Amiodarone and optic neuropathy

To investigate the clinical, perimetric, contrast sensitivity and visual evoked potentials findings in patients on longterm treatment with amiodarone.

We enrolled 14 patients (age range 47-78 years, mean age 62.7 years) on chronic amiodarone therapy (mean cumulative dose of 519 g), and 14 age-matched control subjects. Participants were submitted to ophthalmological examination, kinetic visual field testing (Goldmann), standard achromatic automated perimetry (central 30-2, Humphrey), computerized isoluminant chromatic contrast sensitivity (CCS) and pattern visual evoked potentials evaluation (VEP). Data from baseline, 6-month and 1-year follow-up examinations were analysed. The main outcome measures were: initial and final corrected visual acuity; corneal, optic disc and fundus abnormalities; mean deviation (MD) and pattern standard deviation (PSD) central 30-2 perimetry parameters; visual field loss on kinetic perimetry; indices of CCS (tritan, protan and deutan axes), and pattern VEP latency (L-VEP) and VEP amplitude (a-VEP).

We found a statistically significant difference between the patients and controls' baseline L-VEP and a-VEP measurements (p < 0.001). We found no significant correlation between prolonged L-VEP and duration of amiodarone use (r = 0.07). After a 1-year follow-up, we evidenced an average increment in L-VEP of 1.96 ms and a-VEP measurements showed a decline of 0.69 micro V. In cumulative dose-specific analyses, mean differences between baseline and 12-month L-VEP measurements were more evident in those taking higher than 200 g cumulative amiodarone doses (p = 0.03). We found abnormal tritan CCS results in 19 eyes (68%). Of these, four eyes belonged to patients with no ocular disease (diabetes, cataracts). No significant differences were observed between the baseline and 12-month clinical eye examinations, central 30-2 perimetry and CCS results.

We found a significant prolongation in pattern L-VEP and a significant reduction in pattern a-VEP in patients on longterm treatment with amiodarone compared to control subjects. Nevertheless, current data are insufficient to recommend appropriate methods of visual screening.