New insights into amiodarone induced retinal and optic nerve toxicity: functional and structural changes

BACKGROUND: Amiodarone is widely used for heart arrhytmia. Previous studies have suggested the possibility of optic neuropathy with the chronic use of this drug. OBJECTIVES: To identify structural or functional changes in the retina and optic nerve in patients on chronic amiodarone therapy without visual complaints. METHODS: This observational study included 15 eyes of 15 patients with cardiac arrythmia on chronic amiodarone treatment and 15 healthy matched subjects as a control group. All subjects underwent electrophysiological tests [pattern visual evoked potential (PVEP), pattern electroretinogram (PERG), multifocal electroretinogram (mfERG), and optical coherence tomography (OCT) and angiography (OCTA)]. RESULTS: There were no statistically significant differences between the two groups regarding the PVEP, PERG, and the mfERG parameters. Macular and optic nerve head OCT and OCTA have not shown statistically significant differences except for the morphological parameters of the optic disc (p = 0.008 for the horizontal and p = 0.013 for vertical cup/disc ratio and p = 0.045 for rim area). CONCLUSION: Patients on chronic amiodarone therapy have not shown evident structural or functional changes in the retinal or optic nerve as demonstrated by electrophysiological tests, OCT, and OCTA results compared to controls.