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Lee-Anne Khuu, John G Flanagan, Faryan Tayyari, Shaun Singer, Michael Brent, David Huang, Ou Tan, Christopher Hudson, Retina Research Group; Retinal Blood Flow is Reduced in Patients with Non-Proliferative Diabetic Retinopathy. Invest. Ophthalmol. Vis. Sci. 2014;55(13):4342.
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To assess total retinal blood flow (TRBF), retinal vascular reactivity (VR) and glycosylated hemoglobin (A1c) in patients with Type 2 diabetes and non-proliferative diabetic retinopathy (NPDR).
6 controls (3 Males (M), 70 ± 5 yrs) and 5 patients with type 2 diabetes and NPDR (2M, 67 ± 8 yrs, 12.2 yrs known duration) were recruited. Images were acquired to assess TRBF using the RTVueTM Fourier-Domain Optical Coherence Tomographer (FD-OCT) using the double circular scan protocol. Retinal VR was assessed using an inhaled isocapnic hyperoxic stimulus and images were acquired using the Canon Laser Blood Flowmeter (CLBF) to measure retinal arteriolar diameter, blood velocity, max-to-min velocity ratio (a parameter reflecting vascular compliance) and derived RBF. Retinal VR was quantified as the difference in a given hemodynamic parameter between an individual’s homeostatic baseline and the isocapnic hyperoxic stage. Forearm blood was collected to determine glycosylated hemoglobin (A1c) values. Retinal VR for each hemodynamic parameter and A1c values were compared between groups using Mann Whitney U. Any associations between retinal hemodynamic parameters and A1c were investigated using Spearman R test.
In the NPDR group, the mean TRBF was significantly lower compared to the control group (34.6 ± 10.4 vs. 49.7 ± 5.4 ul/min, respectively, p=0.014). There were no significant differences found between groups for VR for arteriolar diameter, blood velocity and flow using the CLBF (p>0.0315). VR max-to-min velocity ratio tended to be lower in the NPDR group compared to healthy controls but was not statistically significant (-0.04 ± 0.73 vs. 2.78 ± 5.2, p=0.082). Mean A1c was significantly negatively associated with TRBF across the two groups (r=-0.85, p=0.006). VR max-to-min velocity ratio non-significantly increased with increasing TRBF across groups (r=0.61, p=0.077).
Using Doppler FD-OCT, our preliminarily results show that TRBF was significantly lower in patients with NPDR group when compared to controls. The data also suggests that high glycosylated A1c values are related to a reduction in TRBF.
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