Published: June 2011

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Watch out for amiodarone's eye effects

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Prescriber Update 32(2): 16
June 2011

Amiodarone use is associated with the development of ocular adverse effects including optic neuropathy (which occurs rarely) and corneal deposits (which occur in most patients).

All patients experiencing new or worsening visual symptoms whilst taking amiodarone should be referred for ophthalmological assessment. Amiodarone should be stopped if optic neuropathy is confirmed due to the potential for progression to permanent visual loss.¹

Optic neuropathy can present with decreased visual acuity, decreased colour vision, an afferent pupillary defect and/or visual field loss. Drug induced optic neuropathies usually occur in both eyes, either simultaneously or in close proximity, and improves or resolves when the offending medicines are discontinued.²

The Centre for Adverse Reactions Monitoring (CARM) has received 51 reports of eye-related adverse reactions to amiodarone up to April 2011. These include 3 reports of optic neuropathy, 19 reports of corneal deposits and 12 reports of abnormal vision.

Reports to CARM highlight the variable presentation of amiodarone associated optic neuropathy. One case involved a 63-year-old woman who developed sudden onset of left sided visual loss two weeks after stopping amiodarone (which she had received for six weeks prior to successful cardioversion). A second case involved a 67-year-old man who first noticed visual changes four months after starting amiodarone. Initial examination found reduced visual acuity in the right eye. One year later this had progressed to complete visual loss in the right eye and substantial visual loss in the left eye.

Consistent with CARM reports, the published literature indicates that amiodarone associated optic neuropathy usually occurs within 12 months of starting amiodarone (median time to onset of 4 months).³ Visual loss can be acute or gradual, with approximately 65% of cases presenting with evidence of bilateral optic neuropathy.

Patients treated with amiodarone may also be predisposed to anterior ischaemic optic neuropathy due to their underlying cardiovascular risk factors. The differentiation of this cause of visual loss from a drug induced optic neuropathy can be difficult but both diseases can result in severe visual loss.

Amiodarone monitoring guidelines in New Zealand recommend that baseline eye examinations be performed in patients with pre-existing visual impairment.⁴ Follow-up eye examinations are recommended for all patients who develop visual symptoms while taking amiodarone.

Prescribers are reminded to enquire about visual symptoms during follow-up visits and to continue to report suspected serious and/or unexpected adverse reactions to amiodarone to CARM.

References

1. Sanofi-aventis New Zealand Limited (Dec 2010). Cordarone X data sheet. Available at www.medsafe.govt.nz/profs/Datasheet/c/CordaroneXtabinj.pdf
2. Li J et al (2009) Drug-Induced Ocular Disorders. Drug Safety 31 (2): 127-141.
3. Johnson L N et al (2004) The Clinical Spectrum of Amiodarone-Associated Optic Neuropathy. Journal of the National Medical Association 96(11): 1477-1491.
4. Mann S (2008) Amiodarone monitoring. BPJ 14: 50.