Measuring retinal blood flow in patients previously infected with COVID-19

Retinal Neurovascular Coupling in Patients Previously Infected With COVID-19

Observational Medical University of Vienna · NCT05650905

This study is testing how COVID-19 might affect blood flow and nerve function in the eyes of people who have had the virus, including those with long COVID, compared to healthy individuals.

Quick facts

Study typeObservational
Enrollment90 (estimated)
Ages18 Years and up
SexAll
SponsorMedical University of Vienna Academic / other
Locations1 site (Vienna, State of Vienna)
Trial IDNCT05650905 on ClinicalTrials.gov

What this trial studies

This observational study aims to assess retinal neurovascular coupling and blood flow parameters in individuals who have previously been infected with COVID-19, including those experiencing long COVID-19 symptoms, compared to healthy control subjects. The study utilizes non-invasive techniques such as Dynamic Vessel Analyzer (DVA), Fourier domain optical coherence tomography (FDOCT), and Laser Speckle Flowgraphy (LSFG) to visualize and measure the retinal response to flicker light stimulation. By examining these parameters, researchers hope to uncover potential residual effects of COVID-19 on retinal health and neurovascular function. The findings could provide insights into the neurological and vascular complications associated with COVID-19.

Who should consider this trial

Good fit: Ideal candidates include adults over 18 years old with a history of COVID-19 infection or long COVID-19 symptoms, as well as healthy individuals without prior COVID-19 infection.

Not a fit: Patients who are smokers or have significant ophthalmic abnormalities or other serious health conditions may not benefit from this study.

Why it matters

Potential benefit: If successful, this study could enhance understanding of the long-term effects of COVID-19 on retinal health and inform future treatment strategies.

How similar studies have performed: While there is emerging evidence regarding the neurological effects of COVID-19, this specific approach to studying retinal neurovascular coupling in this context is relatively novel.

Eligibility criteria

Show full inclusion / exclusion criteria
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

Where this trial is running

Vienna, State of Vienna

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions COVID-19Post-COVID-19 Syndrome
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.