To describe a child with muscle-eye-brain disease as the first case report in Korea.

A 35-month-old girl presented with esotropia and nystagmus since birth. She was born with a birth weight of 3.45 Kg at the gestational age of 39 weeks. She had a history of developmental delay and developmental dislocation of the hip. Her elder sister also had generalized weakness and mental retardation. The patient's creatinine kinase and lactate dehydrogenase serum levels were high. Cycloplegic refraction showed a significant myopic astigmatism in both eyes. She showed nystagmus and 20 prism diopters of esotropia in the primary position with the alternative prism cover test. Slit lamp examination revealed a mild posterior subcapsular cataract and lower lid epiblepharon in both eyes. Funduscopic examination showed diffuse retinal degeneration with remnant hyaloids membranes in both eyes. Both optic nerves were dysplastic with abnormal vascular branching pattern. Flash visual evoked potential was normal and standard electroretinography showed decreased amplitude in both eyes. Brain magnetic resonance imaging (MRI) revealed diffuse T2 high signal lesions of the cerebral white matter, diffuse pachygyria of the cerebral cortices, pontine hypoplasia, and multiple small cerebellar cysts.

When a child with developmental delay has ophthalmologic problems including severe myopia, cataract, strabismus and retinal degeneration, the systemic condition should be examined. In this case, in addition to the ophthalmologic findings, blood test and brain MRI were helpful for the diagnosis of muscle-eye-brain disease.