Retinal hemodynamics and oxygen metabolism: potent inflammatory indicators for thyroid eye disease.

BACKGROUND: To determine whether retinal vascular function parameters can serve as quantitative and sensitive indicators to distinguish active from inactive thyroid eye disease (TED). METHODS: Fifty two patients with TED (80 eyes) were recruited in our cohort study. Detection of retinal vascular functions included retinal hemodynamics (blood flow velocity, vessel diameter, blood flow) and oxygen metabolism (oxygen saturation, arteriovenous oxygen saturation difference, oxygen concentration, arteriovenous oxygen concentration difference, oxygen delivery, oxygen metabolism, oxygen extraction fraction). Linear mixed-effects models accounting for inter-eye correlation were used to compare active and inactive TED. Discriminative performance was evaluated using receiver Operating Characteristic analysis. RESULTS: Active TED exhibited significantly higher arterial oxygen saturation (β = 4.74, 95% CI: 1.20–8.28, p = 0.010), venous oxygen saturation (β = 6.83, 95% CI: 2.53–11.12, p = 0.002), arterial oxygen content (β = 0.89, 95% CI: 0.19–1.58, p = 0.014), venous oxygen content (β = 1.22, 95% CI: 0.43–2.01, p = 0.003), and oxygen delivery (β = 1.19, 95% CI: 0.07–2.31, p = 0.038) compared to inactive TED. No significant differences were observed in retinal hemodynamic parameters. Among these individual parameters, DO2 and CO2A demonstrated the highest discriminative efficacy for assessing inflammatory activity in TED, with an AUC of 0.761 and 0.758, respectively. A multivariate model incorporating age, sex, smoking status, and CO2A achieved an AUC of 0.833 (95% CI: 0.711–0.955), with favorable calibration and robustness confirmed by bootstrap validation. CONCLUSIONS: Alterations in retinal vascular functional parameters between active and inactive TED were more substantial than structural changes. This study demonstrates for the first time significant alterations in retinal oxygen metabolism in active TED, characterized by elevated oxygen saturation, content, and delivery. These findings suggest retinal oxygen metabolism is strongly associated with disease activity and represents a promising quantitative marker for disease monitoring.