Choroidal Microvascular Alterations in COVID-19 Patients

Objective To evaluate alterations in the choroidal angioarchitecture of COVID-19 patients using optical Coherence Tomography (OCT) based surrogate markers. Methods This prospective case-control study recruited 56 COVID-19 patients (111 eyes) and 61 healthy individuals (120 eyes). Choroidal thickness (CT) and Choroidal vascularity index (CVI) were derived from OCT images using a purpose-built automated software for choroidal image segmentation. A linear mixed model with age and gender as covariates was employed to compare CVI and CT between groups. Results COVID-19 patients had significantly higher subfoveal (81.3um vs 86.8um, p = .02), temporal (78.8um vs 84.3um, p = .005), nasal (87.5um vs 95.1um, p = .001) and average CT (82.5um vs 88.7um, p = .001). COVID-19 patients had significantly lower subfoveal (64.0 vs 63.5, p = .02) and average CVI (63.5 vs 63.1, p = .02). Conclusion COVID-19 results in significantly thicker choroid with reduced relative vascularity. This may be attributable to increased vascular permeability secondary to inflammation, resulting in choroidal stromal edema.