COVID can seriously damage your vision, even if you didn’t have symptoms, new study says. Experts say to watch for these signs

If you’ve had COVID-19, you may want to have your eyes checked. SARS-CoV-2, the coronavirus that causes the disease, can infect the inside of your eyes, according to research published in April in the journal PLOS Pathogens. This holds true even if the virus didn’t enter your body through the surface of your eyes.

Pawan Kumar Singh, PhD, an assistant professor of ophthalmology at the University of Missouri School of Medicine, led a team of researchers who found that inhaled viruses can reach highly protected organs such as the eyes, potentially causing long-term damage. SARS-CoV-2 does so by breaching the blood-retinal barrier, layers of cells that shield the retina, the part of your eye that senses light, from microbial pathogens.

“Earlier, researchers were primarily focused on the ocular surface exposure of the virus,” Singh said in a news release. “However, our findings reveal that SARS-CoV-2 not only reaches the eye during systemic infection but induces a hyperinflammatory response in the retina and causes cell death in the blood-retinal barrier. The longer viral remnants remain in the eye, the risk of damage to the retina and visual function increases.”

Using a humanized mice model, Singh and his team showed that the prolonged presence of SARS-CoV-2 spike proteins can cause problems such as:

• Retinal artery and vein occlusion: An “eye stroke” that happens when a retinal blood vessel is blocked

• Retinal microaneurysm: The swelling and leaking of tiny blood vessels called capillaries in the back of the eye, often seen in people with diabetes

• Vascular leakage: Leaky blood vessels in the eyes

“For those who have been diagnosed with COVID-19, we recommend you ask your ophthalmologist to check for signs of pathological changes to the retina,” Singh said. “Even those who were asymptomatic could suffer from damage in the eyes over time because of COVID-19 associated complications.”

What are symptoms of retinal disease?

The following symptoms may indicate retinal disease, according to the National Eye Institute:

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• Blindness

• Blurry or wavy vision

• “Curtain” or shadow over your field of vision

• Dull color vision

• Flashes of light in one or both eyes

• Floating spots in your vision

• Loss of central vision

• Sudden increase in floaters

• Sudden vision loss

If you don’t have an ophthalmologist, your primary care physician can refer you to one and help determine the best course of treatment.

Though the blood-retinal barrier of people with compromised immune systems is known to be susceptible to bacteria and viruses, MU claims Singh’s study is the first to suggest SARS-CoV-2 can infect that of otherwise healthy people. That said, immunocompromised people and those with diabetes or high blood pressure may face more severe COVID-related eye health issues if left untreated.

“Now that we know the risk of COVID-19 to the retina, our goal is to better understand the cellular and molecular mechanisms of how this virus breaches the blood-retinal barrier and associated pathological consequences in hopes of informing development of therapies to prevent and treat COVID-19-induced eye complications before a patient’s vision is compromised,” Singh said.

For more on COVID-19: 

This story was originally featured on Fortune.com