Juvenile Ocular Myasthenia Gravis: Presentation and Outcome of a Large Cohort.

Background: Isolated ocular myasthenia gravis (MG) is sparingly common in children relative to adults, ranging from 71% to 93% of all children with MG.

Purpose: We aimed to characterize the ocular manifestations and outcomes in children with isolated ocular MG.

Methods: Medical records of consecutive 62 subjects less than 15 years of age with ocular MG, were retrospectively reviewed. Demographic data, presenting ocular features, types and variabilities of duction limitation, MG confirmatory tests, types of and responses to treatment, and generalized MG conversion were reviewed.

Results: Mean age at onset and follow-up time were 49 months (range, one to 173 months) and 95 months (range, six to 226 months), respectively. Female-to-male ratio was 1.5:1. Initially, ptosis was found in 60 subjects (96.8%), while duction limitation was observed in 28 subjects (45.2%). Total ophthalmoparesis was the most common type of duction limitation. Variability of duction limitation was found in 68% of subjects during the follow-up. Pyridostigmine alone was the most common medication used (48.4%); ptosis was more responsive to therapy than duction limitation. Conversion to generalized MG occurred in 19.4% of subjects, with a mean interval to conversion of nine months after symptom onset. Most conversions (91.7%) occurred in the first two years.

Conclusions: Ptosis was more responsive to treatment than duction limitation. Thus other treatment modalities, as well as strabismic amblyopia screening, should be considered in children with prolonged duction limitation that is refractory to medication. In contrast with adults, a much lower proportion of children converted to generalized MG. This may explain the higher prevalence of isolated ocular MG among the juvenile population.