title: Assessment of red blood cell deformability in type 2 diabetes mellitus and diabetic retinopathy by dual optical tweezers stretching technique.
abstract: A pilot cross sectional study was conducted to investigate the role of red blood cells (RBC) deformability in type 2 diabetes mellitus (T2DM) without and with diabetic retinopathy (DR) using a dual optical tweezers stretching technique. A dual optical tweezers was made by splitting and recombining a single Nd:YAG laser beam. RBCs were trapped directly (i.e., without microbead handles) in the dual optical tweezers where they were observed to adopt a "side-on" orientation. RBC initial and final lengths after stretching were measured by digital video microscopy, and a Deformability index (DI) calculated. Blood from 8 healthy controls, 5 T2DM and 7 DR patients with respective mean age of 52.4 yrs, 51.6 yrs and 52 yrs was analysed. Initial average length of RBCs for control group was 8.45 ± 0.25 μm, 8.68 ± 0.49 μm for DM RBCs and 8.82 ± 0.32 μm for DR RBCs (p < 0.001). The DI for control group was 0.0698 ± 0.0224, and that for DM RBCs was 0.0645 ± 0.03 and 0.0635 ± 0.028 (p < 0.001) for DR group. DI was inversely related to basal length of RBCs (p =  .02). DI of RBC from DM and DR patients was significantly lower in comparison with normal healthy controls. A dual optical tweezers method can hence be reliably used to assess RBC deformability.
authors.affiliation: Moorfields Eye Hospital NHS Foundation Trust, London, UK.|Department of Mechanical Engineering, University College London, London, UK.|Institute of Ophthalmology, University College London, London, UK.|National Healthcare Group Eye Institute, Tan Tock Seng Hospital, Singapore.
authors.forename: Rupesh
authors.initials: R
authors.lastname: Agrawal
authors.affiliation: Department of Physics and Astronomy, University College London, London, UK.
authors.forename: Thomas
authors.initials: T
authors.lastname: Smart
authors.affiliation: Moorfields Eye Hospital NHS Foundation Trust, London, UK.
authors.forename: João
authors.initials: J
authors.lastname: Nobre-Cardoso
authors.affiliation: Department of Physics and Astronomy, University College London, London, UK.
authors.forename: Christopher
authors.initials: C
authors.lastname: Richards
authors.affiliation: Department of Mechanical Engineering, University College London, London, UK.
authors.forename: Rhythm
authors.initials: R
authors.lastname: Bhatnagar
authors.affiliation: Moorfields Eye Hospital NHS Foundation Trust, London, UK.
authors.forename: Adnan
authors.initials: A
authors.lastname: Tufail
authors.affiliation: Institute of Ophthalmology, University College London, London, UK.
authors.forename: David
authors.initials: D
authors.lastname: Shima
authors.affiliation: Department of Physics and Astronomy, University College London, London, UK.
authors.forename: Phil
authors.initials: P
authors.lastname: H Jones
authors.affiliation: Moorfields Eye Hospital NHS Foundation Trust, London, UK.|Institute of Ophthalmology, University College London, London, UK.
authors.forename: Carlos
authors.initials: C
authors.lastname: Pavesio
mesh_terms: D048430:Cell Shape / Q000502:physiology; D003430:Cross-Sectional Studies; D003924:Diabetes Mellitus, Type 2 / Q000503:physiopathology*; D003930:Diabetic Retinopathy / Q000503:physiopathology*; D004907:Erythrocyte Deformability / Q000502:physiology*; D004912:Erythrocytes / Q000166:cytology; D005260:Female; D006405:Hematology / Q000295:instrumentation / Q000379:methods; D006801:Humans; D008297:Male; D018715:Microscopy, Video; D008875:Middle Aged; D052898:Optical Tweezers; D010865:Pilot Projects; D012044:Regression Analysis