Characterization of patients with ocular myasthenia gravis — A case series

•A relatively high prevalence of ocular myasthenia gravis•Ocular myasthenia gravis affected more male than females.•Anti-AChR Ab detected fewer ocular MG patients than generalized MG patients.•Female with ocular MG had more thymus hyperplasia and other autoimmune disorders than male.

Ocular myasthenia gravis (OMG) is sometimes difficult to diagnose and is probably both under-diagnosed and misdiagnosed. We studied the epidemiological parameters, relevant serology, electromyographic (EMG) findings, and the relationship between OMG and thymoma, thymus hyperplasia and other autoimmune disorders compared to generalized MG (GMG) in a case control study of 133 patients with MG (32 patients with OMG and 101 patients with GMG). The proportion of OMG among all MG patients was relatively high (24.1%). It affected more males than females and its onset was at an older age. Although anti-AChR Ab was detected in fewer OMG patients compared to GMG patients, the rate of positive serology in OMG patients was higher than previously reported. Male OMG patients had a higher positive serology rate than female OMG patients. OMG patients tended to have less supportive EMG evidence of neuromuscular disorder. Female OMG patients had higher rates of thymus hyperplasia and higher rates of other autoimmune disorders than males.Diagnosing MG in patients with solitary ocular manifestation may be difficult due to lower rates of paraclinic supportive tests. Awareness of the characteristics of OMG is important in order to avoid delayed or misdiagnosis of MG and to prevent avoidable iatrogenic complications.