Stretching Red Blood Cells with Optical Tweezers

In this work we report on experiments to measure the deformability of red blood cells (RBCs) when subject to stretching with optical tweezers. Individual red blood cells are trapped directly in a dual optical tweezers, and subject to a stretching protocol that is the same for all cells under test. Differences in the resulting extension are therefore indicative of differences in cell deformability. The targets for investigation are RBCs taken from patients with type 2 diabetes mellitus (T2DM) who exhibit diabetic retinopathy (DR), and from patients with birdshot chorioretinopathy (BCR). We find a statistically significant change in deformability for RBCs from DR patients compared to a control group, but no significant change for BCR patients. These results offer support to the importance of the role of RBC biomechanical properties in the progress of these conditions.