Optic nerve sheath meningioma--report of three cases.

Meningiomas involving the optic nerve and the anterior visual pathways have intrigued neurosurgeons, neurologists and ophthalmologists for more than a century. They may present with the classical triad of progressive painless visual loss, optic atrophy and opto-ciliary bypass vessels. Optic nerve sheath meningiomas are most frequently diagnosed radiologically and lately, magnetic resonance imaging has greatly improved their visualisation. Surgical removal to preserve vision has met with dismal results. We present three patients with optic nerve sheath meningiomas which were diagnosed based on radiological findings. One had improvement in her visual acuity after external beam irradiation. Another had the tumour excised by a neurosurgeon. The last patient absconded follow-up and returned with no deterioration in her visual acuity after three years.