Dynamics of retinal perfusion parameters in patients with post-COVID syndrome

BACKGROUND: A major current health issue is the rehabilitation of patients who previously had a coronavirus infection (COVID-19), as well as the treatment of patients with post-COVID syndrome. For a long time after COVID-19, patients may have complaints, including vision-related ones. One of the theories is that this may be due to long-term persistent microcirculatory retinal changes. AIM: To assess the long-term dynamics of retinal microcirculation changes in patients with post-COVID syndrome and to evaluate the relationship of these parameters with visual functions. MATERIALS AND METHODS: The main group consisting of 41 patients (82 eyes) was divided into groups depending on the severity of COVID-19: mild, moderate and severe. The control group included 13 people (26 eyes) who did not have COVID-19 to the time of the examination. All patients underwent an ophthalmological examination, including low-contrast visual acuity testing and optical coherence tomography-angiography. Vessel density (VD) was examined within the superficial capillary plexus (SCP), deep capillary plexus (DCP), and radial peripapillary capillaries (RPC). The following structural indicators were also measured: the retinal thickness, the retinal nerve fiber layer thickness and the ganglion cell complex. All patients were examined twice: 6 weeks after COVID-19 and in 27 weeks (6 months after the first visit). RESULTS: Patients who went through moderately severe and severe COVID-19 showed a significant decrease in low-contrast visual acuity in comparison to the control group at Visit 1 (p .001 in both cases), which totally recovered to the Visit 2. In the same group of patients, there was a significant decrease in VD SCP (p .001) and VD DCP (p .001) in comparison to the control group, and these parameters significantly decreased at visit 2 (p .001 in both cases). In the group of patients with moderate COVID-19, there was also a decrease in VD SCP and VD DCP in comparison to the control group (p .001 in both cases), while the indicators remained stable during 6 months of follow-up (p = .082). There were no significant changes in VD RPC and main morphometric parameters during 6 months of follow-up. CONCLUSIONS: In patients with COVID-19 from moderate severity to severe, there is a significant decrease in contrast sensitivity, which is temporary and fully recovers after 6 months. In patients with severe COVID-19, there was a negative dynamic of retinal perfusion during 6 months, both in deep and superficial capillary plexuses. Patients with post-COVID syndrome, or those who have had COVID-19 and present with visual complaints, need a deep ophthalmological examination including optical coherence tomography-angiography, with a possible involvement of related specialists.