Delayed diagnosis of optic nerve glioma: a preventable cause of visual loss.

Optic nerve glioma is a rare but important cause of visual impairment during childhood. The presenting symptoms and signs usually are visual, but are commonly misinterpreted. We report 18 children with visual loss secondary to optic nerve glioma. Thirteen of these patients presented with failing vision; only 3 had a correct initial diagnosis. The errors in diagnosis resulted in many years of treatment delay with consequent further visual impairment or no improvement in vision and a possible reduced efficacy of treatment. This delay may explain some of the controversy surrounding the role of radiotherapy in the management of these tumors. The diagnosis of optic nerve glioma must be considered in any child who presents with failing vision, optic atrophy, and/or nystagmus, in whom there is no demonstrable intraocular cause.