Retinal Neurovascular Coupling in Patients Previously Infected With COVID-19

Inclusion Criteria: Inclusion criteria for healthy subjects * Men and women aged over 18 years * Non-smokers * Normal findings in the medical history unless the investigator considers an abnormality to be clinically irrelevant * No previous history of COVID-19 infection * Negative testing for SARS-CoV-2 seroprevalence using nucleocapsid antibody tests * Negative PCR test for SARS-CoV-2 * Normal ophthalmic findings, ametropy \< 6 Dpt. Inclusion criteria for subjects with history of COVID-19 infection * Men and women aged over 18 years * Non-smokers * History of COVID-19 infection (confirmed by a positive PCR test for SARS-CoV2 in the medical history) within the last 6 months * Positive testing for SARS-CoV-2 seroprevalence using spike protein IgG antibody tests * Negative PCR test for SARS-CoV-2 Inclusion criteria for subjects with long COVID-19 * Men and women aged over 18 years * Non-smokers * History of COVID-19 infection (confirmed by a positive PCR test for SARS-CoV2 in the medical history) * Positive testing for SARS-CoV-2 seroprevalence * Negative PCR test for SARS-CoV-2 * Long Covid according to the latest WHO-Guidelines Exclusion Criteria: Any of the following will exclude a healthy control subject from the study: * Symptoms of a clinically relevant illness in the 3 weeks before the first study day * Presence or history of a severe medical condition as judged by the clinical investigator * Participation in a clinical trial in the 3 weeks preceding the study * Blood donation during the previous three weeks * History or family history of epilepsy * Presence of any abnormalities preventing reliable measurements in the study eye as judged by the investigator * Best corrected visual acuity \< 0.8 Snellen * Pregnancy, planned pregnancy or lactatin * History of epilepsia Any of the following will exclude a subject with history of COVID-19 infection from the study: * Blood donation during the previous three weeks * History or family history of epilepsy * Presence of any abnormalities preventing reliable measurements in the study eye as judged by the investigator * Best corrected visual acuity \< 0.8 Snellen * Ametropy \>6 Dpt * Pregnancy, planned pregnancy or lactating * History of epilepsia Any of the following will exclude a subject with long COVID-19 from the study: * Blood donation during the previous three weeks * History or family history of epilepsy * Presence of any abnormalities preventing reliable measurements in the study eye as judged by the investigator * Best corrected visual acuity \< 0.8 Snellen * Ametropy \>6 Dpt * Pregnancy, planned pregnancy or lactating * History of epilepsia * Diabetes mellitus