As the coronavirus pandemic evolves and spreads worldwide, more information emerges on how the virus affects the body. What was once a respiratory illness has now become a systemic infection, affecting multiple organs.
Now, a new study published in the journal EClinicalMedicine shows that the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes the coronavirus disease (COVID-19), targets the retina.
A team of researchers at the Eye Clinic, Luigi Sacco Hospital, ASST Fatebenefratelli-Sacco, and the Department of Infectious Diseases in Italy aimed to determine if the COVID-19 disease affects the retina since the disease has been liked to microvascular alterations.
The researchers analyzed the retina of COVID-19 patients within 30 days from the start of the symptoms.
Alterations of the retina
To arrive at the study findings, the team screened the fundus of patients with COVID-19 to detect alterations of the retina and its vasculature to explore potential correlations with clinical parameters.
The researchers conducted a cross-sectional and monocentric study at the Luigi Sacco Hospital, Department of Biomedical and Clinical Science in Milan, Italy, one of the countries heavily impacted by COVID-19.
The participants of the study included patients who were admitted to the infectious diseases department of the hospital, and who tested positive for SARS-CoV-2 infection. The team excluded patients admitted to the intensive care unit and those with retinal disorders, including diabetic retinopathy.
Study participants completed questionnaires describing their ocular symptoms. They also underwent pupil dilation of both eyes using mydriatic drops about 15 minutes before the researchers captured retinal images.
Study findings
Overall, 54 patients and 133 unexposed participants were included in the study. The findings show that people with COVID-19 had retinal findings of hemorrhages, cotton wool spots, dilated veins, and tortuous vessels.
Further, after the team measured the mean arteries diameter (MAD) and mean veins diameter (MVD) among the participants, they found that both the MAD and MVD were higher in patients with COVID-19 than unexposed participants.
"We found that both retinal arteries and veins were larger compared to unexposed subjects. Besides, veins diameter was larger in more severe cases and showed an inverse correlation with time to symptoms onset," the researchers wrote in the paper.
"COVID-19 can affect the retina. Retinal veins' diameter seems directly correlated with the disease severity. Its assessment could have possible applications in the management of COVID-19," they added.
The research findings provide a better understanding of how SARS-CoV-2 could target many parts of the body, aside from the lungs. In the past, people with underlying medical conditions are at a high risk of getting sick with COVID-19, and they are more likely to die from complications.
As the pandemic grew, the virus has shown to affect not only the lungs but also the heart, brain, and other vital organs. Previous studies have reported a link between COVID-19 and the eyes. Now, this study provides a deeper understanding of the virus's wrath, affecting the retina, vital for vision.
COVID-19 cases around the world
The coronavirus disease is actively spreading in many countries across the globe. The United States is still the nation with the highest number of infections, with more than 6.88 million cases. Overall, the global case toll has now ballooned to a staggering 31.44 million cases, with the death toll surpassing 967,000.
Many countries report a surging number of cases, particularly those that have reopened most of their businesses and schools. India and Brazil follow the U.S. in terms of the number of cases, with more than 5.56 million and 4.55 million cases, respectively.
Limited impact of prenatal COVID-19 exposure on child neurodevelopmental outcomes