Assessing retinal risk with COVID-19 treatment

Interest in chloroquine and hydroxychloroquine for treating COVID-19 might raise concern among ophthalmologists regarding a risk of retinal toxicity. Even though these drugs are being used at relatively high doses as a potential treatment for COVID-19, the likelihood for causing retinal damage is exceedingly low, said Michael F Marmor, MD. In his conclusion, Dr Marmor states: “Ophthalmologists will be most effective in this time of crisis by reassuring physicians and the public where retinopathy is not a serious concern with respect to chloroquine or hydroxychloroquine usage for coronavirus”. Dr Marmor is Professor of Ophthalmology, Stanford University School of Medicine, Palo Alto, California, USA, and lead author of the American Academy of Ophthalmology (AAO) recommendations on screening for chloroquine and hydroxychloroquine retinopathy  Ophthalmology. 2016; 123(6):1386-1394. https://www.aaojournal.org/article/S0161-6420(16)00201-3/abstract He addressed whether their use for COVID-19 raises ophthalmological concern in an editorial published March 25, 2020 online in the American Journal of Ophthalmology. Citing the AAO recommendations, Dr Marmor observed that retinopathy is rarely seen before 10 years among patients who are treated with a daily hydroxychloroquine dose of <5mg/kg real weight (estimated equivalent for chloroquine = 2.3mg/kg). Although the doses being evaluated to treat COVID-19 are four- to five-fold higher than these levels, the duration of the antiviral treatment is very short term. Studies of patients receiving extreme doses of hydroxychloroquine for up to eight weeks reported no cases of visual loss. Findings from a study using OCT to follow patients treated with high-dose hydroxychloroquine for up to 25 months provides evidence that treatment with extreme doses of hydroxychloroquine or chloroquine might accelerate retinal toxicity, but with a probable time course of many months rather than days, Dr Marmor said. Taking into account the known relationships between dose, duration of administration and retinopathy risk, Dr Marmor states that treatment with hydroxychloroquine or chloroquine for <2 weeks will pose negligible ophthalmological risk even if the dose exceeds the AAO recommended maximum level by up to six-fold. Considering the scenario where treatment might continue for a few months, he suggests the risk of retinopathy remains low when using a daily dose that is <3- to four-fold higher than the equivalent of hydroxychloroquine 5mg/kg real weight. Addressing the issue of ophthalmological screening, Dr Marmor proposes that given the existing challenging circumstances of the pandemic, it would be counterproductive to suggest a need for eye examinations, which would be of low yield. Looking ahead, he states that the need for these assessments will have to be evaluated relative to the risk of retinopathy that their particular doses and durations of use may pose.

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