How the COVID-19 omicron and delta variants could affect your eyes

This article will be updated as new information becomes available.

• As of early January, nearly all new COVID-19 cases in the U.K. and U.S. were caused by the omicron variant.

• The World Health Organization labeled omicron a "variant of concern" on November 26, 2021. Since then, omicron has been detected in more than 110 countries.

• Like other coronavirus variants, omicron and delta may be able to cause certain eye-related symptoms, but we don't know for sure yet.

• Vaccines are less effective against the omicron and delta variants, but they're still your best form of protection.

• An eye test may soon be able to help detect cases of long-haul COVID.

The COVID-19 omicron variant was discovered in November 2021, and it didn't take long to spread across most of the world. Whenever it's detected in a new location, it usually takes over delta variant infections and becomes the dominant COVID strain in a matter of weeks.

The CDC estimates that more than 90% of new COVID cases in America are now caused by omicron infections, as of January 1, 2022.

At this point, it's still too early to know how the newly discovered omicron variant might affect your eyes or vision. And that isn't the only thing we don't know about omicron.

We're still waiting for detailed information about:

• How easily omicron spreads.

• Exactly how well COVID-19 vaccines protect against omicron.

• How severe of an illness it causes compared to other variants.

Early data suggests that the omicron variant could cause a more mild form of COVID-19 than delta and other variants. But that doesn't mean you should let your guard down.

"All variants of COVID-19 … can cause severe disease or death, in particular for the most vulnerable people," the World Health Organization notes.

They emphasize that "prevention is always key," no matter how omicron plays out.

We don't know for sure — yet. Previous strains of COVID could cause eye-related symptoms, but there isn't enough scientific data available right now to say with certainty that delta does the same.

There have been isolated reports of delta infections causing eye symptoms, including one fully vaccinated Kentuckian who had bloodshot eyes and flu-like symptoms, and a five-year-old in Mississippi who showed signs of conjunctivitis.

Although not nearly as common as symptoms like cough and fever, other strains of the coronavirus were capable of causing:

• Red, bloodshot eyes
• Pink eye (conjunctivitis)
• Sore eyes
• Itchy eyes
• Blurry vision
• Sensitivity to light

It isn't a stretch to think that some delta infections are capable of causing similar eye symptoms, but, like other aspects of delta, we need to wait for more information.

While each infection is different, delta seems to be causing slightly different symptoms overall than earlier forms of COVID.

"It seems like cough and loss of smell are less common," said Dr. Inci Yildirim, a  pediatric infectious disease specialist at Yale Medicine, in an article about the delta variant. "And headache, sore throat, runny nose and fever are present based on the most recent surveys in the U.K., where more than 90% of the cases are due to the Delta strain."

If a set of symptoms that includes runny nose, sore throat and headache sounds familiar, it's because many delta infection symptoms resemble a bad case of hay fever — seasonal allergies — more than any other strain.

This is where eye-related symptoms could get even more confusing.

If you have bad seasonal allergies, you probably know how much allergies can affect your eyes. Red, bloodshot eyes are a hallmark symptom; itchiness, watering and even blurry vision are also common.

And while "classic" COVID symptoms are becoming less common, they can still show up. Cough, loss of taste or smell, and certain gastrointestinal symptoms still occur, but they're becoming less likely.

The three most widely available COVID-19 vaccines — Pfizer, Moderna and Johnson & Johnson — will still protect you against the delta variant, but not as effectively as they did against previous strains. Fortunately, studies continue to show that these "breakthrough" cases are less common and less severe, on average.

As delta finds ways to infect more young people than earlier strains, a rare but serious complication of COVID is also expected to be on the rise.

MIS-C — multisystem inflammatory syndrome in children — can cause vital organs and other parts of the body to become inflamed. It shares similarities with Kawasaki disease, a condition uncovered earlier in the pandemic.

We don't currently know why MIS-C happens to some children.

Symptoms of MIS-C can vary. It can also cause red, bloodshot eyes, but like COVID-19, it's unlikely that would be the only symptom. Additional symptoms occur alongside a fever, according to the CDC.

In addition to a fever, MIS-C symptoms can include:

• Bloodshot eyes
• Headache
• Abdominal pain
• Chest pain or tightness
• Diarrhea
• Fatigue
• Neck pain
• Low blood pressure
• Rash
• Vomiting

As of August 22, 2021 there have been 4,661 verified cases of MIS-C in the U.S., with others under investigation. Forty-one children have died from the complication.

While rare, the CDC recommends seeking emergency care if you notice symptoms such as difficulty breathing, chest pain or pressure, pale skin or any other severe symptoms.

There's a lot we still don't know about long COVID, the symptoms that linger for weeks or months after the initial infection clears up. Sometimes, symptoms seem to continue indefinitely, significantly impacting a person’s quality of life.

Also known as "long-haul COVID" or "post-acute COVID," long COVID can show up as one or more of a multitude of symptoms. In addition to many others, ongoing symptoms can include:

• Fatigue
• Changes in taste or smell
• Difficulty breathing
• Brain fog
• Cough
• Chest pain
• Joint pain
• Heart palpitations
• Worsening symptoms after physical activity

We don't yet know how often long COVID occurs after a delta infection, or among vaccinated people. One February study found that roughly 30% of people were still experiencing symptoms between three and nine months after having COVID.

About one in 12 participants reported that symptoms affected their ability to complete at least one "activity of daily living," with household chores being the most common.

Long COVID is a developing issue that will continue to affect millions of people for the foreseeable future. Standardized treatment options may not be available yet, but clues to diagnosis could lie in — of all places — the eyes.

Corneal nerve fibers in a healthy person (A), a COVID-19 patient without long COVID (B) and one with long COVID (C). [Image courtesy: British Journal of Ophthalmology]

There may be a connection between long COVID and damage to microscopic nerve fibers in the cornea, the clear layer in front of the pupil, according to a study published in July.

Ophthalmologists used a painless, noninvasive test called a corneal confocal microscopy, a procedure used to diagnose several other conditions that affect the cornea.

While the study acknowledged that more research is needed, the discovery could eventually be a stepping stone toward recovery for people affected by ongoing symptoms, especially neurological.

COVID-19's symptoms can be unpredictable, and, like other illnesses, it's important not to self-diagnose. People who experience symptoms are advised to follow the latest guidance from the CDC.

If you think that you or someone you know has COVID-19 or long-haul COVID, speak with a medical professional.

If you notice emergency symptoms such as difficulty breathing, chest pain or pressure, confusion or skin discoloration, seek medical attention as soon as possible.

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