Should patients who need treatment with hydroxychloroquine (HCQ) for the treatment of COVID-19 worry about retinal toxicity?
This is a question I have been asked given that there is quite a bit of news coverage about the possible therapeutic benefit of hydroxychloroquine as a treatment for COVID- 19. The pandemic of coronavirus disease 2019 (COVID-19) caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) presents an unprecedented challenge to identify effective drugs for prevention and treatment No proven effective treatments for this virus exist.
HCQ is a safer form of chloroquine and is used much more commonly in the US than chloroquine. HCQ’s trade name is Plaquenil. HCQ is frequently used for the treatment of rheumatologic diseases such as rheumatoid arthritis and Lupus. Most patients using it for this purpose take 200-400mg per day over years. We know there is a risk of retinopathy from the drug when used for years. The risk is low but increases with time. In fact, the risk is somewhere around 1-7.5% after 5 years of usage but increases to about 20% after 20 years. The retinopathy is irreversible, so it is important that the drug is stopped as soon as toxicity is identified. Eye care specialists can make the diagnosis of toxicity by screening the patients with multimodalities including the following tests: color vision, visual field, optical coherence tomography, autofluorescence, and flicker or multifocal ERG. Patients with macular disease such as age-related macular degeneration, are advised not to use HCQ.
Luckily, the COVID-19 patients receive the drug for usually one week, so their risk of developing retinopathy is slim. When faced with respiratory distress from COVID-19, it seems that the benefit of using HCQ outweighs the drug’s risks. However, if you do take HCQ during this COVI- 19 outbreak, when you recover, I would suggest seeing your eye care specialist to insure the health of your eyes. I would also highly recommend going into a randomized, clinical, peer review trial, if offered, because that is the only way we can really determine if a treatment has value. There are many being conducted in the US now. Since the disease is so prevalent and the endpoint is weeks to months, we will have good clinical information within months if patients enroll in these studies.