Retinal and choroidal microvasculature in early and three months post COVID-19: A case-control study

Abstract

To compare the retinal vascular density (VD), choroidal vascularity index (CVI), and choroidal thickness (CHT) between patients infected with COVID-19 and healthy subjects using non-invasive optical coherence tomography angiography (OCTA) and enhanced depth imaging OCT (EDI-OCT) technique. This case-control study was carried out on patients with COVID-19 and healthy controls. Patients' data were acquired immediately after active infection and three months later. The diagnosis was based on clinical symptoms and a positive PCR test. VDs in superficial and deep capillary plexuses (SCP and DCP) and CHT and CVI were measured and compared between groups. A total of 160 eyes from 80 patients (55 female, mean age 51 +/- 13 years) and 80 controls (55 female, mean age 49 +/- 12 years) were enrolled. In acute phase infection, the mean foveal avascular zone (FAZ) area was 0.28 +/- 0.06 mm(2) and 0.22 +/- 0.05 mm(2) in patient and control groups, respectively (P < 0.001). CVI was 61.06 +/- 2.59 <mu>m and 72.28 +/- 3.84 mu m in patients and control groups, respectively (P < 0.001). After three months, the mean FAZ area was 0.28 +/- 0.06 mm(2) and 0.23 +/- 0.05 mm(2) in the patient and control groups, respectively (P < 0.001). CVI was 60.93 +/- 2.11 mu m and 72.46 +/- 3.80 mu m in patients and control groups, respectively (P < 0.001). Subfoveal CHT was not significantly different between groups (P = 0.69). SCP and DCP VDs were significantly less in the patients' group (P < 0.001). In the patients' group, the VDs in the DCP of the whole images and parafoveal DCP (P < 0.001) were reduced significantly after three months in comparison to the acute phase, while the FAZ area, subfoveal CHT, and CVI were not significantly different.COVID-19 infection may be associated with acute and long-term changes of VDs in the retinal and choroidal vasculature without significant effect on the subfoveal CHT.