<p>The Role of the Ocular Tissue in SARS-CoV-2 Transmission</p>

Abstract

The current global pandemic of coronavirus disease 2019 (COVID-19) has affected over 21 million people and caused over half a million deaths within a few months. COVID-19 has become one of the most severe public health crises in recent years. Compared to other pathogenic coronaviruses, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is highly infectious. Due to the lack of specific and effective treatment or vaccines, disease prevention and early detection are essential for establishing guidelines to mitigate further spread. The potential role of the ocular system in COVID-19 is still not clear but it has gained increasing attention. Here, we reviewed both clinical and research evidence on the ocular manifestations associated with COVID-19, the presence of SARS-CoV-2 in ocular surface tissues and tears, and the potential role of the eye in contracting SARS-CoV-2.

Anti-SARS-Cov-2 IgA Response in Tears of COVID-19 Patients

“…Overall, the most common ocular manifestation of SARS-CoV-2 infection is unilateral or bilateral conjunctivitis or conjunctivitis-like signs and symptoms, which is similar to that observed in SARS-CoV-1 and HCoV-NL63 infections [36]. Other ocular manifestations include photophobia, redness, ocular secretions, chemosis, itching, foreign body sensation, dry eyes, follicular conjunctivitis, and episcleritis, all symptoms which may simulate other ocular diseases [37]. There has been only one study showing retinal changes in COVID-19 patients [38].…”

SARS‐CoV‐2 and COVID‐19 for the ophthalmologist

“…To reach the intraocular compartment from systemic circulation, the novel coronavirus could come either from the central retinal circulation, or anterior and posterior ciliary arteries. In contrast to documentary evidence of SARS‐CoV‐2 particles in the ocular surface and tears, 35,88,96,98‐100 so far only two studies have described detection of viral proteins or RNA in intraocular structures, more specifically the iris and trabecular meshwork, 101 as well as the retina 102 . Nevertheless, actual infectivity of these viral particles detected in ocular samples has not been demonstrated to date 103,104 …”

“…Indeed, ophthalmologists are at particular occupational risk, as SARS‐CoV‐2 is a respiratory virus transmitted primarily through contaminated liquid droplets exhaled by infected individuals 86,87 . In addition, the novel coronavirus and/or its RNA have also been recovered from the ocular tissue and tears of infected individuals, with conjunctivitis and other possible ocular changes being increasingly characterized in association with COVID‐19 88‐91 …”

“…The novel coronavirus may reach the eye through exogenous or endogenous routes. The exogenous route to the eye involves the ocular surface, particularly the conjunctiva, which expresses angiotensin converting enzyme receptor 2, one of the target proteins utilized by the virus to enter human cells 88,96 . From there, SARS‐CoV‐2 may reach the nasal mucosa (through the nasolacrimal epithelium), the gastrointestinal tract, and/or the systemic circulation, at times leaving conjunctivitis as a local manifestation of viral infection, 89,97 similar to other respiratory viruses.…”

“…Endogenous viral dissemination to the eye may involve extension of the infection from the upper respiratory tract through the nasolacrimal epithelium or viral shedding in tears secreted by an infected lacrimal gland 88,96 . Viral particles would then eventually reach the conjunctiva, occasionally leading to a picture consistent with viral conjunctivitis.…”