[Optic nerve sheath meningiomas].

Optic nerve sheath meningiomas account for one-third of optic nerve tumors, 1-2 % of all meningiomas, and 2-3.5 % of all orbital tumors. Loss of vision is the main clinical sign. Diagnosis is easily made after the neuroradiological evaluation. Fractionated stereotactic radiotherapy (RSF) is now the gold standard treatment for controlling tumor volume and preserving visual acuity.