Retinal vascular reactivity and kidney function in type 2 NPDR

Abstract

Abstract Purpose To investigate the association between retinal vascular function and kidney function in non‐proliferative diabetic retinopathy (NPDR). Methods 10 control subjects (mean age 55±12yrs), 22 type 2 patients with mild‐to‐moderate NPDR (61±9yrs) and 14 type 2 patients with moderate‐to‐severe (62±11yrs) NPDR were recruited. Retinal vessel diameter, velocity, velocity pulse amplitude and blood flow were assessed in the supero‐temporal arteriole using bi‐directional laser Doppler flowmetry and simultaneous vessel reflectometry. Retinal vascular reactivity (VR) was quantified as the difference in hemodynamic parameters between baseline and isocapnic hyperoxia. Forearm blood samples were taken to derive plasma sodium, creatinine, albumin, glomerular filtration rate (GFR) and hemoglobin (A1c) levels. Urine samples were taken to derive albumin:creatinine ratio (A:C ratio) and microalbumin. All parameters were compared between groups and VR was correlated with systemic markers. Results VR for vessel diameter, velocity, pulse amplitude and blood flow were not different between groups. A:C ratio (ANOVA, p=0.010), microalbumin (p=0.005) and A1c (p=0.006) were elevated in patients with diabetes. The magnitude of VR for retinal vessel diameter was weakly correlated with GFR across the pooled groups (r=‐0.3992, p=0.006). Within the moderate‐to‐severe NPDR group, VR for vessel diameter was strongly correlated with GFR (r=‐0.8551, p=0.001). VR for pulse amplitude was also found to be moderately related to plasma Na levels in moderate‐to‐severe NPDR group (r=‐0.6809, p=0.007). Conclusion Disturbance of retinal VR was related to kidney function in patients with NPDR, especially in the moderate‐to‐severe group.