Patients are sometimes referred to Retina of Coastal Carolina because they are on Plaquenil. This is a derivative of chloroquine that can cause toxicity to the macula.
Chloroquine was first used to treat malaria but has since been found to be effective in treatment of rheumatoid arthritis and other inflammatory diseases. Retinal toxicity is common at high doses. A closely related drug, hydrochloroquine was found to be considerably less toxic but just as effective. Consequently, chloroquine is not used any more for inflammatory diseases in the United States but is still used outside of USA. It is still used for prophylaxis and treatment of malaria. The drug accumulates in the pigmented tissues such as the retinal pigment epithelium (RPE) and can cause a Bull’s eye retinopathy so named because of its target-like appearance.
The frequency of retinopathy is less than 5% when dosages of less than 6.5 mg/kg per day of hydroxychloroquine are used. That is usually less than 400 mg/day. Our practice is consulted for baseline testing, usually within the first 6 months of starting drug. The recommended follow up is 6 months to 1 year. A recent survey of retinologists and rheumatologists found that the majority were doing 6 months follow up. Between follow up appointments we recommend weekly Amsler grid testing at home.
Risk factors for retinopathy include daily dose greater than 6.5 mg/kg (ideal body weight), greater than 10 years of use, liver problems, kidney problems and age over 60.
When hydroxychloroquine toxicity is detected stopping the medication often halts the progression. The rheumatologist needs to be consulted before stopping the medication.
Fortunately toxicity is rare and nowadays detected early.