SARS-COV-2 and Ocular Surface: From Physiology to Pathology, a Route to Understand Transmission and Disease

Coronaviruses gained public attention during the severe acute respiratory syndrome (SARS) outbreak in East Asia in 2003 and spread of Middle Eastern respiratory syndrome (MERS) in 2012. Direct human-to-human contact and droplet are the main methods of transmission. Viral stability in aerosols on different surfaces supports evidence on indirect viral acquisition from fomites through the mucous membranes of the mouth, nose, and eyes. Given the pandemic circumstances, the level of evidence in COVID-19 and ophthalmology regarding eye infection, conjunctival transmission, and viral shedding through tears is insufficient. Presently, conjunctival transmission of coronaviruses has not been confirmed and remains controversial. Considering the physiology of the lacrimal system and ocular surface, the eyes are considered an immunoprotective site, with several antiviral molecules and anti-inflammatory proteins. Nevertheless, they represent an interface with the exterior world and face daily putative aggressors. Understanding the host’s ocular surface immunological and protective environment is crucial to clarify the potential of the conjunctiva as an entry route for SARS-CoV-2 and as part of this viral infection. We will discuss hypothetical ocular surface transmission mechanisms and related counterarguments addressed to both angiotensin-converting enzyme 2 receptors found on the conjunctival and corneal epithelia and lactoferrin, lysozyme, lipocalin and secretory IgA levels in the tear film. Hopefully, we will promote better understanding of this organ in COVID-19 infection and the potential transmission route that can be helpful in setting recommendations on best practices and protective guidelines to mitigate the disease spread.

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Identification of effective spreaders in contact networks using dynamical influence

Applied Network Science ◽

10.1007/s41109-021-00351-0 ◽

2021 ◽

Vol 6 (1) ◽

Author(s):

Ruaridh A. Clark ◽

Malcolm Macdonald

Keyword(s):

Disease Transmission ◽

Average Rate ◽

Laplacian Matrix ◽

Disease Spread ◽

Eigenvector Centrality ◽

Contact Networks ◽

Human Contact ◽

Spread Dynamics ◽

Definition Of ◽

High Degree

AbstractContact networks provide insights on disease spread due to the duration of close proximity interactions. For systems governed by consensus dynamics, network structure is key to optimising the spread of information. For disease spread over contact networks, the structure would be expected to be similarly influential. However, metrics that are essentially agnostic to the network’s structure, such as weighted degree (strength) centrality and its variants, perform near-optimally in selecting effective spreaders. These degree-based metrics outperform eigenvector centrality, despite disease spread over a network being a random walk process. This paper improves eigenvector-based spreader selection by introducing the non-linear relationship between contact time and the probability of disease transmission into the assessment of network dynamics. This approximation of disease spread dynamics is achieved by altering the Laplacian matrix, which in turn highlights why nodes with a high degree are such influential disease spreaders. From this approach, a trichotomy emerges on the definition of an effective spreader where, for susceptible-infected simulations, eigenvector-based selections can either optimise the initial rate of infection, the average rate of infection, or produce the fastest time to full infection of the network. Simulated and real-world human contact networks are examined, with insights also drawn on the effective adaptation of ant colony contact networks to reduce pathogen spread and protect the queen ant.

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Tear Proteomics Study of Dry Eye Disease: Which Eye Do You Adopt as the Representative Eye for the Study?

International Journal of Molecular Sciences ◽

10.3390/ijms22010422 ◽

2021 ◽

Vol 22 (1) ◽

pp. 422

Author(s):

Ming-Tse Kuo ◽

Po-Chiung Fang ◽

Shu-Fang Kuo ◽

Alexander Chen ◽

Yu-Ting Huang

Keyword(s):

Dry Eye ◽

Ocular Surface ◽

Tear Film ◽

Dry Eye Disease ◽

Eye Disease ◽

Mechanistic Studies ◽

Clinical Tests ◽

Tear Proteins ◽

Proteomic Data ◽

Surface Performance

Most studies about dry eye disease (DED) chose unilateral eye for investigation and drew conclusions based on monocular results, whereas most studies involving tear proteomics were based on the results of pooling tears from a group of DED patients. Patients with DED were consecutively enrolled for binocular clinical tests, tear biochemical markers of DED, and tear proteome. We found that bilateral eyes of DED patients may have similar but different ocular surface performance and tear proteome. Most ocular surface homeostatic markers and tear biomarkers were not significantly different in the bilateral eyes of DED subjects, and most clinical parameters and tear biomarkers were correlated significantly between bilateral eyes. However, discrepant binocular presentation in the markers of ocular surface homeostasis and the associations with tear proteins suggested that one eye’s performance cannot represent that of the other eye or both eyes. Therefore, in studies for elucidating tear film homeostasis of DED, we may lose some important messages hidden in the fellow eye if we collected clinical and proteomic data only from a unilateral eye. For mechanistic studies, it is recommended that researchers collect tear samples from the eye with more severe DED under sensitive criteria for identifying the more severe eye and evaluating the tear biochemical and proteomic markers with binocular concordance drawn in prior binocular studies.

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OCULAR SURFACE DRYING AND TEAR FILM OSMOLARITY IN THYROID EYE DISEASE

Acta Ophthalmologica ◽

10.1111/j.1755-3768.1983.tb01401.x ◽

2009 ◽

Vol 61 (1) ◽

pp. 108-116 ◽

Cited By ~ 113

Author(s):

JEFFREY P. GILBARD ◽

R. LINSY FARRIS

Keyword(s):

Ocular Surface ◽

Tear Film ◽

Thyroid Eye Disease ◽

Eye Disease ◽

Surface Drying

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Low-Tech Detection of Tear Film-Related Diseases of the Ocular Surface

Lacrimal Gland, Tear Film, and Dry Eye Syndromes 2 - Advances in Experimental Medicine and Biology ◽

10.1007/978-1-4615-5359-5_119 ◽

1998 ◽

pp. 845-851

Author(s):

Maurizio Rolando ◽

Salvatore Alongi ◽

Angelo Macrì ◽

Marco Schenone ◽

Giovanni Calabria

Keyword(s):

Ocular Surface ◽

Tear Film

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Effects of Smoking on Tear Film and Ocular Surface

Korean Journal of Ophthalmology ◽

10.3341/kjo.2005.19.1.18 ◽

2005 ◽

Vol 19 (1) ◽

pp. 18 ◽

Cited By ~ 34

Author(s):

Kyung-Chul Yoon ◽

Byoung-Yong Song ◽

Man-Seong Seo

Keyword(s):

Ocular Surface ◽

Tear Film

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Diagnosis and Treatment Methods for Ocular Surface Disease in Glaucoma

European Ophthalmic Review ◽

10.17925/eor.2014.08.01.40 ◽

2014 ◽

Vol 08 (01) ◽

pp. 40

Author(s):

Gemma C M Rossi ◽

Keyword(s):

Ocular Surface ◽

Diagnostic Tests ◽

Benzalkonium Chloride ◽

Tear Film ◽

Daily Practice ◽

Ocular Surface Disease ◽

Anterior Surface ◽

Treatment Methods ◽

Associated Diseases

Glaucoma and ocular surface disease (OSD) are often concomitant disorders (OSD is the consequence of a tear film dysfunction that may be due to several conditions). The aims of the paper are to suggest a sequence of diagnostic tests easy to perform in daily practice, both subjective and objective, to detect the onset of the OSD; and, second, to propose how to prevent and, if the case, how to manage the OSD. Briefly, tear film break-up time (TF-BUT) and corneal/conjunctival staining are suggested to detect the main signs of OSD. In terms of therapy, the long-term exposure to benzalkonium chloride (BAK) should be minimised, preferring non-BAK-preserved or BAK-free glaucoma medications, where available, as well as fixed combinations. The treatment of associated diseases of the anterior surface may reduce signs; use of non BAK-preserved tears may reduce symptoms.

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