The impact of acute COVID-19 on the retinal microvasculature assessed with multimodal imaging

To quantify retinal microvascular findings in the acute phase of COVID-19 using multimodal imaging and compare them with healthy, age-matched controls.

Hospitalized patients in the acute phase of COVID-19 without known systemic comorbidities (n = 75) and healthy controls (n = 101) aged 18-65 were enrolled in this prospective cross-sectional study. The retinal microcirculation and microvasculature impairments were assessed using fundus photography, swept-source optical coherence tomography, and swept-source optical coherence tomography angiography in the COVID-19 unit and compared with healthy, age-matched controls.

Retinal findings were predominately observed in patients with severe disease (P = 0.006). Patients with severe disease were shown to have increased both mean vein diameter (Coef. = 19.28, 95% CI: 7.34-31.23, P = 0.002) and mean artery diameter (Coef. = 11.07, 95% CI: 0.84-21.67, P = 0.044). Neither blood vessel diameters were correlated with any confounding variables (age, sex, treatment with oxygen, LDH, or ferritin). Patients with severe COVID-19 were shown to have significantly increased retinal nerve fiber layer thickness in the superior and inferior quadrants both in the inner (S: P = 0.046; I: P = 0.016) and outer (S: P = 0.026; I: P = 0.014) ring and significantly increased GCL thickness in the outer temporal quadrant (P = 0.038). There were no statistically significant differences in vessel density or the foveal avascular zone area between the groups.

The severity of COVID-19 was significantly correlated with the presence of retinal microangiopathy, which could become a biomarker of angiopathy in patients with COVID-19.