Red blood cell membrane mechanical fluctuations in non-proliferative and proliferate diabetic retinopathy

Purpose: To study whether cell membrane mechanical fluctuation (CMF) of red blood cells (RBCs) are attenuated in non-proliferative diabetic retinopathy (NPDR) and proliferative diabetic retinopathy (PDR). Patients and methods: Point dark-field microscopy-based recordings of local membrane displacements (frequency 0.3-25 Hz) were compared between type 2 diabetes patients with mild-to-moderate and severe NPDR and type 2 diabetes patients with PDR. The matched control group, corresponding to each stage of diabetic retinopathy, was based on non-diabetic patients who were evaluated in our clinic due to cataract. Results: The average mean values of the maximal CMF amplitude did not differ between RBCs of NPDR patients (n=20) and controls (n=20) (19.5±1.5% and 19.6±1.7%, respectively). A statistically significant decrease in CMF amplitudes was observed in patients with PDR compared with patients with a non-proliferative disease (NPDR -20%, PDR -90%). Conclusion: This new rheological characteristic demonstrates differences in the mechanical properties of RBCs in different stages of diabetic retinopathy. The significant reduction in CMF in patients with PDR may shed more light on the possible mechanism modulating retinal ischemia and leading to angiogenesis in these patients. Larger-scale studies are needed to evaluate these findings and the possible correlation between significantly lower CMF values and the progression of diabetic retinopathy.