Increased red cell rigidity might affect retinal capillary blood flow velocity and oxygen transport efficiency in...

Retinal capillary blood flow velocity, oxygen transport efficiency (TE) and rheological properties of the blood were measured from twenty-two type II diabetes patients and nineteen normal subjects. The results showed that diabetic patients had increased plasma viscosity (P < 0.01). Also, for both shear rates of 225 sec-1 and 450 sec-1, they had increased blood viscosity (P < 0.002, both), red cell rigidity (Tk) (P < 0.002 and P < 0.001, respectively), but lower values of TE (P < 0.001, both), and of retinal capillary blood flow velocity (P < 0.005). Furthermore, TE was linearly correlated with Tk for both shear rates of all subjects (r = -0.80, gamma = 225 sec-1, P < 0.001; r = -0.84, gamma = 450 sec-1, P < 0.001). The impaired rheological properties of blood and red cell rigidity might result in both reduced capillary blood flow velocity and lower values of TE, which then possibly contribute to the deterioration of retinopathy or microangiopathy in diabetic patients.