New research, released by a team based in Turkey, Qatar, and the United Kingdom, has indicated that a specialised eye exam can be used to identify long COVID.

Published in the British Journal of Ophthalmology, the research found that corneal confocal microscopy (CCM) – a non-invasive eye test that conducts real-time imaging of corneal nerve fibres – can also potentially be used to confirm suspected cases of long COVID by identifying specific nerve damage.

CCM is also used to identify other conditions, such as diabetic neuropathy, Parkinson’s disease, multiple sclerosis, and dementia.

THE LARGER CONTEXT

Penned by researchers from Turkey’s Necmettin Erbakan University, Weill Cornell Medicine-Qatar (WCM-Q), and the UK’s University of Manchester, the study stated that CCM “identifies corneal small nerve fibre loss and increased DCs [dendritic cells] in patients with long COVID, especially those with neurological symptoms.”

As a result, “CCM could be used to objectively identify patients with long COVID.”

The paper added: “Long COVID is characterised by a range of potentially debilitating symptoms which develop in at least 10% of people who have recovered from acute SARS-CoV-2 infection.”

Symptoms of long COVID include headache, tingling and/or numbness, neuropathic pain, a loss or change in the senses of taste and smell, and so called “brain fog”.

WHY IT MATTERS

According to a statement by WCM-Q, “nerve damage observed in the corneas using CCM can be reliably used as an indicator of nerve damage in other parts of the body.

“CCM’s value as a diagnostic tool is increased by a number of important factors: the test takes only a few minutes, is completely non-invasive, causes almost no discomfort for patients, utilises existing and widely available ophthalmic equipment, and can be done in the clinic.”

ON THE RECORD

“The predominance of neurologic symptoms in people with long COVID prompted us to investigate whether CCM could be used to objectively identify nerve damage in patients with the disease,” said Rayaz Malik, professor of medicine and assistant dean for clinical investigations at WCM-Q. “We are the first group in the world to report a very strong association between nerve damage observed using CCM and long COVID. 

“Although the majority of people had mild COVID, patients with more severe disease had evidence of greater corneal nerve damage, suggesting that the severity of nerve damage may be related to the severity of disease at presentation.

“We believe CCM has the potential to serve as an extremely valuable tool to be used by physicians to help diagnose and assess the evolution of long COVID and to determine the severity in individual cases. The identification of underlying nerve damage also allows us to think about this condition as a neurodegenerative disease, which may be amenable to treatment.”