The investigators will recruit patients with PCS, fully COVID-19 recovered participants and COVID-19 infection naïve participants. After comprehensive clarification and given written informed consent, measurements will take place in the Klinikum rechts der Isar. To evaluate the retinal microvasculature dynamic retinal vessel analysis (DVA) and optical coherence tomography (OCT) are used. Patient reported outcomes (PROM) of PCS typical symptoms will be collected using standardized questionnaires. To ensure data quality the investigators will use standard operating procedures (SOP) for both technical measurements and data collection. For DVA measurements all examiners will be trained by a single experienced supervisor and must reach high image accuracy and quality in at least 10 volunteers. Examiners are only involved in data acquisition.
The goal of this observational, prospective study is to in depth analyze the retinal microvasculature in patients with Post-COVID-19 Syndrome (PCS). The main questions it aims to answer is:~Do patients with PCS show a prolonged endothelial dysfunction when compared with fully COVID-19 recovered participants? Does symptom severity in PCS patients correlate with the extend of endothelial dysfunction? Do these changes correlate with improvement in symptoms in the prospective observation?