Infectious Disorders – Drug Targets     Send Orders for Reprints to reprints@benthamscience.net 480 Infectious Disorders - Drug Targets, 2021, 21, 480-483 PERSPECTIVE Ocular COVID-19: Eyes as a Reservoir to Conceal and Spread SARS- CoV-2 Abdul Mannan Baig 1,* , Saara Ahmad 1 , Areeba Khaleeq 1 , Hamna Rafique 1 , Shafiqa Rajput 1 , Mehaer Angez 1 , Ayesha Hameed 1 , Talha Nawaz 1 and Preet Katyara 1 1 Department of Biological and Biomedical Sciences, Aga Khan University, Karachi, Pakistan ARTICLE HISTORY Received: March 27, 2020 Revised: July 07, 2020 Accepted: July 07, 2020 DOI: 10.2174/1871526520999200729182242 Abstract: Ocular tissues can serve as a reservoir for the SARS-CoV-2 virus which can not only cause conjunctivitis but also serve as a source of infection transmission to others. Additionally, the eye and its tear drainage apparatus can track the SARS-CoV-2 from the eye into the respiratory tract of the patient. The potential ocular presence of the SARS-CoV-2 in the eye of a patient can tar- get ACE2 receptors in the endothelium of the conjunctival vessels and use the lacrimal sac a poten- tial space to evade immune detection and clinical isolation. The recently reported case of COVID-19 after the acquisition of SARS-CoV-2 from a COVID-19 patient should alert the health- care professionals dealing with COVID-19 patients that wearing masks alone cannot guarantee pro- tection against infection transmission. Further studies, like isolation of SARS-CoV-2 from the eyes of patients with COVID-19, are needed to identify the eyes as a potential source of SARS-CoV-2 infection transmission. Keywords: COVID-19, SARS-CoV-2, ACE2 receptors, ocular viral infections, conjunctivitis, respiratory, . 1. INTRODUCTION With 9,421,922 confirmed cases and around 481,430 deaths worldwide, as of June 24, 2020, the coronavirus caus- ing COVID-19 outbreak has led to a once in a century pan- demic we have feared [1]. The pandemic has rapidly be- come the defining struggle of 2020 and demands immediate attention. Originating in the wet markets of Wuhan, China, the positive-sense single-stranded RNA of the coronaviridae family is believed to take a reservoir in pangolins and have jumped species from bats to humans [2, 3]. The combination of droplet mode of transmission and asymptomatic incuba- tion period of about a week has led to rapid international spread [4]. Despite rigorous global containment and quaran- tine efforts, significant morbidity and mortality has been ob- served [1, 5, 6]. With the scientists still trying to find ways to combat the faster rate of transmission of the SARS-CoV- -2 and attempting to unravel the pathogenesis of the recur- rences seen in COVID-19 patients, there are no signs that spread of the virus is slowing down. The devastating effects of the COVID 19 outbreak have not been limited to health but have also reached the world economy and social well-be- ing. With no vaccine or specific pharmaceutical therapy avail- able to target the SARS-Co-V-2, efforts must be made to find effective ways of halting this rapid spread. To achieve this, understanding and elaborating on the pathways this virus takes to spread becomes crucial. It is now known that the main mode of transmission of this virus is respiratory droplets, contaminated surfaces, and close person * Address correspondence to this author at the Department of Biological and Biomedical Sciences, Aga Khan University, Karachi, Pakistan; Tel: +92-(0)333-2644-246; E-mail: abdul.mannan@aku.edu to person contact [7-9]. However, recent reports have started identifying eyes as a possible route of transmission of the virus [9]. Initial rays of light were shone upon this new in- triguing information when one of the first reported deaths due to the SARS-Co-V-2 virus was that of an ophthalmolo- gist in December 2019 [10, 11]. Since then, this new path- way of spread has gained significant traction. Various inferences have been made to explain and justi- fy this possible way of virus transmission. One of the most widely talked about justification revolves around the pres- ence of genes expressing ACE2 in corneal and conjunctival epithelium cells [12]. It has been previously established that SARS-CoV-2 makes use of ACE2 receptors to gain entry in- to the cells and exert its pathogenic effects [8]. It is, there- fore, reasonable to infer that these receptors can act as open doors for the virus allowing them entry into the ocular struc- tures. Given the devastating effects of COVID-19, it becomes imperative that all scientific focus shifts to slowing its spread to minimize the damage as much as we can. To do that, understanding of the pathway this virus takes to culti- vate more hosts becomes a crucial first step. We, following a thorough review of the present literature, hope to inch closer to that goal. 2. CURRENT KNOWLEDGE OF THE PATHOGENE- SIS OF SARS-COV-2 INFECTION BASED ON THE DISTRIBUTION OF ITS MOLECULAR TARGET ACE2 The morbidity and mortality rates observed in COVID-19 are thought to be based on the tissue distribution of the host receptor ACE2, which reacts with the recep- 2212-3989/21 $65.00+.00 © 2021 Bentham Science Publishers