Due to the widespread impact of the COVID-19 pandemic, an in depth understanding of the mechanisms of SARS-CoV-2 infection and how it relates to ocular transmission is needed. Taken together, the current available data, supports that SARS-CoV-2 may either directly infect cells on the ocular surface, or virus can be carried through the nasolacrimal duct to infect the respiratory or gastrointestinal epithelium. Efforts to shield the ocular surface should be employed in conjunction with respiratory protection to reduce the transmission of SARS-CoV-2.
-The key proteins necessary for SARS-CoV-2 infection include Transmembrane Serine Protease 2 (TMPRSS2), CD147, Angiotensin-Converting Enzyme 2 (ACE2) and Cathepsin L (CTSL).
-The ocular surface and retina have variable expression of TMPRSS2, CD147, ACE2 and CTSL and appear to be susceptible to SARS-CoV-2 infection.
-Nasal epithelium is known to highly express TMPRSS2, CD147, ACE2 and CTSL.
-In addition to direct ocular infection, virus carried by tears through the nasolacrimal duct to nasal or gastrointestinal epithelium may represent a means of ocular inoculation.
-Efforts to shield the ocular surface and prevent drainage of virus from tears into nasal or gastrointestinal epithelium may prevent SARS-CoV-2 infection.