RT Journal Article SR Electronic T1 SARS-CoV-2 RNA and antibodies in tear fluid JF BMJ Open Ophthalmology JO BMJ Open Ophth FD BMJ Publishing Group Ltd SP e000733 DO 10.1136/bmjophth-2021-000733 VO 6 IS 1 A1 Astrid Muyldermans A1 Maria Bjerke A1 Thomas Demuyser A1 Deborah De Geyter A1 Ingrid Wybo A1 Oriane Soetens A1 Ilse Weets A1 Robert Kuijpers A1 Sabine D Allard A1 Denis PiƩrard A1 Peter P M Raus YR 2021 UL http://bmjophth.bmj.com/content/6/1/e000733.abstract AB Background/aims SARS-CoV-2 is highly contagious. More evidence concerning extrapulmonary transmission routes such as the eyes is urgently needed. Although the humoral immune response is important in the viral containment, the local response in tears has not yet been studied. The aim of our study was twofold: to assess the prevalence of both SARS-CoV-2 RNA and antibodies in tear fluid.Methods In a first series, nasopharyngeal sampling and tear sampling by Schirmer test strips were performed in 26 acutely ill patients with COVID-19 to assess the presence of SARS-CoV-2 RNA by reverse transcription PCR. In a second series, IgG and IgA responses to SARS-CoV-2 spike protein in serum and tear fluid of convalescent individuals (n=22) were compared with control individuals (n=15) by ELISA.Results SARS-CoV-2 RNA was detected in tears of 7/26 (26.9%) patients with COVID-19. None of them had ocular symptoms. Convalescent individuals displayed a significant higher ratio of IgG (p<0.0001) and IgA (p=0.0068) in tears compared with control individuals. A sensitivity of 77.3% and specificity of 93.3% was observed for IgG, and 59.1% and 100% for IgA.Conclusions Our results demonstrate the presence of SARS-CoV-2 RNA and a local IgG and IgA immune response in tear fluid. These data confirm the possibility of SARS-CoV-2 transmission through tear fluid and the importance of the eye as a first defence against SARS-CoV-2, indicating the potential of tears as a non-invasive surrogate for serum in monitoring the host immune response.All data relevant to the study are included in the article or uploaded as supplementary information.