Retrobulbar ocular blood flow and choroidal vascular changes in patients recovering from COVID-19 infection

Background: To evaluate the effects of COVID-19 infection on the ocular vascular structure including choroidal thickness and retrobulbar blood flow values in comparison with healthy subjects. Methods: Ninety eyes of 90 patients were included in this study. Participants were divided into Group 1 (n - 30) with mild COVID-19 infection, Group 2 (n = 31) with moderate disease, and Group 3 with age-and sex-matched healthy subjects (n = 29). Choroidal thickness was measured at the subfoveal area and at 500-mu m intervals nasal and temporal to the fovea up to a distance of 1500 mu m, using the enhanced depth imaging (EDI) technique of spectral coherence tomography (SD-OCT). The peak systolic velocity (PSV), end diastolic velocity (EDV), resistive index (RI), and pulsatility index (PI) values of the central retinal artery (CRA) and ophthalmic artery (OA) were evaluated with color Doppler ultrasonography (CDU). Results: The choroidal thickness was significantly thinner in Group 1 and Group 2 than in Group 3 at all mea-surement points (p<0.001). This difference was not present between Group 1 and Group 2 who had COVID-19 disease of different severity (p>0.05).Among the retrobulbar blood flow parameters, OA PSV value was signif-icantly lower in Group 1 and Group 2 compared to Group 3 (p = 0.025, p = 0.016, respectively). However, the CRA PSV and EDV and OA EDV values, and the CRA and OA PI and RI values were not statistically different between the groups (p> 0.05). Conclusion: COVID-19 infection may predispose patients to ocular vascular pathologies by affecting both choroidal and retrobulbar blood flow.