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Hydroxychloroquine for Coronavirus: Is Possible Retina Damage Worth the Treatment?

Even though it’s a mouthful of a word, hydroxychloroquine has recently entered the public vernacular in a big way. It’s made a splash in the news as a potentially effective drug in combating Covid-19, and has been touted by President Trump as a viable tool in the struggle against the disease. The drug has many clinical uses, including malaria prophylaxis and treatment of rheumatoid arthritis. Furthermore, it can be mass produced in huge quantities at relatively low cost. 

Not all are sold on the effectiveness of hydroxychloroquine for Covid-19, however. Doctors have pointed to the potential side effects and contraindications of the drug, some of which may be serious. 

Matt interviewed Dr. Fong from his quarantine room while Matt had coronavirus.

Hydroxychloroquine and Eye Damage

Hydroxychloroquine for Coronavirus: Is Possible Retina Damage Worth the Treatment?
All pills and no play makes Jack a blind boy.

Indeed, one of the main side effects can be damage to the eyes. How serious is it? Malaysian ophthalmologist Dr. Ken Fong explained his experience with the drug. “Hydroxychloroquine is actually a treatment for rheumatology conditions, so rheumatologists use it most,” he said. “Ophthalmologists only see these patients because hydroxychloroquine can cause blindness. This drug can actually deposit in the retina and cause permanent loss of vision, so we need to monitor the dose very carefully.”

Notably, many hospitals in Sweden have already stopped using the drug for Covid-19 treatment. A story from the country is circulating about a man who is struggling with vision problems (Swedish language) after chloroquine treatment. According to the article, the man was given high enough doses of the drug to be toxic and he suffered loss of peripheral vision as well as blurred central vision. 

Chloroquine is a drug similar to hydroxychloroquine. Of the two, chloroquine presents a greater danger. 

“Hydroxychloroquine has a much lower dose than chloroquine itself,” said Dr. Fong. “The safest to use is hydroxychloroquine and the recommended dose is 400 mg/day or something like that.” The recommended dosage varies by body weight — the American Association of Ophthalmology (AAO) has recommendations on dosage

Despite being safer than its medical cousin, hydroxychloroquine can still cause problems. “The dose that is recommended by these doctors for Covid-19 is quite high and it may cause problems with your vision,” notes Dr. Fong. Worth noting is this: a case from 2019 included a patient who had only been taking the drug for two months before she developed vision problems. While cases like these may be rare, we’ll likely hear much more about short-term use, especially with Novartis donating 130 million pills to fight Covid-19.

Hydroxychloroquine: For Severe Cases Only?

Hydroxychloroquine for Coronavirus: Is Possible Retina Damage Worth the Treatment?
Unfortunately, there are no guinea apples for Covid-19 treatments.

The drug seems to have its place in the fight against Covid-19 — but it may not be the go-to weapon of choice. 

“In Malaysia, it’s being reserved for the seriously sick patients because there is a shortage of it and we are not aware of its side effects,” said Dr. Fong. 

“My infectious disease colleagues who are treating Covid-19 patients say that this is still considered an experimental treatment and is only reserved for severely ill patients,” he continued. “Those that need to go to ICU, with kidney failure, cardiac failure, with lung failure, these patients are going to do badly no matter what you give them I think.”

Dr. Reena Sethi agreed with Dr. Fong that hydroxychloroquine should be reserved for patients with severe cases of Covid-19. “I’m not sure whether everybody should be taking chloroquine because it does have a lot of toxicity,” she said. “It’s hepatotoxic, and it can cause problems to the optic nerve as well.” 

Matt interviewed Dr. Sethi from his coronavirus quarantine lair.

There certainly are patients who may benefit from taking the drug: those who are in dire straits and would be willing to attempt any and all treatments. 

“If I was really ill I’d definitely try anything,” explained Dr. Fong. “But you have to understand that on top of hydroxychloroquine the doctors are going to give patients antivirals as well. We don’t know the interaction between hydroxychloroquine and antivirals. Malaysia has been chosen by the WHO to trial a new antiviral. I think new trials are going to start this week. I think these antivirals will probably be more useful than hydroxychloroquine.”

Hydroxychloroquine as a Prophylactic?

Hydroxychloroquine for Coronavirus: Is Possible Retina Damage Worth the Treatment?
Maybe anything is better than getting the virus.

The drug may show some promise as a prophylactic treatment — especially due to the often asymptomatic nature of Covid-19. Those infected with the SARS-CoV-2 virus may be asymptomatic for up to two weeks during the incubation period, during which time they can shed the virus. 

“For health workers who have been exposed to the virus or who have been working closely with Covid patients — it’s a good prophylactic medication for that,” said Dr. Sethi.  

While there’s no indication the drug actually prevents patients from being infected, it does appear to lessen symptoms. As Dr. William Trattler noted, “We don’t know for sure that it’ll prevent the virus but it will shorten the infection and mitigate the severity of infection in your body.” He recommends avoiding hydroxychloroquine as a prophylactic for the uninfected — rather, it should be used in confirmed cases to prevent mild cases from becoming severe. 

Dissenting Voices

Hydroxychloroquine for Coronavirus: Is Possible Retina Damage Worth the Treatment?
One doctor’s no-no is another’s a-OK.

Clearly, some medical professionals advocate the use of hydroxychloroquine as a Covid-19 treatment. Doctors make battlefield decisions, using the information available to inform their opinions. Sometimes, this simply means using what seems to work while balancing risks and benefits. 

“People are dying,” said Dr. Trattler. “If it (hydroxychloroquine) can stop people going to the ICU then it’s well worth the risk.” He recently authored an article in which he opined in favor of the drug. 

He also disagreed with the risk threshold of hydroxychloroquine, and noted that the dosage a patient takes over a lifetime matters more than the short-term dosage. In general, he said, there needs to be a long-term use of the drug over many years for the drug to be dangerous. 

Specifically, he noted a cumulative dosage of 1000 grams or 5000 pills is necessary to risk elevated levels of toxicity. In the meantime, a typical dose over the course of a Covid-19 treatment is 2000-6000 milligrams — less than 0.6% the cumulatively dangerous level. 

Zinc can boost the effects of hydroxychloroquine as well, according to Dr. Trattler. Hydroxychloroquine is effective at making zinc more bioavailable, and zinc has been shown to disrupt the replication process of the virus. 

Doctors’ Orders

Hydroxychloroquine for Coronavirus: Is Possible Retina Damage Worth the Treatment?
If you see an image like this in real life, something has gone terribly wrong.

One thing is clear: Patients should not self-medicate with hydroxychloroquine. There are too many unknowns for this drug to be used without a doctor’s supervision. Patients who are going to take the drug need to have a pre-medication screening first. For example, getting your eyes checked for pre-existing conditions is an advisable course of action. Before you visit your doctor, you can check out this site to gauge your potential retinal toxicity risk. 

More food for thought: In addition to eye damage, the drug can lead to arrhythmia — especially when combined with the antibiotic azithromycin, which is a popular combination. Dr. Trattler strongly suggests any patient who is going to receive this treatment get an EKG and have their heart checked thoroughly first. 

In the fight against the coronavirus, any weapon can be valuable. Whether hydroxychloroquine becomes the go-to choice for doctors or just another arrow in the quiver remains to be seen. In the meantime, health professionals around the world are working harder than ever before to find a treatment. We can at least take comfort in that. 

Dr. Ken Fong

About the Contributing Doctors

Consultant Vitreoretinal Surgeon Dr. Kenneth Fong, MA MB BChir (Cambridge), FRCOphth
(UK), FRANZCO (Aust), CCT (UK), AM (Mal), is recognized as an ophthalmologist in the UK,
Australia and Malaysia. He graduated with a medical degree from the University of Cambridge
in 1998 and trained to be an eye surgeon in London. Dr. Fong then spent two more years
training in the UK and at the Royal Perth Hospital in Australia to subspecialize in retina. After
18 years of working in the UK and Australia, he returned to Malaysia in 2009 to serve at
associate professor and consultant ophthalmologist and retinal surgeon at the University of
Malaya in Kuala Lumpur. He is currently the managing director of OasisEye Specialists in Kuala Lumpur. Dr. Fong is the president of the Malaysian Society of Ophthalmology and serves as a council member for the Asia Pacific Vitreo-retinal Society. [Email:]

Dr. Reena Sethi

Dr. Reena Sethi is the Medical Director of Arunodaya Deseret Eye Hospital, India. Together with her husband, Dr. Arun Sethi, they have over 30 years of experience in clinical and surgical ophthalmic practice. They are consultants to leading hospitals in New Delhi, including Indraprastha Apollo Hospital, Escorts Heart Institute and Research Centre, Diplomatic Missions: including the American Embassy, British High Commission, and the Canadian High Commission. They are also members of leading professional ophthalmic societies such as the American Society of Cataract and Refractive Surgery (ASCRS), American Academy of Ophthalmology (AAO), and All India Ophthalmological Society (AIOS). Through the Arunodaya Charitable Trust (ACT) and the Arunodaya Deseret Eye Hospital (ADEH), Drs. Arun and Reena Sethi have found success in giving back with their work to treat curable blindness among the poorer populations in New Delhi, India.[Email:]

Dr. William Trattler

Dr. William B. Trattler, M.D. is a refractive, corneal and cataract eye surgeon at the Center For Excellence In Eye Care in Miami, Florida, USA. He performs a wide variety of cataract and refractive surgeries, including PRK; all laser LASIK; no injection, suture-less cataract surgery; as well as laser cataract surgery. He has been an investigator for next generation technologies (like the Tetraflex accommodating intraocular lens) and procedures like corneal collagen crosslinking (CXL). His involvement in the FDA-approval study for CXL led to its approval in 2016. In addition to his private practice, Dr. Trattler is on the Volunteer Faculty at the Florida International University Wertheim College of Medicine, as well as the University of Miami’s Bascom Palmer Eye Institute. He is board certified by the American Board of Ophthalmology and has been an author of several articles and abstracts. In 2016, Dr. Trattler received the Catalyst Award in Advancing Diversity in Leadership from the Ophthalmic World Leaders (OWL), an association of interdisciplinary ophthalmic professionals dedicated to driving innovation and patient care by advancing diversity in leadership. [Email:]

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