapy or in whom ptosis is the only finding, eyelid surgery may be required. However, patients with myasthenic ptosis should be warned and counseled preoperatively about the possible need for further eyelid surgery to address either recurrent ptosis or symptomatic lagophthalmos.

• • For diplopia with a relatively stable angle of ocular deviation, prisms can be used.

• • Strabismus surgery also can lead to satisfactory results in selected cases of OMG with diplopia associated with stable large ocular deviation for prolonged period that is refractory to appropriate medical therapy. Care should be taken for the selection of surgical candidates among myasthenic patients and the patient should be counseled prior to surgery regarding the possibility of recurrence or adverse outcomes.