Orbital hydrocephalus: a proven cause for optic atrophy.

A 4-year-old boy with bilateral optic sheath enlargement and progressive optic atrophy and blindness is presented. Computed tomography demonstrated hydrocephalus and enlargement of the optic nerve sheath complex. The child died during an attempted repair of hypoplastic atrioventricular valves. Autopsy demonstrated a patulous perioptic subarachnoid space and optic atrophy. This condition has been described in the literature but has not had radiologic-pathologic correlation. With the availability of magnetic resonance imaging, this diagnosis may be made prospectively, thus, it is important for the radiologist to be aware of this entity because optic atrophy and blindness may be prevented by early diagnosis and surgery.