A case of left blepharoptosis in a patient with type 2 diabetes mellitus and myasthenia gravis

Background: The most common cause of blepharoptosis in individuals with diabetes mellitus is oculomotor paralysis due to diabetic mononeuropathy. Case Report: A 56-year-old male presented to an ophthalmologist with left blepharoptosis. Diabetic preproliferative retinopathy was diagnosed and the patient was referred to National Hospital Organization Kyushu Medical Center for further evaluation. On admission, right blepharoptosis was also noted, and his fasting plasma glucose and HbA _1c were 168 mg/dℓ and 9.2%, respectively. Proteinuria was detected and the Achilles tendon reflex was absent. He reported a 6-day history of diplopia and right blepharoptosis. On ophthalmic examination, the pupillary reaction to light was normal and ocular movement was smooth in all directions but restricted in range. The blepharoptosis improved after administration of edrophonium chloride. A test for serum anti-acetylcholine receptor antibody was positive and computed tomography of the chest showed thymoma. Later, he had a rapid onset of myasthenic crisis and underwent emergent thymectomy. Conclusions: Myasthenia gravis as well as cerebral aneurysm or brain tumor should be considered in the differential diagnosis of blepharoptosis.