The Ocular Surface and the Coronavirus Disease 2019: Does a Dual ‘Ocular Route’ Exist?

Abstract

Coronavirus disease 2019 (COVID-19) is an important health problem that was defined as a pandemic by the World Health Organization on 11 March 2020. Although great concern has been expressed about COVID-19 infection acquired through ocular transmission, its underlying mechanism has not currently been clarified. In the current work, we analyzed and elucidated the two main elements that should be taken into account to understand the "ocular route", both from a clinical and molecular point of view. They are represented by the dynamism of the ocular surface system (e.g., the tear film turnover) and the distribution of ACE2 receptors and TMPRSS2 protein. Although it seems, at the moment, that there is a low risk of coronavirus spreading through tears, it may survive for a long time or replicate in the conjunctiva, even in absence of conjunctivitis signs, indicating that eye protection (e.g., protective goggles alone or in association with face shield) is advisable to prevent contamination from external droplets and aerosol.

Novel Insights into the Transmission of SARS-CoV-2 Through the Ocular Surface and its Detection in Tears and Conjunctival Secretions: A Review

“…The lacrimal drainage system acts as a physical self-cleaning system that clears pathogens from the ocular surface. However, this mechanism may prove counterproductive for SARS-CoV-2 infection, since passage of infected tears through the nasolacrimal drainage system may serve as an entry route of the virus from the infected ocular surface to the respiratory and digestive tract [24]. The opposite passage of the virus from the nasal and oral mucosa to the eye seems less likely, but cannot be ruled out entirely.…”

Safety Recommendations and Medical Liability in Ocular Surgery during the COVID-19 Pandemic: An Unsolved Dilemma

“…Shortly, this infectious disorder represented a global health problem of great impact on the lifestyle of various populations (e.g., during and after the lockdown period) [2] and on their ability to heal themselves. The easy transmissibility of SARS-CoV-2 quickly resulted in the suspension or sharp reduction of various ophthalmic activities considered non-urgent, including cataract surgery or some intraocular injections [3,4].…”

Multiparametric optical characterization of airborne dust with single particle extinction and scattering

“…Symptomatic, pre-symptomatic and asymptomatic individuals may expel virus-laden particles when coughing, sneezing, talking, or breathing, which may facilitate transmission (Asadi et al 2020). The epithelium of the human eye is a mucosal surface that may serve as a portal of SARS-CoV-2 transmission (Napoli et al 2020). Hoffmann et al (2020) demonstrated that binding of the SARS-CoV-2 surface-bound Spike protein (S) to angiotensin-converting enzyme-2 (ACE2) receptors and cleavage by serine protease TMPRSS2, enables host cellular entry.…”

“…Hoffmann et al (2020) demonstrated that binding of the SARS-CoV-2 surface-bound Spike protein (S) to angiotensin-converting enzyme-2 (ACE2) receptors and cleavage by serine protease TMPRSS2, enables host cellular entry. Because human ACE2 receptors and the TMPRSS2 protein are found in the conjunctiva and cornea, ocular transmission of airborne SARS-CoV-2 is highly plausible (Napoli et al 2020).…”