Eye problems after COVID-19 can now be explained

Mild COVID-19 can cause severe and long-lasting eye problems, according to a study from Linköping University, Sweden. The study also explains why it has been difficult for sufferers to get help: the abnormal eye behaviour cannot be detected by standard methods. The researchers have developed a diagnostic model to detect COVID-related eye problems.

‘It’s very important that the problem is recognised and that we show that it can be measured by objective testing,’ says Prof Neil Lagali, professor of experimental ophthalmology at Linköping University, who led the study published in Nature Communications. ‘Patients don’t have access to that [testing] today. We’ve studied people in Sweden, but believe that many people around the world are experiencing these problems.’

The study originated with people seeking care for eye problems following a mild COVID-19 infection. They were experiencing a lot of discomfort, sensitivity to light and in many cases severe eye pain, difficulty reading and focusing their gaze.

The researchers examined 100 people with eye problems following COVID-19 who had not been hospitalised. They had suffered from eye problems for between three months and three years, and one in three were on full or part-time sick leave. The researchers compared the affected group with a control group of 32 people, who had also had mild COVID-19 but without eye problems.

‘We found that the problems experienced by those affected were not detectable by standard tests. We had to perform specialised examinations to detect deviations. The puzzle pieces then fell into place, and we found explanations for the symptoms,’ says Neil Lagali.

In their study, the researchers found long-term inflammation and deterioration of several eye functions controlled by the nerves in the brain.

One of the advanced tests involved proteomics, where a variety of proteins in the tear fluid are analysed. In those with eye problems, the researchers found an abnormal pattern of proteins regulating nerves and immune cells, so-called T cells. The findings were consistent with advanced eye microscopy that they used to measure the T cells and nerves in the eye. Strikingly, the same protein pattern has been found in blood and tissue in cases of severe and fatal COVID in other studies.

‘Our findings suggest that these people have suffered a severe reaction to COVID-19 manifested in the eyes, with long-term inflammation and an impact on the nerves that control multiple eye functions,’ says Dr Petros Moustardas, senior research associate at Linköping University and lead author of the study.