Chloroquine and Hydroxychloroquine

What is it?

Chloroquine prevents malaria
Hydroxychloroquine treats rheumatic illnesses
Most common ophthalmic side effect: damage to retinal pigment epithelium, causing irreversible vision loss
Retinal toxicity uncommon with chloroquine and even less common with hydroxychloroquine as long as proper dose limits observed
Ophthalmologic monitoring protects against severe toxicity

Blurred vision in both eyes
Pericentral scotomas on special visual fields
Fading of orange color of retina around fovea ("bull’s eye maculopathy"), appearing well after visual symptoms begin
Optical coherence tomography and multifocal electroretinography may reveal abnormalities before they are visible with ophthalmoscope and perhaps even before patient develops symptoms

Have patients treated with chloroquine undergo baseline ophthalmic examination and be monitored by ophthalmologist every 3-6 months after starting it
Have patients treated with hydroxychloroquine undergo baseline ophthalmic examination and be monitored yearly starting at 5 years of medication use
Keep chloroquine daily dose at <3 mg/kg/day and cumulative dose at <460 gm to reduce chances of retinopathy
Keep hydroxychloroquine daily dose at <5.0mg/kg/day and cumulative dose at <1000gm to reduce chances of retinopathy
Recognize that patients with renal failure are at unusually high risk of retinal toxicity
Stop medication at first suggestion of retinal toxicity

Chloroquine and hydroxychloroquine retinopathy rare if recommended dose limits followed
Once visual symptoms develop, they cannot be reversed, and may worsen even if medication stopped
Monitoring with visual fields, optical coherence tomography, and electroretinography allows earlier detection of toxicity and may prevent disabling vision loss