posted on 18/10/2020 07:00 / updated on 18/10/2020 07:29
At the beginning of the covid-19 pandemic, experts believed that the new disease, like other respiratory illnesses, mainly attacked the lungs. Over time, Sars-CoV-2 infection has been found to cause damage to other organs, such as the heart, kidneys and even the brain. In recent analyzes, researchers found evidence of effects also in the eyes. They detected the presence of coronavirus RNA and some eye changes in infected people. The investigations are preliminary, but, according to experts, also essential to guide new scientific work that will help to unravel the impacts of the infectious agent on the vision.
Researchers know that some respiratory viral diseases can cause a common eye problem: conjunctivitis. So there was no surprise when people with covid-19 and inflammation
eyes. However, little was known about the influence of the new coronavirus on vision, which led to more accurate analyzes. “Ophthalmic involvement in patients with this disease has so far been limited to conjunctivitis. There are no reports on the existence of Sars-CoV-2 in intraocular tissue. This motivated us to analyze the eye tissues of people who died as a result of the covid ”, says, in a statement, Maria Casagrande, a researcher in the Department of Ophthalmology at the University of Hamburg-Heppendorf (UKE), in Germany.
Casagrande and his team analyzed the eyes of 14 people and detected the infectious agent’s RNA in three. “In this study, we provided, for the first time, evidence for the detection of Sars-CoV-2 RNA in the human retina. In previous analyzes, the presence of the virus in ocular tissues only occurred in the conjunctiva (mucous membrane that surrounds the white part of the eye) and in tears ”, say the authors of the work, published in the specialized magazine Ocular immunology and Inflamation.
The researchers believe that the presence of the virus is justified by the existence, in the ocular system, of ACE2, a protein used by the pathogen to enter the organism. “The presence of the viral entry receptor in the retina of humans and also of animals, such as pigs and rodents, is something known in the medical field and was one of the reasons for our initial distrust”, they explain.
The team believes that the data obtained needs to be deepened and opens the door to research that can help understand the behavior of Sars-CoV-2 in the eye system. “Due to the respiratory and cardiac risks of this disease, most research focuses on these two areas, but we believe that studies in other systems should not be ignored”, highlight the authors. “Our study is still a pilot, a starting point for further analysis, not least because we cannot yet say that the virus replicates in the retina and in which retinal structures it is in,” says Casagrande.
A second study by US scientists also found evidence of the virus’s RNA in the eye system. In this case, the analysis was done on material obtained from organ donors. The scientists analyzed the cornea of 33 people and detected coronavirus RNA in those who tested positive for the infection. The pathogen was in the cornea and in the vitreous mood.
“As far as we know, our study is the first to show the presence of the virus in the cornea. But we still have questions to answer. We do not know how it got to the eye and we do not know whether it replicates there, ”explain the authors in the article, led by Shahzad I Mian, from the University of Michigan. Scientists stress that more accurate analysis needs to be done to clarify the doubts that have arisen. “New tests on patients who have died and also in vitro studies may help us to better understand the behavior of the virus in the cornea and other eye regions”, they consider. The results obtained so far are in an article published in the journal MedRxiv.
A systemic disease
“The first documented manifestations of the Sars-CoV-2 virus were respiratory, but when this disease appeared in China, an ophthalmologist noticed several cases of conjunctivitis. This caught his attention, which defined the increase in cases of the eye problem as a cause of an unknown disease. These data, which emerge after months of pandemic and show the presence of the virus in the eye and the possibility of more serious conditions of previous diseases, such as glaucoma, are examples of the content we are learning in this long path of clinical manifestations of covid-19. We see data every day that reinforce how systemic this disease is. It causes damage in different areas, and the eyes are more of a region that can be affected. It is important to keep following and writing this chapter. This will help us to further open up the range of factors used to diagnose this disease and to understand how it presents clinically, which will help us during its fight. ”
David Urbaez, scientific director of the Federal District Infectious Disease Society