Absence of bilateral vision loss from amiodarone: a randomized trial.

Background: Amiodarone's role as a cause of toxic optic neuropathy is based on case reports. Annual frequency estimates of 0.36% to 2.0%, which have been made without reference to the dose or duration of treatment, are 12 to 200 times higher than those for idiopathic nonarteritic anterior ischemic neuropathy. The object of this study was to determine the incidence, dose, and time until onset of bilateral vision loss from amiodarone as a secondary end point in an investigation of amiodarone's role in preventing sudden death.

Methods: Randomized subjects received body weight-determined doses of closed-label amiodarone (n = 837) or placebo (n = 832) in a prospective double-masked manner. Closed-label amiodarone subjects were followed, unless death occurred, for a minimum of 27 months. Median follow-up in survivors was 45.5 months. The end point was removal from the study because of bilateral vision loss.

Results: No subject was removed from the study because of bilateral vision loss. Subjects receiving continuous amiodarone for 4 to >60 months at daily doses of >2.0 mg/kg (n = 696), >3.0 mg/kg (n = 559), or >4.0 mg/kg (n = 219) had maximum possible (95% confidence) annual incidences of bilateral toxic vision loss of 0.23%, 0.29%, or 0.74%, respectively. The maximum possible annual incidence rate of bilateral vision loss from amiodarone in all 837 subjects (median age 60 years) receiving a mean daily dose of 3.7 mg/kg (300 mg) was 0.13%.

Conclusions: At the doses commonly used clinically, bilateral vision loss from amiodarone toxic optic neuropathy occurs infrequently, if at all.