Circulating blood glutathione levels influence retinal microvascular function in healthy individuals

Purpose To assess the relationship between retinal vessel reactivity and oxidative stress markers in the systemic circulation. Methods Two hundred and twenty four healthy volunteers (aged 20-70 years) free of cardiovascular risk factors based on medical history, lipid profiles, blood pressure, and body mass index were included in this study. Measurements included plasma cholesterol, blood glucose, triglycerides, oxidized (GSSG) and reduced (GSH) forms of glutathione. Arterial and venous retinal vessel reactivity was assessed using the dynamic retinal vessel analyser (DVA, IMEDOS, Germany) according to an already established protocol. Results A simple correlation model showed that arterial and venous dilation amplitude was inversely with correlated with age (r= -0.4041, p= 0.0001; r= -.4045, p= 0.0001, respectively). Forward step-wise multiple linear regression analysis revealed that independent of age and other systemic influences, blood GSH levels were positively correlated with arterial and venous percent dilation (β= 0.158, p= 0.0133; β= 0.224, p= 0.0004, respectively), and overall dilation amplitude (β= 0.245, p = 0.0003; β= 0.230, p= 0.0006, respectively). In addition, blood GSH levels negatively influenced the arterial constriction response slope (SlopeAC: β= -1.722, p= 0.0024), while GSH and overall redox status (GSH/GSSG) influenced percent constriction in both the artery (β= -0.345, p=0.0002, β= -0.229, p= 0.0462, respectively) and vein (β= -0.253, p= 0.0001; β= -0.156, p= 0.0177, respectively). Conclusion In otherwise healthy individuals, retinal microvascular function is influenced by systemic anti-oxidative capacity.