Amiodarone is a medication prescribed to manage heart rhythm disorders. While effective, it has potential side effects affecting various organ systems. The eyes are particularly susceptible, leading to a spectrum of ocular manifestations.
Common Ocular Manifestations
The most common eye side effect of amiodarone is corneal deposits, often called cornea verticillata or amiodarone-induced keratopathy. These deposits appear as yellowish-brown, whorl-like patterns on the cornea’s surface.
Corneal deposits are very common, affecting nearly all patients (around 70-100%) who take amiodarone, especially with long-term use and higher dosages. Despite their high prevalence, these deposits are generally considered benign. Patients usually do not experience any visual complaints, though some may report mild symptoms such as glare, halos around lights, or slightly blurred vision, particularly in bright light or at night.
The appearance of these corneal whorls typically occurs within months of starting the medication. While they rarely cause significant visual impairment, it is worth noting that other medications like chloroquine, hydroxychloroquine, and indomethacin can also cause similar corneal deposits. The deposits are usually reversible, gradually disappearing within months after the discontinuation of amiodarone, though their resolution may take some time.
Less Common but Serious Eye Effects
Amiodarone-induced optic neuropathy (AION) is a less common but severe ocular side effect. This condition affects the optic nerve, which transmits visual information from the eye to the brain. While rare, it can lead to significant vision loss.
Symptoms of AION can include a sudden or gradual decrease in visual acuity, affecting one or both eyes. Patients may also experience changes in color perception (dyschromatopsia) and visual field defects. The onset of visual loss can be insidious, with a mean duration of amiodarone use before symptoms appear being about 9 months.
AION is characterized by protracted optic disc swelling, which can persist for several months after discontinuing the medication, unlike other types of optic neuropathy where swelling resolves more quickly. Although it can resemble non-arteritic anterior ischemic optic neuropathy (NAION), AION often presents with a milder degree of vision loss and is more commonly bilateral, affecting both eyes simultaneously or in close proximity. Other extremely rare ocular side effects reported with amiodarone include anterior subcapsular lens opacities (cataract-like changes) and maculopathy, though these typically do not cause significant visual disturbance.
Monitoring and Management
Regular eye examinations are recommended for patients taking amiodarone to monitor for potential ocular side effects. A baseline ophthalmologic exam should be performed before starting the medication, and periodic follow-up exams are advised throughout the course of treatment. Annual ophthalmologic exams are suggested for patients on long-term amiodarone therapy to detect corneal deposits or optic neuropathy.
These examinations typically involve assessing visual acuity, performing a slit-lamp examination to check for corneal deposits, and conducting a dilated fundus examination to evaluate the optic nerve. Patients should be encouraged to visit an eye care professional at least once a year, even if they are not experiencing symptoms.
Immediate medical attention is necessary if a patient experiences new or worsening visual symptoms, such as sudden vision changes, severe glare, or any discomfort. If amiodarone-induced optic neuropathy is confirmed, discontinuation or dose reduction of amiodarone may be considered to prevent further vision loss, always under the supervision of a cardiologist. Corneal deposits, however, usually do not require discontinuation of the drug unless the symptoms are severe and significantly impact vision.