title: Adaptive optics-assisted identification of preferential erythrocyte aggregate pathways in the human retinal microvasculature.
abstract: OBJECTIVE
  To characterize human parafoveal blood flow using adaptive optics scanning laser ophthalmoscopy (AO-SLO).
  
  
  METHODS
  In 5 normal subjects, erythrocyte aggregate distributions were analyzed on 3 different days. Erythrocyte aggregates were described as a "dark tail" in AO-SLO. The characteristics of the pathways with dark tail flow in the parafovea were measured. Additionally, the tendency for dark tail flow before and after bifurcations was analyzed to study the blood flow in detail.
  
  
  RESULTS
  Average velocity in parent vessels with dark tail flow was 1.30±0.27 mm/s. Average velocity in daughter vessels with dark tail flow was 1.12±0.25 mm/s, and the average velocity of plasma gaps in daughter vessels without dark tail flow was 0.64±0.11 mm/s. Downstream from the bifurcations, the velocity in vessels with dark tail flow was higher than that in those without it (p<0.001), and the branching angles of vessels with dark tail flow were smaller than those of vessels without it (p<0.001).
  
  
  CONCLUSIONS
  Images from the AO-SLO noninvasively revealed pathways with and without dark tail flow in the human parafovea. Pathways with dark tail flow in the daughter vessels generally had faster flow and smaller bifurcation angles than daughter vessels without dark tail flow. Thus, AO-SLO is an instructive tool for analyzing retinal microcirculatory hemodynamics.
authors.affiliation: Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan.
authors.forename: Shigeta
authors.initials: S
authors.lastname: Arichika
authors.affiliation: Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan.
authors.forename: Akihito
authors.initials: A
authors.lastname: Uji
authors.affiliation: Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan.
authors.forename: Sotaro
authors.initials: S
authors.lastname: Ooto
authors.affiliation: Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan.
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Miyamoto
authors.affiliation: Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan.
authors.forename: Nagahisa
authors.initials: N
authors.lastname: Yoshimura
mesh_terms: D001783:Blood Flow Velocity; D004903:Erythrocyte Aggregation; D006801:Humans; D008833:Microcirculation; D055806:Microvessels; D009887:Ophthalmoscopy / Q000379:methods; D055095:Optics and Photonics; D012171:Retinal Vessels / Q000502:physiology