ABSTRACT
Purpose@#We report a case of idiopathic chiasmal optic neuritis in a pediatric patient.Case summary: A 13-year-old boy with no history of systemic disease was referred to our ophthalmology clinic because of visual disturbance in both eyes of 5 days in duration. The best-corrected visual acuity was 0.08 in the right eye and finger counting at 30 cm in the left eye; mild blurring of the disc margins (both eyes) was evident on fundus examination, as were temporal hemianopsia in the right eye and diffuse field loss in the left eye. Brain magnetic resonance imaging revealed focal nodular enhancement in the optic chiasm. Blood and cerebral fluid analysis yielded no evidence of infection or autoimmune disease. Therefore, we diagnosed isolated idiopathic chiasmal optic neuritis and commenced a systemic steroid. After 5 days, the visual acuity began to improve, and the field defect was almost eliminated (except for a small central scotoma) at 1 month. He has remained stable to the time of writing (4 months after treatment) and his visual acuity has normalized. @*Conclusions@#Isolated idiopathic chiasmal optic neuritis developed in a pediatric patient and the visual function improved after steroid treatment. Although there was no evidence of systemic demyelinating disease, regular observation is scheduled given the possibility of late-onset disease.