Optic neuropathies caused by toxins and adverse drug reactions.

Toxic optic neuropathy refers to the ingestion of a toxin or an adverse drug reaction that results in vision loss from optic nerve damage. Patients may present with bilateral sudden loss of vision in the setting of an acute intoxication or an insidious asymmetric loss of vision from an adverse drug reaction. Toxins and drugs associated with a toxic optic neuropathy may directly harm the optic nerve; however, some drugs are associated with an ischemic optic neuropathy or optic neuritis, in which optic nerve damage is an indirect effect of the causative agent. The most important aspect of treatment is recognition and drug withdrawal. Patients need to be appropriately counseled, particularly in the setting of amiodarone-associated optic neuropathy.