Tag: retinal imaging

Microvascular remodeling and endothelial dysfunction across the post-COVID-19 spectrum: a prospective observational case-control study

Abstract:

Background: Post-viral diseases, including post-COVID-19 syndrome (PCS) and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), cause substantial long-term morbidity. Persistent cardiovascular (CV) risk after acute infection highlights the need for accessible tools to quantify microvascular health.

Methods: The “All Eyes on PCS” is a prospective observational study assessing the microcirculation using retinal vessel analysis (RVA). Both dynamic and static parameters (DVA and SVA) were compared across never SARS-CoV-2 infected individuals (NI, n = 96), SARS-CoV-2 recovered individuals (n = 102), and PCS patients (n = 102), including a subgroup fulfilling ME/CFS criteria (n = 62). Analyses were complemented by propensity score-based weighting and multivariable adjustment. Associations with symptom severity and circulating biomarkers of endothelial dysfunction and inflammation were examined.

Results: PCS patients showed reduced venular flicker-induced dilation compared with recovered individuals (3.7% ± 2.2 vs. 4.8% ± 3.0, p = 0.006) and narrower retinal arterioles (CRAE) compared with both recovered (178.3 ± 15.5 μm vs. 186.1 ± 15.7 μm, p = 0.001) and NI individuals (184.4 ± 14.3 μm, p = 0.009). Arteriolar-to-venular ratio (AVR) was lower in PCS compared with NI (0.83 ± 0.06 vs. 0.87 ± 0.06, p < 0.001) and recovered participants (0.86 ± 0.07, p = 0.034). Findings remained largely consistent after age and sex balancing and adjustment for CV risk factors, although the association for AVR was attenuated. PCS patients fulfilling ME/CFS criteria showed the most pronounced retinal microvascular alterations, and a combined model discriminated ME/CFS patients with good accuracy (AUC = 0.79). Higher symptom burden was associated with lower AVR (r = – 0.21, p = 0.037), particularly for neurocognitive symptoms. IL-6, ICAM-1, and VCAM-1 were elevated in PCS and ME/CFS, and lower AVR was associated with inflammatory and iron-related markers (all adjusted p < 0.01).

Conclusions: PCS is associated with persistent endothelial dysfunction, most pronounced in ME/CFS patients and linked to symptom severity and ongoing inflammation. These findings support the potential use of RVA as a non-invasive tool for assessing and monitoring endothelial health in post-viral syndromes, with implications for cardiovascular risk stratification.

Trial registration: The All Eyes on PCS Study has previously been registered at ClinicalTrials.gov (NCT05635552).

Source: Wallraven T, Günthner R, Lethen I, Ribeiro A, Lech M, Oertel FC, Reeß LG, Haller B, Streese L, Hanssen H, Basta-Wunderle M, Schmaderer C. Microvascular remodeling and endothelial dysfunction across the post-COVID-19 spectrum: a prospective observational case-control study. BMC Med. 2026 Aug 19;24(1):456. doi: 10.1186/s12916-026-05144-9. PMID: 42625188. https://link.springer.com/article/10.1186/s12916-026-05144-9 (Full text)

Subclinical neurovascular and immune correlates of post-COVID-19 syndrome detected by retinal imaging

Abstract:

Background: Post-COVID-19 Syndrome (PCS) encompasses a range of persistent symptoms, including cognitive and autonomic disturbances, potentially linked to microvascular or neuroinflammatory mechanisms. Retinal imaging provides a non-invasive window into the central nervous system and vascular integrity. This study aimed to assess retinal structural and microvascular alterations in PCS patients and explore their relationship with symptom severity.

Methods: In this monocentric, cross-sectional, exploratory study, we performed Optical Coherence Tomography (OCT) and OCT Angiography (OCTA) in patients with PCS and a group of COVID-19 recovered individuals. Multiple circulating biomarkers reflecting endothelial dysfunction and chronic inflammation were measured. Associations with validated symptom scores (PCS Score, C19-YRS, PHQ-9, GAD-7) were evaluated.

Results: After adjusting for age and gender, no significant differences were observed in OCTA-derived vessel density (VD) or foveolar avascular zone (FAZ) between PCS patients and COVID-19-recovered controls. However, PCS patients exhibited significant thinning of the peripapillary retinal nerve fibre layer (pRNFL), ganglion cell inner plexiform layer (GCIP), and total macular volume (TMV). Lower values of these structural parameters were consistently observed in patients with higher symptom severity. Vascular parameters (VD and FAZ) were not related to clinical scores. Higher MCP-1 levels, a chemokine associated with chronic inflammation, were linked to lower inner nuclear layer and GCIP thickness.

Conclusion: Structural retinal alterations in PCS were associated with symptom burden and may reflect underlying neuroinflammatory or neurodegenerative processes. OCT parameters could serve as potential non-invasive biomarkers, warranting further investigation in longitudinal, multicenter studies.

Source: Wunderle M, Wicklein R, Ribeiro A, Carbajo-Lozoya J, Wöhnl A, Negele J, Kesseler V, Wild A, Niedermayer S, Lethen I, Lech M, Menten MJ, Kreitner L, Schmaderer C, Wallraven T. Subclinical neurovascular and immune correlates of post-COVID-19 syndrome detected by retinal imaging. Brain Behav Immun Health. 2026 Jul 25;56:101315. doi: 10.1016/j.bbih.2026.101315. PMID: 42571220; PMCID: PMC13451791. https://pmc.ncbi.nlm.nih.gov/articles/PMC13451791/ (Full text)