The Eye: A Possible New Route of Infection in COVID-19

[...]the close anatomical link between the eye and the respiratory tract enables viruses to be drained down through the nasolacrimal duct to the upper respiratory tract and cause infection. 1 Interestingly, the epithelial receptors of ocular and respiratory tissue share a similar structure that might explain the ocular tropism of the respiratory viruses. 1 Although ocular diseases have been commonly reported with principal respiratory viruses, such as adenovirus, influenza virus, respiratory syncytial virus, and rhinovirus, they are rarely reported with coronaviruses (CoVs). [...]all these observations put a great emphasis on the importance of using appropriate eye protection to prevent transmission of infection between patients and health care professionals. The low frequency of conjunctivitis and corneal involvement in COVID-19 patients could be explained with the fact that the level of ACE2 expression in ocular tissues is much less compared with other organs, such as the lungs and kidneys. 6 Interestingly, conjunctivitis has been reported with a higher frequency in patients with severe COVID-19 compared with non-severe COVID-19, 3% vs 0.7%, respectively. 9 This could be because patients with severe COVID-19 disease tend to have multi-organ involvement. [...]conjunctivitis might indicate poor outcome in COVID-19 patients with respiratory illness.