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Infectious Diseases

22 May 2020

Covid-19: Amid caution over use of hydroxychloroquine, experts warn of possible irreversible blindness

Despite evidence that hydroxychloroquine is not effective in Covid-19 patients, it is still being touted as a miracle drug. But what about its retinal effects?

Hydroxychloroquine, a drug used to treat lupus and rheumatological disorder, has received a massive amount of publicity this year. The reason? Its role in the Covid-19 pandemic.

The drug made headlines after being proposed as a preventative measure (prophylaxis) against Covid-19, as reported in the New York Times.

While hydroxychloroquine has generally fewer side-effects than its cousin chloroquine, which was also researched as a possible Covid-19 treatment, it was generally declared as ineffective against the novel coronavirus, based on several studies.

But, besides the fact that the hydroxychloroquine hype may cause those who really need the medicine for lupus not being able to find it, the drug can also have irreversible side effects, as discussed in the journal Nature.

Hydroxychloroquine’s effect on your eyes

Toxic retinopathy is a condition where vision is impaired as a result of optic nerves being damaged by a toxin, such as found in some medications. 

Several previous studies have acknowledged that long-term use of hydroxychloroquine may lead to this condition. But with the heightened interest in hydroxychloroquine during the Covid-19 pandemic, the European Reference Network for Rare Eye Disease became especially concerned about the drug’s role in toxic retinopathy, especially in patients who already have inherited retinal dystrophy (a condition where one or both eyes lose vision over time).

Retinopathy caused by hydroxychloroquine is also sometimes referred to as bulls-eye maculopathy, as the condition affecting the retina surrounding the macula resembles a target or “bulls-eye” ring.

At first, the central vision isn’t affected, but a ring of disrupted vision around the centre of the eye is experienced. As it progresses to the centre of the eye, the entire vision can be affected and vision loss is permanent in most cases.

Those who are chronically on hydroxychloroquine for anti-rheumatic purposes or the treatment of lupus are generally more at risk, and should undergo comprehensive eye exams more often.

But according to Nature, not only patients on chronic hydroxychloroquine are in danger, but also those who take it as self-medication without supervision by a medical professional.

If a person suffers from any comorbidity such as renal impairment or obesity, they are also more likely to be at risk of vision loss.

Other problems with hydroxychloroquine

Besides the retinal effect of hydroxychloroquine, there are many other systemic side-effects that can be experienced when this drug is taken for the wrong reasons and in the wrong quantities.

One of these is cardiac complications that can potentially be fatal. The Food and Drug Administration (FDA) in the United States has also issued a statement that hydroxychloroquine should not be taken without supervision by your medical advisor, as this may lead to heart rhythm irregularities.

Earlier in April 2020, Health24 published an article debating the potential of chloroquine and hydroxychloroquine as a Covid-19 treatment. 

Professor Wolfgang Preiser from the Division of Medical Virology at the University of Stellenbosch recently stated that the evidence of chloroquine and hydroxychloroquine being beneficial in Covid-19 patients is minimal, and generally flawed, and that panic buying could prevent those who depend on the drug for existing conditions from getting it.

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