Inherited optic neuropathies (IONs) are neurodegenerative disorders affecting the optic nerve and the nervous system. Dominant and recessive IONs are known. Many of the dominant IONs are caused by mutations of OPA1. Autosomal-recessive IONs are rare. OPA10 is an autosomal-recessive ION due to mutations in RTN4IP1. Patients with RTN4IP1 mutations show extraocular manifestations. We report brothers with optic neuropathy who had novel mutations in the RTN4IP1 gene. This is the first report of Japanese patients with OPA10. They showed extraocular manifestations resembling mitochondrial encephalopathy.