Question: Hydroxychloroquine is commonly used in the treatment of a variety of rheumatologic diseases including lupus, and rheumatoid arthritis as well as for the treatment of certain malignancies (e.g. non-small cell lung cancer). What is the time course for the development of retinal toxicity in relation to the use of this drug?
Answer: The listed article notes: “The risk of hydroxychloroquine mediated retinal toxicity is relatively low within the first 5-10 years of therapy when used at daily doses that do not exceed 5mg/kg, typically 200-400mg daily”. However when used at very high doses (e.g. 1000 mg per day), “hydroxychloroquine can initiate the development of retinal toxicity within 1-2 years”. (Leung LB et al. Rapid onset of retinal toxicity from high dose hydroxychloroquine given for cancer therapy. 2015 Am J Opthal 160(4):799-805)