SARS-CoV-2 and the eye: A relationship for a possible prognostic tool in COVID-19 patients

Abstract 
Purpose: In December 2019 there was the first report about a new viral infection in Wuhan, China. The new virus was taxonomically designed as Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) causing the coronavirus disease 2019 (COVID-19). SARS-CoV-2 uses the angiotensin-converting enzyme 2 (ACE2) receptor for cell invasion, which is expressed in different tissues including lungs, small intestine, testicles, kidneys, brain, and the eye. The purpose of this article is to review the available information on the relationship of COVID-19 with the eye, as well as evaluating the possible usefulness of ocular diagnostic tests to help in the diagnosis and/or monitoring of patients with this disease.
Methods: We performed a retrospective review of relevant articles from November 2019 to April 2020.
Results: Ocular infection by SARS-CoV-2 is still controversial; nevertheless, the possibility of being a viral reservoir has been suggested, increasing the likelihood of infection. Some reports demonstrated the presence of SARS-CoV-2 in tears, and previously published data suggest a pathological increase of cytokine concentrations in COVID-19 patients; the cytokine release syndrome or cytokine storm contributes to lung and central nervous system damage. The usefulness of tears for the measurement of inflammatory cytokines in various diseases is well known, in particular IL-6, which has been correlated to the severity of COVID-19.
Conclusion: Considering that the IL-6 signaling cascade may be activated in patients with COVID-19, makes it an excellent target for diagnostic and/or monitoring purposes.