News — CHICAGO – February 18, 2025 – How much can the eyes reveal about a person? A first-of-its-kind study from and published in the is giving experts an idea how long COVID affects the body by looking through the eyes. The research could help doctors diagnose and track how the condition impacts people over time and provide insight into the cause of long COVID.
In the study, researchers used advanced imaging techniques to examine the retinas of non-hospitalized long COVID patients from the Northwestern Medicine Neuro COVID-19 Clinic and found that patients with long COVID experienced a significant reduction in the density of blood vessels in the back of the eye, compared to healthy individuals.
“This finding bridges gaps between ophthalmology, neurology, and COVID-19, helping us better understand how inflammation affects different organs in the body,” said senior author of the study and ophthalmology lead of the . “The change in blood vessels in the deep part of the retina supports the hypothesis that long COVID affects similar blood vessels in other parts of the body, like the brain, which can potentially contribute to the symptoms of long COVID such as memory loss, brain fog and fatigue.”
In patients with long COVID, researchers found that the most significant change was a decrease in blood flow in the smallest blood vessels in the deeper layers of the retina. Researchers believe this decrease in circulation may be reflective of decreased blood circulation in the brain, which may lead to neurologic symptoms.
“In oculomics – the field of study that examines the relationship between eye health and systemic diseases – we are understanding the power of the retina as a biomarker for disease, identifying early signs of diabetes, cardiovascular disease, and neurodegenerative disorders. It’s exciting to see how long COVID could fit into this framework,” said Dr. Gill. “Retinal imaging allows us to see the blood vessels that we cannot readily image elsewhere, so in this context, the eyes really are the ‘window to the soul.’”
Building on these findings, researchers are launching a longitudinal study that will examine how the changes in the deep retinal blood vessels relate to patient symptoms and other established markers of long COVID. They hope to determine if retinal imaging could be used as a tool to diagnose, manage and predict the progression of long COVID over time, as well as identify its cause.
“Even though the immediate threat of the COVID-19 pandemic has decreased, approximately one-third of COVID-19 survivors experience lingering effects. This issue affects an estimated 17 million adults in the U.S. and comes with significant healthcare and economic burdens, costing about $600 million in lost wages,” said , chief of neuroinfectious diseases and global neurology at Northwestern Medicine, who oversees the Neuro COVID-19 Clinic and is the co-director of the Northwestern Medicine Comprehensive COVID-19 Center. “There are currently no specific treatments for long COVID, and this research helps to advance our understanding of the condition. By studying the effects of COVID-19 on the body, we can improve diagnosis, management, and support for those affected.”
To date, the Neuro COVID-19 Clinic has cared for nearly 3,000 long-haulers from 44 states. For more information, visit and to schedule an appointment, please call 312.695.7950.
Available for interviews:
- Manjo K. Gill, MD, ophthalmologist at Northwestern Medicine and ophthalmology lead of the Northwestern Medicine Comprehensive COVID-19 Center
- Igor Koralnik, MD, (CORRAL-nick), co-director of the Northwestern Medicine Comprehensive COVID-19 Center
RSS