Wallraven et al. (2026)
- Authors: Timon Wallraven, Roman Günthner, Isabelle Lethen, Andrea Ribeiro, Maciej Lech, Frederike Cosima Oertel, Lukas G. Rees, Bernhard Haller, Lukas Streese, Henner Hanssen, Maximilian Wunderle, Christoph Schmaderer
- Institutes: Technical University of Munich (TUM), Munich, Germany, Charité-Universitätsmedizin Berlin, Berlin, Germany, Max Delbrück Center for Molecular Medicine, Berlin, Germany, University of Basel, Basel, Switzerland
- Publisher: medRxiv (Preprint)
- Link: DOI
Summary
This research identifies a visible, objective marker for the “invisible” symptoms of Long COVID and ME/CFS by demonstrating that the tiny blood vessels in the eye are both structurally and functionally impaired. By linking this damage directly to inflammation and symptom severity, the study provides a vital diagnostic tool that could help patients gain clinical recognition and guide the development of targeted therapies. The findings suggest that the severity of blood vessel dysfunction mirrors the severity of the disease, offering a measurable way to track the illness.
What was researched?
This study investigated structural and functional changes in the retinal microvasculature of patients with Post-COVID Syndrome (PCS) and ME/CFS. Researchers used Retinal Vessel Analysis (RVA) to determine if these changes could serve as non-invasive markers of systemic endothelial dysfunction.
Why was it researched?
Persistent cardiovascular risks and vascular symptoms are common in post-viral conditions, but they are often difficult to quantify with standard clinical tools. There is an urgent need for accessible, objective methods to assess microvascular health and understand the biological basis of symptoms like brain fog and fatigue.
How was it researched?
This prospective, observational study involved 102 PCS patients, 62 ME/CFS patients, and various control groups including healthy, never-infected, and recovered individuals. The team performed Retinal Vessel Analysis to measure vessel diameters and the ability of blood vessels to dilate in response to light stimulation, while also analyzing circulating inflammatory markers like IL-6.
What has been found?
PCS and ME/CFS patients showed significant microvascular impairment, including narrower retinal arterioles and a reduced ability for vessels to dilate, with the most severe damage observed in the ME/CFS group. These vascular changes correlated strongly with symptom severity—particularly neurocognitive issues—and were linked to elevated inflammatory markers and iron dysregulation. A combined vascular model was able to distinguish ME/CFS patients with high accuracy.
Discussion
The findings suggest a dose-response relationship between microvascular injury and disease burden, indicating that post-viral syndromes involve a systemic inflammatory-endothelial axis. While the study is currently a preprint, the results highlight a biologically coherent vascular phenotype that distinguishes these patients from healthy or recovered controls.
Conclusion & Future Work
Retinal Vessel Analysis provides a promising, non-invasive “window” into the microvascular health of patients with PCS and ME/CFS. Future research may utilize these retinal markers to track disease progression and evaluate the effectiveness of new treatments targeting endothelial function.