Evaluation of retinal and choroidal parameters as neurodegeneration biomarkers in patients with post-covid-19 syndrome.

Background: To investigate the neurodegenerative effects of post-COVID-19 syndrome.

Methods: This comparative, cross-sectional study included patients who had post-COVID-19 prolonged neurologic symptoms. The control group was selected from volunteer participants with similar age, sex, and spherical equivalent characteristics. After detailed ophthalmic examinations, spectral-domain optic coherence tomography (SD-OCT) analysis of the macula and peripapillary retinal nerve fiber layer (m-RNFL, p-RNFL respectively) were obtained. We also evaluated the choroidal parameters with the ImageJ software. Post-COVID-19 symptoms and disease severity of the patients were also questioned.

Results: Thirty-four eyes of 20 patients, and 39 eyes of 23 healthy individuals were included in the study. Thinning was found in the inner superior quadrant of mRNFL (p < 0.05). More prominent and common thinning of retinal layers was observed in the ganglion cell layer (GCL) and inner plexiform layer (IPL) segments in the patient group. There was no difference between the groups in the calculated choroidal parameters (p > 0.05). In the regression models created, lung involvement was the most prominent parameter associated with thinning of the OCT layers. The other factors were male sex, and the presence of loss of taste and smell also led to deterioration in some parameters.

Conclusions: We detected an overall thinning of the GCL and IPL layers with no significant change in CMT, pRNFL, and CVI in the post-COVID-19 period, indicating the direct or indirect effect of SARS-CoV-2 on these layers, rather than a long-term neurodegenerative effect.