In vivo observations of red blood cell deformations while traversing the individual retinal capillaries in the human eye becomes reality thanks to recent work published by Phillip Bedggood, Yifu Ding, and Andrew Metha. The authors report the application of a high-speed (300-400 fps) flood-illuminated adaptive optics (AO) system to acquire noninvasive video data of single-file cellular flow in the retinal capillary network. Custom AO system operating at 20 Hz allowed correction of the root-mean-square (RMS) wavefront error down to ∼0.06 μm or better at 835 nm over a 7.0 mm pupil, ensuring lateral resolution of 1.5–2 μm. A new analysis approach was developed to render the average shape of red blood cells within capillary tubes of varying size, permitting quantification of cell shape and orientation. As reported by the authors, diverse cellular geometries were observed across lumens ranging from 3.2 to 8.4 μm in diameter. As capillaries narrowed, red blood cells transitioned from rounder to more elongated shapes, from being counter-aligned to aligned with the flow axis. Remarkably, the red blood cells maintained an oblique orientation relative to the flow axis in many vessels. In the future, it may be possible to use these measurements of cell geometry to infer shear stress, a primary driver of endothelial damage in vascular disease.

---

---

 Add Comment

You must log in to add comments.