Unveiling the Th17/Treg Imbalance: a New Lens on Macular Perfusion in Thyroid-Associated Ophthalmopathy.

BACKGROUND: The aim of this study was to investigate the association between Th17/Treg imbalance and macular blood flow abnormalities in patients with thyroid-associated ophthalmopathy (TAO). METHODS: A prospective cohort study was designed to include 71 patients with TAO and 50 healthy controls. Macular blood flow measurements were quantified by optical coherence tomography angiography, including foveal vessel density (FVD) and foveal perfusion density (FPD) in 1 mm from the central fovea, macular vessel density (MVD) and macular perfusion density (MPD) in 6 mm from the central fovea, and macular foveal avascular zone (FAZ) was also measured. Peripheral blood Th17/Treg ratio was measured by flow cytometry and its association with blood flow measurements was assessed by multiple linear regression modeling, correcting for confounding factors such as age and gender. RESULTS: MVD (16.38 ± 2.83 vs. 18.91 ± 2.20, p < 0.001) and MPD (44.5% vs. 48.1%, p < 0.001) in the TAO group were significantly lower than those of the control group. Th17/Treg ratio showed a significant positive correlation with MPD (multifactorial β = 0.01, p = 0.002) and negatively correlated with FAZ (multifactorial β = -0.36, p = 0.018). No significant correlations were found for other indicators (FVD, FPD, and MVD) and confounders (TAO activity, gender, and age). CONCLUSIONS: Th17/Treg imbalance is directly involved in microcirculatory disorders in TAO by decreasing MPD and enlarging macular FAZ, suggesting that immunomodulation may be a therapeutic target to improve macular blood flow abnormalities in TAO patients.