Seroprevalence of immunoglobulin M and G antibodies against SARS-CoV-2 in ophthalmic patients

Using serological test to estimate the prevalence and infection potential of coronavirus disease 2019 in ocular diseases patients help understand the relationship between ocular diseases and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. We conducted a cross-sectional study assaying the IgG and IgM antibodies in 1331 individuals with ocular diseases by using a magnetic chemiluminescence enzyme immunoassay kit, during the period from February 2020 to May 2020. In our study, the seroposivity in total ocular disease patients was 0.83% (11/1331). The patients with different ocular diseases including xerophthalmia, keratitis, conjunctival cyst, cataract, glaucoma, refractive error, strabismus and others had seroposivity of 2.94%, 12.5%, 25%, 4.41%, 2.63%, 1.6%, 2.22% and 0%, respectively. Among that, two ocular surface disease groups (keratitis and conjunctival cyst) had higher seroprevalence compared with others. All the participants were reverse transcription polymerase chain reaction negative for SARS-CoV-2 from throat swabs. Our study evaluated the seroprevalence in patients with different ocular diseases, which will help us understand the relationship between ocular disease and SARS-CoV-2 infection. Furthermore, the serological test for the presence of IgM and/or IgG antibodies against SARS-CoV-2 might provide accurate estimate of the prevalence of SARS-CoV-2 infection in patients with ocular diseases.

COVID-19 receptor ACE2 is expressed in human conjunctival tissue, expecially in diseased conjunctival tissue

COVID-19 virus has currently caused major outbreaks worldwide. ACE2 is a major cellular-entry receptor for the COVID-19 virus. Although ACE2 is known to be expressed in many organs, whether it is expressed by the conjunctival tissue is largely unknown. Human conjunctival tissues from 68 subjects were obtained, which included 10 subjects with conjunctival nevi, 20 subjects with conjunctivitis, 9 subjects with conjunctival papilloma, 16 subjects with conjunctival cyst, 7 subjects with conjunctival polyps, and 6 ocular traumas as normal subjects. Expression of ACE2 was evaluated by immunohistochemistry, immunofluorescence, reverse transcriptase-quantitative polymerase chain reaction, and western blot assay. We observed the expression of ACE2 by conjunctival tissues, expecially in conjunctival epithelial cells. ACE2 was significantly (p<0.001) overexpressed in conjunctival cells obtained from subjects with conjunctivitis, conjunctival nevi, conjunctival papilloma, conjunctival cyst, and conjunctival polyps epithelial cells when compared to that in conjunctival epithelial cells obtained from control subjects. Collectively, clinical features of reported COVID-19 patients combined with our results indicate that COVID-19 is likely to be transmitted through the conjunctiva.