COVID-19 may increase risk for rare eye clots

Patients with COVID-19 may have an increased risk of rare vision-threatening blood clots in the eye for months afterward, new findings suggest.

Because SARS-CoV-2 infections increase the risk of blood vessel obstructions at other sites in the body, researchers studied nearly half a million COVID-19 patients to see whether they would develop clots in the veins or arteries of the retina, the nerve tissue at the back of the eye that receives images and sends them to the brain. Over the next six months, 65 patients had a retinal vein occlusion. While that number is low, it reflects a statistically significant 54% increase compared with pre-COVID infection rates, according to a report published on Thursday in JAMA Ophthalmology. Retinal artery clots were 35% more common after COVID-19 than before, but that difference might have been due to chance. The clots most often occurred in patients with other conditions that increased their risk of blood vessel problems, such as diabetes, high blood pressure, and high cholesterol.

Clot risk did not appear to be associated with the severity of the coronavirus infection. The study cannot prove that COVID-19 caused the clots in these patients’ eyes, the researchers noted, saying larger studies of the issue are needed.