Eye’s cornea can resist infection from novel coronavirus

 

New findings from researchers at Washington University School of Medicine in St. Louis suggest the eye’s cornea can resist infection from the novel coronavirus. Although the herpes simplex virus can infect the cornea and spread to other parts of the body in patients with compromised immune systems, and Zika virus has been found in tears and corneal tissue, SARS-CoV-2, the virus that causes COVID-19, does not appear to replicate in the human cornea.

The researchers have yet to determine, however, whether other tissue in and around the cornea, such as the tear ducts and the conjunctiva, are vulnerable to the virus.

The new findings are published Nov. 3 in the journal Cell Reports.

“Our findings do not prove that all corneas are resistant,. But every donor cornea we tested was resistant to the novel coronavirus. It’s still possible a subset of people may have corneas that support growth of the virus, but none of the corneas we studied supported growth of SARS-CoV-2.”

Jonathan J. Miner, MD, PhD, First Author

Miner, an assistant professor of medicine, of molecular microbiology and of pathology and immunology, teamed up with ophthalmologist Rajendra S. Apte, MD, PhD, to study mouse and human corneas exposed to the herpes simplex, Zika and SARS-CoV-2 viruses.

“Some COVID-19 patients get eye symptoms, such as conjunctivitis (pinkeye), but it’s not clear that the viral infection itself causes that; it could be related to secondary inflammation,” said Apte, the Paul A. Cibis Distinguished Professor in the John F. Hardesty Department of Ophthalmology & Visual Sciences. “The cornea and conjunctiva are known to have receptors for the novel coronavirus, but in our studies, we found that the virus did not replicate in the cornea.”

Prior research in human and mouse corneal tissue had demonstrated that Zika virus could be shed in tears, and the researchers wanted to learn whether the cornea might serve as an entry point for SARS-CoV-2. Apte, Miner and their colleagues tested that by exposing the eye tissue to the different viruses and observing whether they could grow in and replicate. They also identified key substances in corneal tissue that can promote or inhibit viral growth.

One inhibitor they identified is called interferon lambda. They found that interferon lambda prevented efficient growth of Zika virus and herpes simplex virus in the cornea. But with SARS-CoV-2, levels of the substance had not effect on whether the virus could replicate. It simply could not gain a foothold whether interferon lambda was present or not.

That’s reassuring to Apte, also a professor of developmental biology and of medicine, who said it suggests COVID-19 probably cannot be transmitted through a cornea transplant or similar procedures in the eye.

“Our data suggest that the novel coronavirus does not seem to be able to penetrate the cornea,” Apte said.

Miner added, however, that because of unknowns involving the tear ducts and the conjunctiva, it’s too soon to dismiss the importance of eye protection.

“It’s important to respect what this virus is capable of and take appropriate precautions,” he said. “We may learn that eye coverings are not necessary to protect against infection in the general community, but our studies really are just the beginning. We need larger clinical studies to help us better understand all the potential routes of SARS-CoV-2 transmission, including the eye.”

Source:
Washington University School of Medicine

Journal reference:
Miner, J.J., et al. (2020) HSV-1 and Zika Virus but Not SARS-CoV-2 Replicate in the Human Cornea and Are Restricted by Corneal Type III Interferon. Cell Reports. doi.org/10.1016/j.celrep.2020.108339.


Risks associated with eye-make up

Applying make-up is an everyday routine for millions of people worldwide. Even if a person only applies make-up once or twice a week, maintaining good make-up hygiene is essential in preventing skin irritations and serious eye infections.

How to practice good make-up hygiene

There are a number of simple but important steps that can help to prevent eye irritation and eye infections.

Renew your make-up every three months to reduce the risk of developing infections. This is particularly true in the case of eye make-up like mascaras or eyeliners. In some rare cases, women who have developed an eye infection from cosmetics have been temporarily or permanently blinded, according to the FDA. Some of these infections may stem from the make-up wands or brushes themselves.

 

Image Credit: Lucky Business / Shutterstock

Once a mascara wand or eyeliner brush comes into contact with the eyelashes, contamination of the applicator occurs as eyelashes naturally have bacteria on them. Over time, this contamination of both the brush and the container builds up and can lead to an increased risk of infection or allergic reactions. For this reason, sharing cosmetics is not advised at any time, as bacteria can harm another person even if the original user does not experience any reactions or infections themselves.

Fortunately, most people won’t experience any problems using make-up for longer than three months. If irritation does occur after using make-up products, it is essential to stop using the product immediately. If the irritation persists, medical attention should be sought.

Storing make-up products properly is also important. If cosmetics are stored in particularly hot conditions, for instance above 85°F (29°C), the preservatives in the products are at a higher risk of deteriorating.

Risks associated with eye-make up

It is important to remove make-up before sleeping. Ophthalmologist Dana Robaei published a case study in 2018 about a woman suffering from chronic foreign body sensation in both of her eyes. The article detailed the harmful effects that can occur after leaving mascara on overnight.

After examining the eyes, Robaei found subconjunctival mascara deposition beneath both eyelids. This was due to over 25 years of heavy mascara use without taking care to remove it properly. Small pieces of mascara had built up inside the eyelid and formed into solid concretions that were scratching the cornea, resulting in irritation and discomfort. The patient was left with permanent scarring on the cornea and on the eyelid after a surgical procedure to remove the built up concretions. Although Robaei clarifies it was a rare and extreme case, it nevertheless highlights the importance of removing eye make-up properly every night.

Other reports have been made about the risk of mascara-induced damage to the lacrimal drainage system, with one patient developing a dacryolith (a concretion usually comprising lipids, epithelial cells and other debris) loaded with mascara. Other reports in literature reviews on problems caused by mascara include eyelid dermatitis, infection keratitis, and mascaroma, among others.

Additionally, not all make-up applied to the eyes remains within the area of application. For instance, mascara can flake off and small particles travel into the eye, causing redness or irritation. In other cases, the eye can be scratched by make-up brushes or pencils that can then lead to serious eye infections. Ensuring that any applicator used near the eyes is clean can help to reduce the risk of scratch-induced infections. However, the trauma caused by scratches may still trigger problems or reactions.

Summary

As most make-up and cosmetic products undergo rigorous testing before being sold, the daily use of make-up is thought to pose minimal initial risk. It is when make-up is not removed properly, contaminated, or used when individual allergies are already apparent, that risks of infection, irritation and permanent damage to the application area increase.

A microbial study asked forty women to use one of two brands of non-waterproof mascara every day for three months. It was found that out of the 33 samples collected from the 40 women, microbial growth was present in over 36% of mascara containers.

As such, the need to practice good make-up hygiene is clear. Careful application of make-up around the eyes can reduce the risk of eye injury and subsequent irritation, infection, and loss of vision, in rare cases.

Sources

https://www.news-medical.net/health/Risks-Associated-with-Eye-Make-Up.aspx
http://www.scielo.br/pdf/abo/v79n6/0004-2749-abo-79-06-0411.pdf
journals.lww.com/…/…anifestations_of_Long_Term_Mascara_Use.29.aspx
https://wexnermedical.osu.edu/blog/eye-makeup-risks
https://www.aaojournal.org/article/S0161-6420(17)33788-0/fulltext
https://www.ajo.com/article/0002-9394(75)90798-9/pdf
www.sciencealert.com/mascara-make-up-remove-health-effects-dangerous-eyes
https://www.sciencedirect.com/science/article/pii/S1529183908003795