Presumed SARS-CoV-2 Viral Particles in the Human Retina of Patients With COVID-19.

Importance: The presence of the SARS-CoV-2 virus in the retina of deceased patients with COVID-19 has been suggested through real-time reverse polymerase chain reaction and immunological methods to detect its main proteins. The eye has shown abnormalities associated with COVID-19 infection, and retinal changes were presumed to be associated with secondary microvascular and immunological changes. Objective: To demonstrate the presence of presumed SARS-CoV-2 viral particles and its relevant proteins in the eyes of patients with COVID-19. Design, Setting, and Participants: The retina from enucleated eyes of patients with confirmed COVID-19 infection were submitted to immunofluorescence and transmission electron microscopy processing at a hospital in São Paulo, Brazil, from June 23 to July 2, 2020. After obtaining written consent from the patients' families, enucleation was performed in patients deceased with confirmed SARS-CoV-2 infection. All patients were in the intensive care unit, received mechanical ventilation, and had severe pulmonary involvement by COVID-19. Main Outcomes and Measures: Presence of presumed SARS-CoV-2 viral particles by immunofluorescence and transmission electron microscopy processing. Results: Three patients who died of COVID-19 were analyzed. Two patients were men, and 1 was a woman. The age at death ranged from 69 to 78 years. Presumed S and N COVID-19 proteins were seen by immunofluorescence microscopy within endothelial cells close to the capillary flame and cells of the inner and the outer nuclear layers. At the perinuclear region of these cells, it was possible to observe by transmission electron microscopy double-membrane vacuoles that are consistent with the virus, presumably containing COVID-19 viral particles. Conclusions and Relevance: The present observations show presumed SARS-CoV-2 viral particles in various layers of the human retina, suggesting that they may be involved in some of the infection's ocular clinical manifestations.

Severe acute respiratory Syndrome-Coronavirus-2: Can it be detected in the retina?

BACKGROUND/OBJECTIVES: The systemic organ involvement of SARS-CoV-2 needs to be thoroughly investigated including the possibility of an ocular reservoir in humans. To examine retinal tissues and vitreous for histopathology and SARS-CoV-2 presence with regard to possible effects on the human retina and/ or vitreous. We performed histopathological analyses and quantitative (q)RT-PCR-testing for SARS-CoV-2 RNA on retinal tissues and vitreous of COVID-19 postmortem donors. SUBJECTS/METHODS: Included in this study were 10 eyes of 5 deceased COVID-19 patients. The diagnosis of SARS-CoV-2 infection was confirmed via pharyngeal swabs and broncho-alveolar fluids. The highest level of personal protective equipment (PPE) and measures was employed during fluid-tissue procurement and preparation. Histopathological examinations and qRT-PCR-testing were carried out for all retinal tissues and vitreous fluids. RESULTS: The histopathological examinations revealed no signs of morphologically identifiable retinal inflammation or vessel occlusions based on hematoxylin and eosin stains. By qRT-PCRs, we detected no significant level of viral RNA in human retina and vitreous. CONCLUSIONS: In this study, no significant level of SARS-CoV-2-RNA was detected in the human retinal and vitreous fluid samples of deceased COVID-19 patients. Histopathological examinations confirmed no morphological sign of damage to retinal vasculature or tissues. Further studies are needed to confirm or refute the results.

Retinal involvement and ocular findings in COVID-19 pneumonia patients.

Changes in immune and coagulation systems and possible viral spread through the blood-brain barrier have been described in SARS-CoV-2 infection. In this study, we evaluated the possible retinal involvement and ocular findings in severe COVID-19 pneumonia patients. A cross-sectional study was conducted on 46 patients affected by severe COVID-19 who were hospitalized in one intensive care unit (ICU) and in two infectious disease wards, including bedside eye screening, corneal sensitivity assessment and retinography. A total of 43 SARS-CoV-2-positive pneumonia patients affected with COVID-19 pneumonia were included, including 25 males and 18 females, with a median age of 70 years [IQR 59-78]. Except for one patient with unilateral posterior chorioretinitis of opportunistic origin, of whom aqueous tap was negative for SARS-CoV-2, no further retinal manifestation related to COVID-19 infection was found in our cohort. We found 3 patients (7%) with bilateral conjunctivitis in whom PCR analysis on conjunctival swabs provided negative results for SARS-CoV-2. No alterations in corneal sensitivity were found. We demonstrated the absence of retinal involvement in SARS-CoV-2 pneumonia patients. Ophthalmologic evaluation in COVID-19, particularly in patients hospitalized in an ICU setting, may be useful to reveal systemic co-infections by opportunistic pathogens.

SARS-CoV-2 Targeting the Retina: Host-virus Interaction and Possible Mechanisms of Viral Tropism.

Background: Coronavirus disease 2019 (COVID-19) is caused by Severe Acute Respiratory Syndrome Coronavirus 2 10 (SARS-CoV-2). Recent studies demonstrated not only retinal impairments but also detected SARS-CoV-2 in the retina of patients with COVID-19. Purpose: This letter discusses the retinal tropism of SARS-CoV-2, describing possible routes for this coronavirus to reach the retina and cellular mechanisms involved in the retinal cell infection. Conclusions: Determining how SARS-CoV-2 can affect the retinal tissue is essential for the development of new therapeutic strategies and preventive measures, as well as for understanding the possible relationship between COVID-19 damage to the retina and to the brain.