Ruamviboonsuk P, Lai TYY, Chang A, Lai CC, Mieler WF, Lam DSC; for Asia-Pacific Vitreo-Retina Society. Chloroquine and Hydroxychloroquine Retinal Toxicity Consideration in the Treatment of COVID-19. Asia Pac J Ophthalmol (Phila). 2020 Mar-Apr;9(2):85-87. doi: 10.1097/APO.0000000000000289. PMID: 32349115; PMCID: PMC7227199.

Ruamviboonsuk P, Lai TYY, Chang A, Lai CC, Mieler WF, Lam DSC; for Asia-Pacific Vitreo-Retina Society. Chloroquine and Hydroxychloroquine Retinal Toxicity Consideration in the Treatment of COVID-19. Asia Pac J Ophthalmol (Phila). 2020 Mar-Apr;9(2):85-87. doi: 10.1097/APO.0000000000000289. PMID: 32349115; PMCID: PMC7227199.

Abstract:

The proposed doses of chloroquine (CQ) and hydroxychloroquine (HCQ) for treatment of COVID-19 (1000 mg/day for 10 days, CQ; 800 mg first day then 400 mg/day for 5 days, HCQ) in many guidelines worldwide, are considerably higher than the maximum recommended daily safe doses of both agents (≤2.3 mg/kg/day, CQ; ≤5.0 mg/kg/day, HCQ) for development of retinal toxicity. Irreversible retinal damage can occur if the exposure to the safe doses is >5 years. It is not known whether exposure to high doses over a short period of time can also cause the damage. We recommend that before prescribing CQ or HCQ, history of ocular disease should be obtained to avoid the prescription if appropriate. If either agent is to be used, routine baseline ocular examination is not absolutely necessary. Patients who do not have ocular disease should also be informed about the potential risk of retinal toxicity. Both agents, however, have not yet been proven to be beneficial to COVID-19.

With the occurrence of pandemic of the coronavirus disease 2019 (COVID-19) announced by the World Health Organization in early March 2020 and the number of cases still on the rise in all continents in late March, many therapeutic options have been proposed for this novel and potentially fatal disease. Apart from antiviral agents, chloroquine (CQ) and hydroxychloroquine (HCQ) have been examined for their roles in treatment of COVID-19.1 This may be because both CQ and HCQ have been postulated to reduce viral replication in other coronavirus infections.2,3 According to a recent systematic review, there are almost 20 ongoing randomized controlled clinical trials on both medications for treatment of COVID-19 and all of them are in China. The details including dosing regimens of CQ and HCQ in these trials have been summarized in the review.4 Although there has not yet been a completed clinical trial and the world is waiting eagerly for the results of these trials and other trials on other treatment options, many authorities have chosen to adopt CQ and HCQ in the guidelines for treatment of COVID-19 based on in vitro studies,2,3 nonrandomized trial,5 and anecdotal evidence.6–11 As the therapeutic doses of CQ and HCQ recommended in the trials and guidelines are relatively high compared with the maximum daily safe dose that is related to CQ and HCQ retinal toxicity, this issue of retinal toxicity should be taken into consideration when employing these 2 medications for treatment of COVID-19 worldwide.

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