Evaluation of the choroidal structural and vasculature changes following COVID-19 infection and vaccination using optical coherence tomography angiography

To investigate the impact of COVID-19 infection and various COVID-19 vaccines on choroidal structure, vasculature, and the foveal avascular zone (FAZ) using optical coherence tomography angiography (OCTA). This prospective study included 200 participants, divided equally into five groups: 40 healthy controls, 40 individuals one month after COVID-19 infection, and three groups vaccinated with AstraZeneca, Pfizer, or Sinovac. OCTA was performed to measure choroidal thickness (CT), choriocapillaris thickness (CCT), choroidal vessel density (CVD), choriocapillaris vessel density (CC-VD), and FAZ parameters. There were no significant differences among the five groups in central or mean CT (p = 0.246 and p = 0.053, respectively). However, significant differences were observed in both central and mean CCT (p < 0.001 and p = 0.006, respectively). Central and mean CVD also varied significantly among the groups (p = 0.004 and p = 0.035, respectively), with central CVD being significantly higher in the COVID-19 group than in the AstraZeneca and Pfizer groups (p = 0.034 and p = 0.03, respectively). Mean CC-VD differed significantly among all groups (p = 0.006), showing the highest values in the control group and the lowest in the COVID-19 group. No significant differences were found regarding FAZ area or perimeter (p = 0.174 and p = 0.334, respectively). However, FAZ circularity was significantly reduced in the COVID-19 group compared to the control and Pfizer groups (p = 0.008 and p = 0.004, respectively). COVID-19 infection and certain vaccine types may cause subtle but detectable changes in the choroidal microvasculature. These findings demonstrate the sensitivity of OCTA in identifying microvascular alterations in the posterior segment and enhance understanding of how different COVID-19 vaccines may influence ocular microcirculation.