The clinical presentation, diagnosis, response to therapy, and visual outcome of 18 children with optic nerve glioma are reported from the Division of Neurology, Department of Pediatrics, University of British Columbia, Vancouver, Canada. Failing vision was the presenting symptom in 13 patients and 15 had an incorrect initial diagnosis which resulted in many years of treatment delay with consequent further visual impairment and reduced efficacy of treatment. In patients presenting with visual impairment, the time from presentation to diagnosis was 28 months whereas in five with increased intracranial pressure, the diagnosis was made within three months. Incorrect initial diagnoses included idiopathic nystagmus (3), congenital optic nerve atrophy (3), squint, diencephalic tumor, multiple sclerosis, and hysteria. Following radiotherapy, an improvement in vision was observed only in those children who presented with increased intracranial pressure and who were diagnosed early. Multiple cafe-au-lait spots were observed in five children. 
COMMENT. In young children presenting with nystagmus, squint, optic atrophy, or visual impairment, the possibility of optic nerve glioma should be considered. The diagnosis is especially likely if signs of neurofibromatosis are associated. Early diagnosis may prevent visual loss and may influence the efficacy of radiotherapy.