Optic Neuropathy Due to Compression by an Ectatic Internal Carotid Artery Within the Orbital Apex

Neurovascular compression is a rare but potentially treatable cause of optic neuropathy. Although incidental contact of the cisternal optic nerve and internal carotid artery (ICA) is common, compressive optic neuropathy occurring within the orbital apex has not been comprehensively described. We report a case of intra-orbital and intracanalicular optic nerve compression due to an ectatic ICA in a patient with congenital absence of the contralateral ICA. This report describes the complementary roles of advanced neuroimaging and neuro-ophthalmologic examination in rendering the diagnosis.