Adaptive Optics Scanning Laser Ophthalmoscopy was used to noninvasively acquire videos of single-file flow through live human retinal parafoveal capillaries. Videos were analyzed offline to investigate capillary flow dynamics. Certain capillaries accounted for a clear majority of leukocyte traffic (Leukocyte-Preferred-Paths, LPPs), while other capillaries primarily featured plasma gap flow (Plasma-Gap-Capillaries, PGCs). LPPs may serve as a protective mechanism to prevent inactivated leukocytes from entering exchange capillaries, and PGCs may serve as relief valves to minimize flow disruption due to the presence of a leukocyte in a neighboring LPP.
Keywords: (110.1080) Active or adaptive optics; (110.2960) Image analysis; (170.1470) Blood or tissue constituent monitoring; (170.4460) Ophthalmic optics and devices.