Abstract
BackgroundNon-arteritic ischaemic optic neuropathy (NAION) is a rare but harmful complication of prone positioning. Prone mechanical ventilation is a therapeutic strategy which has been used extensively during the COVID-19 pandemic to treat acutely hypoxemic patients with COVID-19 related acute respiratory distress syndrome (ARDS). Though a small number of cases of unilateral NAION have been reported in patients testing positive for the SARS-CoV-2 virus, we describe what is to our knowledge, the first reported case of bilateral NAION occurring in a patient proned extensively for the treatment of COVID-19 related ARDS. We consider the potential aetiological factors leading to NAION after prone mechanical ventilation in patients with COVID-19 and suggest strategies to protect against its development.Case presentation: We report a case of severe, irreversible, visual impairment secondary to bilateral anterior ION in a fifty-five-year-old male who underwent eight episodes of prone mechanical ventilation to treat COVID-19 related ARDS. Once weaned from his sedation he reported bilateral painless vision loss, and bedside ophthalmological assessment identified a reduced visual acuity of 3/30 unaided in the left eye and counting fingers in the right. Dilated indirect ophthalmoscopy revealed inferotemporal optic disc oedema with splinter haemorrhages in the right eye and mild disc oedema, temporal pallor, and nerve fibre layer haemorrhages inferiorly in the left eye. Humphrey visual field 24 − 2 testing confirmed a severely constricted visual field with macular sparing on the right and depressed inferonasal vision with preserved peripheral vision on the left eye. OCT disc imaging shortly after diagnosis revealed bilateral disc swelling and flame haemorrhages in the right eye.ConclusionsNAION is a devastating, but preventable complication of prone positioning, which may pose significant risk of vision loss in patients with COVID-19 related ARDS.
Highlights
Non-arteritic ischaemic optic neuropathy (NAION) is a rare but harmful complication of prone positioning
Anterior NAION occurs due to infarction of the posterior ciliary arteries supplying the optic disc, and posterior NAION occurs due to infarction of the pial capillary plexus which supplies the retrolaminar optic nerve[1]
NAION presents as sudden, painless irreversible vision loss, which typically occurs upon waking[2].Early ophthalmic assessment is central to the diagnosis of NAION in patients with COVID-19 related acute respiratory distress syndrome (ARDS), as their ability to report visual loss is limited by the use of tracheal intubation and deep sedation in the context of critical illness[3]
Summary
NAION is a devastating, but preventable complication of prone positioning, which may pose significant risk of vision loss in patients with COVID-19 related ARDS.
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