Months go by and studies on Covid-19 let us know a little more about the impact of the virus on our general health every day.
Researchers at the University of Michigan have looked at a little-documented collateral damage: retinal vascular occlusion. As evidence, today they are the first to establish a link between Covid-19 and this type of eye condition.
They were therefore able to observe an increase in both types of eye diseases, potentially serious and irreversible, occurring after contamination with Covid.
Increase in retinal vascular occlusions
The first pathology observed is central retinal artery occlusion (ROAC), which can result in sudden blurred vision or loss of vision in one eye. The study authors observed a 29.9% increase in this vascular accident over the period from two to 26 weeks after contracting Covid-19 compared to the same period before diagnosis.
These numbers are even more impressive for the second related pathology, retinal vein occlusion, which causes symptoms similar to OACR.
This time the increase is 47% over the same period and varies between two and 26 weeks compared to the same period without coronavirus contamination.
Potentially serious strokes
These retinal infarctions are usually caused by blood clots or fatty deposits blocking 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 complete loss of vision in the eye.
A retinal vein occlusion, on the other hand, is associated with diabetes or high blood pressure. However, it is also linked to other eye diseases such as glaucoma (damage to the optic nerve).
While many patients with these “eye punches” regain some level of vision, there is currently no treatment to restore full use of the affected eye (if it is completely blind).
According to the researchers, the very strong link between Covid-19 and retinal vein occlusion suggests that Covid-19 affects veins more than arteries. A conclusion that could improve the therapeutic management of this type of accident.
An unknown origin
However, the study has a limitation: it does not address the cases of retinal vascular occlusion in patients admitted to the ICU who, because of their deteriorating health, were unable to detect these sudden visual changes.
Another study conducted by researchers at the Adolphe de Rothschild Foundation Hospital had already observed the presence of nodules in the macula (area of the retina at the back of the eye), which can be a sign of inflammation or lesions of direct oculars. As with the previously mentioned pathologies, the origin of these nodules is still unclear.
However, one of the hypotheses put forward is that the virus infects the eye directly by entering cells via the ACE2 receptor, a protein necessary for the virus to enter the body.