The most important risk factors are dosage and duration of use. ![]() The latest screening guidelines were published in 2016 by the American Academy of Ophthalmology ( Table 1). These fundus photos, of the right and left eyes respectively, reveal parafoveal ring-shaped “bull’s eye” RPE defects. 5 Thus preventing and detecting early effects of retinal toxicity prior to irreversible complications is key. 4 However, research now shows toxicity continues even after cessation of the drug. ![]() 3 The toxicity would double by 10 years, resulting in a 20% prevalence after 20 years. The risk of retinal toxicity was initially believed to be less than 1% after long-term (or a cumulative dosage of 1,000mg). Plaquenil toxicity is typically asymptomatic in early stages, but over time can lead to severe vision loss and retinal damage. Binding of the drug to melanin in the RPE contributes to, or prolongs, its toxic effects. 1 This leads to disruption and damage to the photoreceptors and outer nuclear and plexiform layer, sparing the foveal center and resulting in the “bull’s eye” appearance in the late stage of the disease. The mechanism of this toxicity is not clearly understood, though it is believed that the drug molecule binds to melanin in the retinal pigment epithelium (RPE). Plaquenil is less toxic than chloroquine however, long-term use of either drug can result in macular toxicity, leading to devastating irreversible vision loss. Plaquenil (hydroxychloroquine sulfate, Sanofi-Aventis) and the less-used chloroquine are antimalarial drugs with anti-inflammatory properties that are used for the management of a spectrum of inflammatory conditions.
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