title: Factors associated with optic nerve head blood flow and color tone: a retrospective observational study.
abstract: OBJECTIVE
  To investigate the relationship between optic nerve head (ONH) blood flow and color tone.
  
  
  METHODS
  Retrospective observational study conducted between February 2014 and August 2014. We examined 29 eyes of 17 young healthy subjects and 37 eyes of 26 cataract patients undergoing cataract surgery. Blood flow was measured using laser speckle flowgraphy, and color tone was quantified using the public domain ImageJ software. Blood flow and color tone of the ONH before and after cataract surgery were compared. The influence of age, axial length, and color tone on ONH blood flow were also investigated.
  
  
  RESULTS
  Mean blur rate (MBR) in the ONH decreased with increasing age (R = -0.437, P < 0.001) and axial length (R = -0.306, P = 0.012). In young subjects, ONH redness had a moderate positive correlation with MBR (R = 0.376, P = 0.044); however, this correlation was not observed in the study population as a whole (R = 0.066, P = 0.601). MBR in the ONH was higher after cataract surgery (P < 0.001). Moreover, the ONH redness reduced postoperatively from that preoperatively (P < 0.001). An increase in MBR after cataract surgery correlated with improved visual acuity (R = -0.399, P = 0.014) and decreased redness the of ONH (R = -0.433, P < 0.01).
  
  
  CONCLUSIONS
  Ocular blood flow decreased in older people and in myopic eyes. The reddish appearance of the ONH was not an indicator of a circulatory condition, particularly in older people. Lens opacity appeared to underestimate hemodynamic quantification using laser speckle flowgraphy.
authors.affiliation: Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Sakyo-ku, Kyoto, 606-8507, Japan.
authors.forename: Yoshimasa
authors.initials: Y
authors.lastname: Kuroda
authors.affiliation: Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Sakyo-ku, Kyoto, 606-8507, Japan. akihito1@kuhp.kyoto-u.ac.jp.
authors.forename: Akihito
authors.initials: A
authors.lastname: Uji
authors.affiliation: Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Sakyo-ku, Kyoto, 606-8507, Japan.
authors.forename: Nagahisa
authors.initials: N
authors.lastname: Yoshimura
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D058452:Axial Length, Eye / Q000503:physiopathology; D001783:Blood Flow Velocity / Q000502:physiology; D002386:Cataract / Q000503:physiopathology*; D002387:Cataract Extraction; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D017078:Laser-Doppler Flowmetry; D008297:Male; D008875:Middle Aged; D009898:Optic Disk / Q000098:blood supply*; D012039:Regional Blood Flow / Q000502:physiology*; D012171:Retinal Vessels / Q000502:physiology*; D012189:Retrospective Studies
keywords: Cataract; Laser speckle flowgraphy; Ocular blood flow; Optic nerve head color