Months pass, and studies on Covid-19 allow us to know a little more every day about the impact of the virus on our general state of health.
Researchers from the University of Michigan looked into collateral damage that was poorly documented : vascular occlusions of the retina. As proof, 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 ocular pathologies, potentially serious and irreversible, which occurred after contamination with Covid.
Increase in retinal vascular occlusions
The first pathology seen is a central retinal artery occlusion (ROAC) which can cause sudden blurring or loss of vision in one eye. The authors of the study observed a 29.9% increase in this vascular accident over the period of two to 26 weeks after contamination with Covid-19 compared to this same period before diagnosis.
These figures 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 this same period, varying between two and 26 weeks compared to the same duration without coronavirus contamination.
Potentially serious strokes
These retinal strokes are usually caused by blood clots or fatty deposits that 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 complete loss of vision in the eye.
Retinal vein occlusion, on the other hand, is associated with diabetes or high blood pressure. But it is also linked to other eye disorders such as glaucoma (damage to the optic nerve).
While many patients with these “eye strokes” regain some level of vision, there is currently no treatment to regain 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 occlusions suggests that Covid-19 affects veins more seriously than arteries. A conclusion that could improve the therapeutic management of this type of accident.
An unknown origin
Nevertheless, the study has a limit: it does not address the cases of retinal vascular occlusions in patients admitted to intensive care who, given their deteriorated state of health, could not declare these sudden changes in vision.
Another study conducted by researchers from the Fondation Adolphe de Rothschild Hospital had previously observed the presence of nodules in the macula (area of the retina located at the back of the eye), which can be a sign of inflammation or direct eye damage. As for the previously mentioned pathologies, the origin of these nodules is still unexplained.
But one of the hypotheses put forward is that the virus directly infects the eye by entering the cells via the ACE2 receptora protein necessary for the entry of the virus into the body.