We thank Wiwanitkit1 for the comment on our article titled “Chloroquine (CQ) and Hydroxychloroquine (HQ) Retinal Toxicity Consideration in the Treatment of the Coronavirus Disease 2019 (COVID-19).”2 We agree with Wiwanitkit and have written clearly in our article that CQ and HQ are not proven useful for treatment of COVID-19. In addition, we did not recommend using CQ and HQ for treatment of patients with COVID-19.
Since there was no proven standard treatment of COVID-19 at the time of publication of our article but these two medications got emergency authorization for the treatment of COVID-19 by US Food and Drug Administration (FDA) in late March 2020, and were listed in guidelines of the treatment in many countries, we therefore stated that if these medications were to be used, history-taking for ocular disease should be conducted to avoid the prescription if appropriate. This key message of ocular history-taking is also what Wiwanitkit points out in the comment. However, the results from recently published randomized controlled trials suggested the lack of efficacy in using CQ and HQ for treating patients with COVID-19.3–5 Therefore, based on these new evidence, the US FDA has already revoked the emergency authorization of both medications for COVID-19 in June 2020.6
We also thank Martinez Navarro et al for their opinions related to our article in another letter to the editor titled “A Word of Caution in the Use of Hydroxychloroquine in the Elderly COVID-19 Population”.7 They also support the key message in our article on ocular history-taking in patients with COVID-19 before the prescription of CQ and HQ, particularly in elderly patients. They presented data from their own cohort of patients with COVID-19 who had chronic kidney disease combined with data from few more studies on other diseases to suggest that 3% to 5% of the patients might have preexisting ocular condition precluded the treatment with these medications.
Although there is still no evidence to date on retinal toxicity from the treatment with the high dose, short duration, of CQ and HCQ, there seems to be a consensus from physicians in various fields, not only in ophthalmology, on avoiding these 2 medications in elderly patients who have preexisting ocular disease.
1. Wiwanitkit V. Chloroquine, Hydroxychloroquine, Retinal Toxicity and COVID-19. Asia-Pacific J Ophthalmol (Phila).
2. Ruamviboonsuk P, Lai TYY, Chang A, Lai CC, Mieler WF, Lam DSC. Chloroquine and Hydroxychloroquine Retinal Toxicity Consideration in the Treatment of COVID-19. Asia-Pacific J Ophthalmol (Phila)
3. Tang W, Cao Z, Han M, et al. Hydroxychloroquine in patients with mainly mild to moderate coronavirus disease 2019: open label, randomised controlled trial. BMJ [Internet]
4. Huang M, Tang T, Pang P, et al. Treating COVID-19 with chloroquine. J Mol Cell Biol
5. Boulware D, Pullen M, Bangdiwala A, et al. A randomized trial of hydroxychloroquine as postexposure prophylaxia for covid-19. N Engl J Med
2020; doi: 10.1056/NEJMoa2016638.
6. Hinton DM. Letter revoking EUA for chloroquine phosphate and hydroxychloroquine sulfate, 6/15/2020 [Internet]. 2020 [cited 2020 Jun 16]. Available from: https://www.fda.gov/media/138945/download
7. Shukla AM, Martinez W, Ly L, Segal MS. A word of caution in the use of hydroxychloroquine in the elderly COVID-19 population. Asia-Pacific J Ophthalmol (Phila)