Walsh & Hoyt: Amiodarone

Amiodarone is a benzofuran derivative that is primarily used to treat atrial or ventricular tachyarrhythmias that are unresponsive to other antiarrhythmic agents. Amiodarone's therapeutic mechanism of action is related to its ability to prolong the duration of action potentials and the refractory period in cardiac-conducting tissues. The most common ocular side effect is the formation of verticillate, pigmented, corneal epithelial deposits that eventually occur in most patients (70-100%) treated with the drug. The amount of corneal epithelial deposits observed in a given patient, as well as the incidence of these deposits in a group of patients, is related to the dose of the drug and the duration of treatment. With discontinuation of the drug, the deposits resolve over several months as amiodarone has a long half-life of up to 100 days. Other ocular side effects from amiodarone include anterior subcapsular lens opacities, multiple chalazia, and keratitis sicca. Fortunately, these ocular side effects rarely cause significant visual impairment and do not constitute a reason for discontinuing the drug.