A Hydroxychloroquine headache

SES, 23 May 2020

Staying true to evidence-based eyecare

 

Real science and medical testing will always trump a gut-reaction, feel-good approach to the diagnosis and treatment of patients. Dr Logan Robinson looks at the recent chaos behind unproven ‘cures’ and the very real effects of Hydroxychloroquine on eyesight.

Donald Trump has been on the news over the last few weeks promoting the use of a medication called Hydroxychloroquine (HCQ) for the prevention and treatment of COVID-19. The widespread condemnation of this touting was with good reason – there is no evidence HCQ provides benefit to these patients.

In fact an international study of nearly 100,000 patients has provided evidence that HCQ is probably harmful in COVID-19 treatment. With reports the treatment was doing more harm than good the World Health Organisation has halted clinical trials also.

With the ‘information age’ giving way to a ‘disinformation’ one many people would prefer to take medical advice from someone who makes the loudest noise however. For the good of everyone, it’s preferable to listen to those who actually know what they are talking about.

Over time HCQ can build up in the retina, the light sensitive layer at the back of the eye, leading to loss of central vision.

We monitor Hydroxychloroquine use at Southern Eye Specialists. That’s because the anti-malarial medication is used most commonly to treat autoimmune conditions such as Systemic Lupus Erythematosus and Rheumatoid Arthritis here in New Zealand.

How is this of any relevance to the eye?

Over time HCQ can build up in the retina, the light sensitive layer at the back of the eye, leading to loss of central vision. Ophthalmologists play a vital role in monitoring for these serious side effects. 

That’s why all patients started on HCQ should have a baseline eye examination to determine their risk of developing toxicity to the retina.

Based on the results of this examination a personalised monitoring schedule will be recommended by the ophthalmologist. Risk factors for retinal toxicity include treatment with HCQ for more than 5 years and higher daily doses. These groups of patients require more frequent monitoring. 

The key to preventing visual loss from HCQ toxicity is detecting the earliest signs of damage to the retina, before they have caused any symptoms. Then, in conjunction with the doctor who prescribed the Hydroxychloroquine, it may be the case of stopping the medication to prevent further damage and loss of vision.

The earliest way to pick up toxicity is with 3 key tests: 

  • OCT macula: A high-definition, high magnification scan of the central retina to detect subtle toxicity damage to the photoreceptor cells (rods and cones)
  • Fundus autofluoresence: A special photograph of the retina that can highlight retinal cells which are showing the first signs of toxicity
  • Central visual field test: This test can detect small patches of central visual loss before they are noticeable to patients

We use the Heidelberg Spectralis for OCT and autofluorescence images, widely considered the best in the business for OCT scanning. We have also recently invested in the gold standard in visual field testing, the Zeiss Humphrey Automated Visual Field Analyzer 3.

This new technology reduces the time taken to perform visual field tests, improving both the experience for patients and quality of results for the ophthalmologist.

This is not a cursory or ad-hoc approach. HCQ-related vision loss is a risk that must be diligently managed and one reason why we’ve invested heavily in the highest-specification diagnostic equipment.

SES must therefore always be able to monitor HCQ toxicity with clarity – and recommend treatment with confidence. While we may not have the media spotlight of certain ex-reality show hosts our expertise in evidence-based treatment is far more helpful to the ongoing health of New Zealanders.

Normal fundus autofluoresence image.

Autofluorescence image of patient with HCQ toxicity.

The u-shaped lighter patch in the centre is abnormal.

OCT macula scan showing HCQ damage to photoreceptors (arrows).