Optic Perineuritis Distinguishing Arteritic Ischaemic from Amiodarone-Associated Optic Neuropathy.

Giant cell arteritis (GCA) is a common medium to large vessel vasculitis of the elderly that can lead to permanent vision loss. Neuroimaging in GCA may reveal optic nerve sheath enhancement, which is a cardinal finding of optic perineuritis (OPN). The clinical manifestations of GCA can mimic that of other ocular disorders including amiodarone-associated optic neuropathy (AAON). We report a case of biopsy-proven GCA in a patient initially suspected to have AAON. This patient presented with bilateral optic disc oedema in conjunction with subacute predominately monocular vision loss and enhancement of the corresponding optic nerve sheath on neuroimaging. Clinicians should recognise that clinical and neuroimaging findings of GCA can mimic a variety of ocular and orbital pathologies including idiopathic OPN and AAON.