According to a study published Thursday by JAMA Ophthalmology which shed light on one of many little-understood long-term effects of the virus.
The first condition, called retinal artery occlusions, can cause sudden blurring or loss of vision in one eye, and was found to increase by 29.9% in the period of two to 26 weeks after the diagnosis of Covid-19 compared to the 26 to two-week period before diagnosis, the researchers concluded.
The second condition, retinal vein occlusions, causes similar symptoms to retinal artery occlusions and was even more strongly associated with Covid-19, with a 47% increase in the period two to 26 weeks after diagnosis. of Covid-19 compared to the period 26 to two weeks before diagnosis, according to the study.
The strong association between Covid-19 and retinal vein occlusions appears to confirm previous research suggesting that Covid-19 generally affects veins more severely than arteries, the researchers said – a finding that could help guide treatment approaches for patients. covid-19 patients.
Even after infection with Covid-19, retinal vascular occlusions remained rare, with retinal artery occlusions affecting approximately 1 in 333,333 patients and retinal vein occlusions affecting approximately 1 in 81,967 patients over the period from two to 26 weeks after their diagnosis.
The researchers did not find that hospitalized Covid-19 patients were more likely to experience retinal vascular occlusions than those who were not hospitalized.
The study included 432,515 patients with no history of retinal vascular occlusions more than six months prior to their diagnosis of Covid-19, and who were diagnosed with the virus between January 20, 2020 and May 31, 2021.
Retinal vascular occlusions occur when blood clots or fatty deposits block blood vessels in the retina, the part of the eye that receives light and transmits images to the brain. These occlusions can cause damage ranging from mild visual impairment to loss of vision in the entire eye. Retinal artery occlusion is linked to diabetes, high blood pressure, high levels of fat in the blood, and various disorders affecting the heart or carotid artery, according to the National Library of Medicine’s MedlinePlus service. Medical. Retinal vein occlusion is linked to diabetes, high blood pressure, fatty buildup in the arteries, and eye disorders like glaucoma. Results are variable: while many patients regain some degree of vision, there is no reliable treatment for whole-eye vision loss due to retinal vascular occlusion. These blockages can indicate the presence of clots or fatty deposits elsewhere in the body, warning of a risk of stroke, according to Johns Hopkins Medicine.
Although the immediate symptoms of Covid-19 have been well documented, scientists have struggled to understand the longer-term effects of the virus. A study published Monday by JAMA Neurology determined that the long-term loss of smell reported by some Covid-19 patients is linked to damage to the olfactory bulb, the part of the brain that processes smell. Covid-19 has also been linked to a range of vascular problems such as inflammation of the heart muscle or the sac containing the heart. Some researchers have concluded that much of the damage caused by the coronavirus is not directly inflicted by the virus itself, but by symptoms of infection such as inflammation, New York Times reports. The authors of the JAMA Ophthalmology One study has suggested a similar interpretation, theorizing that the initial vascular damage caused by Covid-19 infection may make some people more vulnerable to a pre-existing risk of retinal vascular occlusions.
It is possible that the JAMA Ophthalmology The study underestimated the risk of retinal vascular occlusions in critically ill patients because these patients’ conditions may have prevented them from notifying healthcare staff of vision changes, the researchers said.
What we don’t know
Further research would be needed to establish a causal relationship between Covid-19 infection and retinal vascular occlusions, researchers said. the JAMA Ophthalmology the study found only an association between the two conditions.
“Covid smell loss linked to brain damage, study finds” (Forbes)
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