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The ocular surface, coronaviruses and COVID-19.
Clin Exp Optom. 2020 07; 103(4):418-424.CE

Abstract

The ocular surface has been suggested as a site of infection with Coronavirus-2 (SARS-CoV-2) responsible for the coronavirus disease-19 (COVID-19). This review examines the evidence for this hypothesis, and its implications for clinical practice. Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), responsible for the COVID-19 pandemic, is transmitted by person-to-person contact, via airborne droplets, or through contact with contaminated surfaces. SARS-CoV-2 binds to angiotensin converting enzyme-2 (ACE2) to facilitate infection in humans. This review sets out to evaluate evidence for the ocular surface as a route of infection. A literature search in this area was conducted on 15 April 2020 using the Scopus database. In total, 287 results were returned and reviewed. There is preliminary evidence for ACE2 expression on corneal and conjunctival cells, but most of the other receptors to which coronaviruses bind appear to be found under epithelia of the ocular surface. Evidence from animal studies is limited, with a single study suggesting viral particles on the eye can travel to the lung, resulting in very mild infection. Coronavirus infection is rarely associated with conjunctivitis, with occasional cases reported in patients with confirmed COVID-19, along with isolated cases of conjunctivitis as a presenting sign. Coronaviruses have been rarely isolated from tears or conjunctival swabs. The evidence suggests coronaviruses are unlikely to bind to ocular surface cells to initiate infection. Additionally, hypotheses that the virus could travel from the nasopharynx or through the conjunctival capillaries to the ocular surface during infection are probably incorrect. Conjunctivitis and isolation of the virus from the ocular surface occur only rarely, and overwhelmingly in patients with confirmed COVID-19. Necessary precautions to prevent person-to-person transmission should be employed in clinical practice throughout the pandemic, and patients should be reminded to maintain good hygiene practices.

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Authors+Show Affiliations

Willcox MD
School of Optometry and Vision Science, The University of New South Wales, Sydney, New South Wales, Australia.
Walsh K
Centre for Ocular Research & Education (CORE), School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada.
Nichols JJ
School of Optometry, University of Alabama at Birmingham, Birmingham, Alabama, USA.
Morgan PB
Eurolens Research, Division of Pharmacy and Optometry, The University of Manchester, Manchester, UK.
Jones LW
Centre for Ocular Research & Education (CORE), School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada.

MeSH

Angiotensin-Converting Enzyme 2AnimalsBetacoronavirusCOVID-19ConjunctivitisCoronavirus InfectionsEyeHumansPandemicsPeptidyl-Dipeptidase APneumonia, ViralReceptors, VirusSARS-CoV-2

Pub Type(s)

Journal Article
Review

Language

eng

PubMed ID

32406140

Citation

Willcox, Mark Dp, et al. "The Ocular Surface, Coronaviruses and COVID-19." Clinical & Experimental Optometry, vol. 103, no. 4, 2020, pp. 418-424.
Willcox MD, Walsh K, Nichols JJ, et al. The ocular surface, coronaviruses and COVID-19. Clin Exp Optom. 2020;103(4):418-424.
Willcox, M. D., Walsh, K., Nichols, J. J., Morgan, P. B., & Jones, L. W. (2020). The ocular surface, coronaviruses and COVID-19. Clinical & Experimental Optometry, 103(4), 418-424. https://doi.org/10.1111/cxo.13088
Willcox MD, et al. The Ocular Surface, Coronaviruses and COVID-19. Clin Exp Optom. 2020;103(4):418-424. PubMed PMID: 32406140.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - The ocular surface, coronaviruses and COVID-19. AU - Willcox,Mark Dp, AU - Walsh,Karen, AU - Nichols,Jason J, AU - Morgan,Philip B, AU - Jones,Lyndon W, Y1 - 2020/05/13/ PY - 2020/04/21/received PY - 2020/04/22/accepted PY - 2020/5/15/pubmed PY - 2020/7/15/medline PY - 2020/5/15/entrez KW - ACE2 KW - COVID-19 KW - SARS-CoV-2 KW - conjunctivitis KW - coronavirus KW - ocular surface SP - 418 EP - 424 JF - Clinical & experimental optometry JO - Clin Exp Optom VL - 103 IS - 4 N2 - The ocular surface has been suggested as a site of infection with Coronavirus-2 (SARS-CoV-2) responsible for the coronavirus disease-19 (COVID-19). This review examines the evidence for this hypothesis, and its implications for clinical practice. Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), responsible for the COVID-19 pandemic, is transmitted by person-to-person contact, via airborne droplets, or through contact with contaminated surfaces. SARS-CoV-2 binds to angiotensin converting enzyme-2 (ACE2) to facilitate infection in humans. This review sets out to evaluate evidence for the ocular surface as a route of infection. A literature search in this area was conducted on 15 April 2020 using the Scopus database. In total, 287 results were returned and reviewed. There is preliminary evidence for ACE2 expression on corneal and conjunctival cells, but most of the other receptors to which coronaviruses bind appear to be found under epithelia of the ocular surface. Evidence from animal studies is limited, with a single study suggesting viral particles on the eye can travel to the lung, resulting in very mild infection. Coronavirus infection is rarely associated with conjunctivitis, with occasional cases reported in patients with confirmed COVID-19, along with isolated cases of conjunctivitis as a presenting sign. Coronaviruses have been rarely isolated from tears or conjunctival swabs. The evidence suggests coronaviruses are unlikely to bind to ocular surface cells to initiate infection. Additionally, hypotheses that the virus could travel from the nasopharynx or through the conjunctival capillaries to the ocular surface during infection are probably incorrect. Conjunctivitis and isolation of the virus from the ocular surface occur only rarely, and overwhelmingly in patients with confirmed COVID-19. Necessary precautions to prevent person-to-person transmission should be employed in clinical practice throughout the pandemic, and patients should be reminded to maintain good hygiene practices. SN - 1444-0938 UR - https://www.unboundmedicine.com/medline/citation/32406140/The_ocular_surface_coronaviruses_and_COVID_19_ DB - PRIME DP - Unbound Medicine ER -