Histopathological assessments reveal retinal vascular changes, inflammation and gliosis in patients with lethal COVID-19

PURPOSE: To assess for histopathological changes within the retina and the choroid and determine the long-term sequelae of the SARS-CoV-2 infection. DESIGN: Comparative analysis of human eyes. SUBJECTS: Eleven donor eyes from COVID-19 positive donors and similar age-matched donor eyes from patients with a negative test for SARS-CoV-2 were assessed. METHODS: Globes were evaluated ex-vivo with macroscopic, SLO and OCT imaging. Macula and peripheral regions were processed for epon-embedding and immunocytochemistry MAIN OUTCOME MEASURES: Retinal thickness and histopathology, detection of SARS-CoV-2 Spike protein, changes in vascular density, gliosis, and degree of inflammation. RESULTS: Fundus analysis shows hemorrhagic spots and increased vitreous debris in several of the COVID-19 eyes compared to the control. OCT based measurements indicated an increased trend in retinal thickness in the COVID-19 eyes, however the difference was not statistically significant. Histology of the retina showed presence of hemorrhages and central cystoid degeneration in several of the donors. Whole mount analysis of the retina labeled with markers showed changes in retinal microvasculature, increased inflammation, and gliosis in the COVID-19 eyes compared to the controls. The choroidal vasculature displayed localized changes in density and signs of increased inflammation in the COVID-19 samples. CONCLUSIONS: In situ analysis of the retinal tissue suggested that there are severe subclinical abnormalities that could be detected in the COVID-19 eyes. This study provides a rationale for evaluating the ocular physiology of patients that have recovered from COVID-19 infections to further understand the long-term effects caused by this virus.