Purpose
Haemorheological disturbances observed in diabetics have been postulated to play a role in the pathogenesis of diabetic microangiopathy. The present study was conducted to investigate the role of red blood cell (RBC) deformability and factors affecting RBC deformability in patients with diabetic retinopathy (DR) using modified optical tweezers method.
Methods
A pilot project was conducted as per declaration of tenets of Helsinki with ethics board approval (14/WM/1038). Bloods from age matched control and patients was collected for standard biochemical and hematological tests and for RBC deformability index (DI) assessment using Optical tweezers. A dual optical tweezers (two trapping beams) was made by splitting and recombining a single laser beam. RBCs were trapped directly (i.e. without microbead handles) in the dual optical tweezers where they adopt a "side-on" image.
Results
Blood from 8 healthy controls with mean age of 52.37yrs and 4 diabetic patients with mean age of 52.00yrs was analysed. Unstretched RBC length for control group was 6.847μm (±0.29, 95CI: 6.83-6.86) and 7.001 μm (±0.27, 95CI: 6.97-7.02) for diabetic RBCs (p<0.0001). Maximal stretched length for RBCs using two laser beams of optical tweezers was 7.362μm (±0.24, 95CI: 7.35-7.37) for control group and 7.401μm (± 0.262, 95CI: 7.37-7.42) for diabetic group (p=0.0021). DI was calculated by subtracting unstretched length of RBCs from maximal stretched length of RBCs. The DI for control group was 0.57 (±0.22, 95CI: 0.55-0.59) and that for diabetic RBCs was 0.39 (±0.26, 95CI: 0.37-0.42) (p<0.0001). With DI as dependent variable, we did bivariate analysis for age (yrs), hemoglobin, hematocrit, red blood cell count, mean corpuscular volume, red blood cell distribution width, platelet concentration, mean platelet volume, erythrocyte sedimentation rate, serum creatinine, total proteins, C-reactive protein, random blood glucose, HbA1C, total cholesterol and fibrinogen. None of the factors were found to be significantly correlated with DI on bivariate analysis.
Conclusions
DI of RBC from DR was significantly lower in comparison with normal healthy controls. None of the biochemical and hematological factors in the blood were found to affect DI for RBCs.