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The Delta variant and your eyes: What we know

  • As of August 19, 2021, the Delta variant had been detected in 148 countries worldwide. 

  • As of late July, nearly all COVID-19 cases in the United States were caused by a new strain of the virus known as the Delta variant.

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

  • Vaccines are less effective against Delta, 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 current spike in COVID infections could be the second-worst — or worst — upturn since the start of the pandemic. It comes at the hands of the Delta variant, which spreads as easily as chickenpox among people who are unprotected.

The Alpha, Beta, Gamma and Delta are four variants of concern. Delta cases were first documented in India in October 2020 before being spotted in the U.K and U.S. in February 2021. The Delta variant expanded, becoming the dominant variant worldwide. Globally, 148 countries had cases of the Delta variant by August 19. Of those, Delta accounted for over half of all COVID-19 cases in approximately 45 countries and over 80% of cases in 37 countries.  

In fact, the breakthrough infections of the virus recently recorded in India have been predominantly that of the Delta and Alpha variants. “So far, for all the breakthrough infections that have been sequenced, there has been no other variant identified but for the Delta, and, in some cases, we know that we have Alpha in the country,” said the Department of Biotechnology (DPT) secretary Renu Swarup as reported by ANI.

The CDC estimates more than 97% of new COVID cases in America are currently caused by Delta infections, as of August 7. About 83% of total cases are caused by the original Delta variant, while 14% are caused by a handful of subtypes known as Delta Plus

In India, the second wave of the coronavirus was caused by the Delta variant, which was discovered to be more dangerous than the original strain. This was one of the most challenging times for the Indian healthcare system. Though the number of cases has finally decreased in India, there is a risk of a third wave. This also increases the possibility of the spread of a new mutation, Delta Plus, which has been discovered in some Indian states.

Delta Plus is a concerning variant, as it carries mutations from both the Beta variant and the Delta variant. In Maharashtra, the Delta Plus variant count has crossed 100, with 27 new cases recorded as of 24 August 2021.

As per a Times of India report, the Delta Plus variant spreads 60 per cent faster than the Delta variant. The three states where most cases of Delta Plus have been discovered are Maharashtra, Kerala and Madhya Pradesh. Though there are concerns about Delta Plus due to its ability to spread quickly, it is not rising at a faster pace. However, it remains a concerning variant. 

The two most widely available COVID-19 vaccines in India — Covidsheild and Covaxin — will still protect you against the Delta variant. A study published by the Indian Council of Medical Research (ICMR) recently revealed that Bharat Biotech's Covaxin is effective against Delta Plus. A similar study by ICMR and National Institute of Virology (NIV), Pune, on Covisheild revealed that Covid-19-recovered individuals with both doses of Covishield have higher immunity against the Delta variant.

Can the Delta variant cause eye symptoms?

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.

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

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 seasonal allergies.

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.

MIS-C: A rare but growing concern in children

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-Cmultisystem 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

According to the Ministry of Health and Family Welfare (MoHFW), as more children test positive for COVID, they also seem to develop MIS-C, a post-COVID complication. As per the MoHFW, MIS-C is rare but a very serious condition. It affects the age group of those between five and 18.

As of July 25, doctors reported over 400 cases of MIS-C in Bangaluru, suggesting parents get their children tested for COVID-19 without any delay. “Symptoms of MIS-C show up two to four weeks after Covid-19 infection. In some cases, the symptoms may occur after six weeks. MIS-C is the result of an immune storm: antibodies are produced in large numbers, so much so that they start affecting the heart, liver and kidneys,” said Dr Sanjay KS, the director of the Indira Gandhi Institute of Child Health to Times of India.

While rare, it is recommended that you seek emergency care if you notice symptoms such as difficulty breathing, chest pain or pressure, pale skin or any other severe symptoms.

The eyes could offer insight into long COVID cases

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. Hindustan Times reports that nearly 15-20 per cent of hospitalised COVID-19 patients are returning and complaining about some of the other complications they are facing. However, these numbers may be higher, as some people experiencing long COVID symptoms like body ache, among others, might not be returning, states Dr. Vivek Nangia, head of the department of respiratory medicine at Max Hospital, Saket.

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. Standardised 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.

Getting help from a medical professional

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 World Health Organization (WHO), National Centre for Disease Control, MoFHW and 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 discolouration, seek medical attention as soon as possible.

READ NEXT: Can COVID-19 vaccines cause eye-related side effects?

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