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.

Evaluation of Retinal Vascularity Index in Patients with COVID-19: A Case-Control Study.

INTRODUCTION: The purpose of this study was to evaluate the impact of COVID-19 infection on retinal microvasculature by topographically mapping the retinal arteriole-to-venule ratio (AVR). METHODS: In a comparative cross-sectional case-control study, fundus photos were obtained in COVID-19-infected patients and healthy controls. AVT was measured over 16 points across the retina using retinal vascularity index (RVI)-a novel semi-automated computerized parameter based on retinal vasculature. RESULTS: A total of 51 COVID-19-positive patients and 65 healthy controls were enrolled in the study. Overall, the mean RVI of all 16 points across the retina was 0.34 ± 0.02 in patients with COVID-19 and 0.33 ± 0.02 in control subjects (p = 0.64). Out of the 16 points being measured, three points had a statistically significant greater value in patients with COVID compared to normal controls. CONCLUSION: Localised greater RVI values were found in some of the points in COVID-19-positive patients, which likely indicates a more focal change of the vasculature.