DRUGS WITH OCULAR SIDE EFFECTS OF RECENT CLINICAL IMPORTANCE
AMIODARONE (CORDARONE®)
Primarily
used to treat various cardiac arrhythmias.
Clinical
Concerns
• Corneal deposits (100%) may interfere with
vision, especially with night driving
• Color vision defects
• This photosensitizing drug may cause
discoloration of the eyelids and conjunctiva (typically yellow– brown or
gray–blue)
• Cataracts – anterior subcapsular, seldom
interfere with vision
• Baseline ophthalmic examination
• Follow-up examination every 6 months
(controver-sial)
• Instruct patients to see ophthalmologist promptly
in case of any visual disturbance
Amiodarone-induced
optic neuropathy is an impor-tant recent finding. As in many cases, it may be
impossible to distinguish NAION from amio-darone optic neuropathy; consultation
with a neuro-ophthalmologist may be necessary. Many patients taking amiodarone
may already have compromised optic nerves due to vascular disease; amiodarone
deposition in the axons further impedes neural func-tion, causing vision loss.
The
cause of amiodarone neuropathy is unknown but may be because of selective
accumulation of intra-cytoplasmic lamellar deposits or by-product inclu-sions
(primary lipidosis) in optic nerve axons. This may mechanically or
biochemically decrease axoplas-mic flow. Resultant optic nerve head edema may
persist as long as transport is inhibited, i.e. as long as several months
following discontinuation of amiodarone, which has a half-life of up to 100
days. Edema caused by NAION resolves much more rapidly. To date, there are no
reported cases of amio-darone neuropathy causing no light perception (NLP).
Finally, the degree of amiodarone neuropathy may not be equal in each eye for a
few months but usually will become equal if therapy is continued. Stopping the
drug, in consultation with the cardiologist, at the first signs of optic nerve
involvement must be considered unless the ophthalmologist is very confident of
the diagnosis of NAION.
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