Treatment for diplopia in patients with myasthenia gravis

The purpose of this study was to describe the treatment experiences and outcomes of patients with myasthenia gravis (MG) whose initial presenting symptom was diplopia A retrospective review was performed on a group of patients with MG whose initial presenting symptom was diplopia. The mean age of onset was 45.5 +/- 16.9 years, and the mean follow-up period was 45.4 +/- 39.7 months. Exotropia with vertical heterotropia was the most common type of deviation. The mean horizontal deviation was 20.1 +/- 17.9 prism diopters, and the mean vertical deviation was 14.8 +/- 11.1 prism diopters. Limitation of eye movement was found in 20 patients (71.4 %) during the follow-up period. After conventional treatment for MG, six patients (21.4 %) showed a good response with resolution of diplopia. Four patients (14.3 %) showed a partial response to treatment. Eighteen patients (64.3 %) showed minimal or no response; among them, ten (35.7 %) had an angle of deviation of 15 prism diopters or more. Six patients underwent strabismus surgery. Four were symptom free, and satisfactorily aligned after surgical treatment. One patient had intermittent diplopia despite the small amount of deviation, and one patient experienced recurrence of exotropia with diplopia during the 10-year follow-up. In multivariable analysis, the only factor associated with the need for strabismus surgery was the initial angle of deviation (p = 0.016). Patients with MG who have a larger angle of deviation at presentation tend to require strabismus surgery after stabilization of the disease. Strabismus surgery is one treatment option for patients with MG who have a large angle of deviation and respond poorly to conventional treatment.