Imaging of the pre-chiasmatic optic nerve.

Damage to the optic nerve (ON) is characterised by a reduction in visual acuity. Pre-chiasmatic lesions to the optic nerve may be of traumatic, congenital, tumoral (meningioma, glioma), inflammatory or vascular origins. In all cases, MRI is the choice means of exploration, carried out with axial and coronal sections with a thickness of 2.5-3mm and T1 and T2-weighted spin echo sequences. The coronal sections may be carried out with fat signal saturation for an elective study of the size of the retrobulbar portion of the ON.