Hydroxychloroquine Retinal Toxicity and Its Association with Dosage

To the Editor:

A recent clinical image of hydroxychloroquine (HCQ) retinal toxicity has been recently published¹. In this case, the patient who presented with symptoms was on long-term treatment with HCQ at more than twice the recommended dose related to her weight, and the tests were consistent with established retinopathy.

HCQ retinopathy has been extensively studied lately. Recent data show an increased risk for toxicity among patients receiving doses > 5 mg/kg/day (i.e., 300 mg/day in a woman of average weight). Otherwise, those taking < 4 mg/kg/day had a frequency of retinopathy < 10% even after more than 20 years of therapy². A recent study in the Lupus-Cruces cohort found no relevant retinal changes measured by optical coherence tomography over a 5-year follow-up and no cases of established toxicity³. The median dose of HCQ was 3.12 mg/kg/day, with 99% of patients having received < 5 mg/kg/day.

Therefore, clinicians managing patients with systemic lupus erythematosus (SLE) must be aware that HCQ retinal toxicity mostly depends on the daily dose. Treating patients with < 5 mg/kg/day would make those kinds of images a real rarity in the future, assuring long-term treatment as the cornerstone of SLE therapy⁴.