As doctors learn more about COVID-19 infection, they are finding that in rare cases, it appears tied to a disturbing eye condition.
Retinal vein occlusion is a blockage of the small veins that carry blood away from the retina, which causes blurred vision. It usually occurs in people suffering from diabetes, atherosclerosis, high blood pressure, or eye conditions such as glaucoma, macular edema or vitreous hemorrhage.
And COVID-19 might just trigger retinal vein occlusion in people with these maladies, researchers suggest.
"There have been many case reports looking at vascular damage to the retina following COVID-19 infection," said lead researcher Dr. Bobeck Modjtahedi, an eye surgeon at Southern California Permanente Medical Group in Pasadena.
"Anecdotally, many doctors have also observed these events. However, the true risk of retinal vascular occlusions after COVID-19 infection has remained poorly understood," he said.
Although uncommon after COVID-19, researchers found an increase in the incidence of retinal vein occlusions, but not retinal artery occlusions, in the six months after COVID when compared with the six months before infection, Modjtahedi said.
"This may be because of delays in diagnosis because patients may take some time before seeking eye care after vision changes or could indicate that the condition endures after the acute infectious stage," he said.
These vein occlusions could also be due to worsening blood pressure control or reduced physical activity during the COVID recovery period, Modjtahedi said.
"COVID-19 can have significant effects throughout the body, the effects of which can last for months or longer," he said.
"Retina vascular occlusions can result in permanent vision loss and can require long-term treatment, so it is important to understand that there may be an association between COVID-19 and retina vein occlusions," Modjtahedi added. "Patients with visual changes or ophthalmic symptoms following COVID-19 infection should be evaluated expeditiously."
For the study, Modjtahedi's team collected data on nearly 433,000 men and women diagnosed with COVID-19. Sixty-five of them developed retinal vein occlusion, the researchers found.
Modjtahedi's group also looked at the incidence of retinal artery occlusion, which is similar to retinal vein occlusion except it affects the arteries that carry blood to the retina.
They found that cases of retinal artery occlusion were even rarer, with 16 patients diagnosed with the condition. The majority of these cases, too, developed in the months after COVID-19.
Dr. Talia Kaden, an ophthalmologist at the Manhattan, Eye, Ear and Throat Hospital in New York City, said COVID-19 might cause retinal vein occlusion but this study doesn't prove that.
COVID-19 might trigger the condition in patients who were already at risk for retinal vein occlusion, she said.
"Basically, these were people on the tipping point, and they got COVID and that swung them over," said Kaden, who wasn't involved in the study.
'It's also possible that while they had COVID, they let their blood pressure spike or weren't moving around as much, which also were risk factors," she said.
Kaden said that people who suffer from diabetes, high blood pressure and high cholesterol should already be seeing a doctor and an ophthalmologist for a checkup at least once a year.
Retinal vein occlusion shouldn't be ignored. The condition can cause the retina to swell or develop abnormal blood vessels, Kaden said.
Some people will have no symptoms or only mild symptoms, but sometimes retinal vein occlusion can cause significant loss of vision, she said.
"If they don't have a doctor, they should get one," Kaden said. "If they started to notice any blurriness, even if it's not central blurriness, just in the top of their vision or the bottom of their vision, that's something that they should see an eye doctor about."
The report was published online April 14 in the journal JAMA Ophthalmology.
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SOURCES: Bobeck Modjtahedi, MD, eye surgeon, Southern California Permanente Medical Group, Pasadena; Talia Kaden, MD, ophthalmologist, Manhattan, Eye, Ear and Throat Hospital, New York City; JAMA Ophthalmology, April 14, 2022, online