Author: Sandra Banderas García (Spain)
Co-authors: Miguel Ángel Zapata Victori, Fernando Trejo Velasco, Xavier Garrell Salat, David Aragón Roca, Brahim Azarfane, José García Arumí
To observe possible retinal capillary changes associated to COVID-19 infection and relate them to disease severity. It is well known that global pandemic SARS-CoV-2 causes a prothrombotic state and binds to ACE2 receptors.
A case-control study was designed and performed at Vall d’Hebron University Hospital (VHUH) in Barcelona, Spain
Participants between 18 and 55 years old with PCR-confirmed SARS-CoV-2 infection during the previous 3 months were randomly selected as cases (n=69) and stratified into groups (mild disease, moderate disease and severe disease). Last group included patients who developed acute respiratory distress syndrome with IL-6 values above 40 pg/mL. Control group was composed of 27 healthy subjects. All patients underwent a structured questionnaire, a retinography, a macula-centered OCT and a fovea-centered OCT-A. Statistical analyses were performed to detect vascular density differences in the superficial plexus of the retina.
There were no differences in statistical analyses regarding age, gender, smoking habit, comorbidities or drug intake (ACEI or ARB). Groups of moderate and severe disease had a statistically higher proportion of patients with Latin American origin (p=0.001) No macroscopic abnormalities were observed in retinographies, OCT macular images or in the vascular architecture, but a tendency to a bigger foveal avascular zone area was noted. Vessel densities had a normal distribution in means for central superior and nasal areas. In an ANOVA analysis, after Bonferroni correction for multiple measurements, statistically significant higher central VDs in controls and mild disease groups were noted (control group vs group 2, p=0.009; control group vs group 3, p=0.026; group 1 vs group 2, p=0.006; group 1 vs group 3, p=0.017).
The main finding of the study is the decrease of vessel density in central retina related to severity of COVID-19 disease but absence of macroscopic retinal lesions. There may be several explanations for this fact, for example, indirect consequence of the infection such subnormal oxygenation levels and requirement of supplemental oxygen. For another side, SARS-CoV-2 has been demonstrated to target endothelial cells. This fact could be responsible for capillary closure and micro-thrombotic events, which we eventually could detect as decreased vessel density in the retina and other organs. As angiography OCT is an easy non-invasive study, vessel density in central retina could be a future biomarker for microvascular abnormalities after the infection of SARS-CoV-2.