title: Anteroposterior Tortuosity of the Retinal Vein at Arteriovenous Crossings in Healthy Subjects.
abstract: OBJECTIVE
  The purpose of this study was to investigate the effects of aging on anteroposterior tortuosity of the retinal vein at the arteriovenous (AV) crossing in healthy subjects.
  
  
  METHODS
  We examined 48 eyes of 24 healthy older Japanese subjects (>60 years), and, as controls, 42 eyes of 21 healthy younger Japanese subjects (<30 years). Retinal vein images at the AV crossing were obtained by optical coherence tomography. The depth of the vein was measured vertically from the outer border of the retinal pigment epithelium to the outer vein wall. We defined "m" as the deepest point of the vein at the AV crossing and "M" as the shallowest point. To evaluate the anteroposterior tortuosity of the retinal vein, we calculated the ratio m/M.
  
  
  RESULTS
  Mean m, M, and m/M in older subjects were 76.5 ± 13.1 µm, 142.7 ± 21.2 µm, and 0.52 ± 0.09, respectively. In younger control subjects, the values were 64.1 ± 12.6 µm, 139.9 ± 22.4 µm, and 0.46 ± 0.06. The values of "M" were not significantly different between groups, whereas both "m/M" and "m" were significantly (p = 0.021) lower in the older subjects than in the younger subjects.
  
  
  CONCLUSIONS
  Anteroposterior tortuosity of the retinal vein was evaluated based on the maximum and minimum retinal vein depth measurements at the AV crossing using optical coherence tomography. Anteroposterior tortuosity of the retinal vein at the AV crossing is increased with age.
authors.affiliation: a Department of Ophthalmology , Asahikawa Medical University , Asahikawa , Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Sogawa
authors.affiliation: a Department of Ophthalmology , Asahikawa Medical University , Asahikawa , Japan.
authors.forename: Taiji
authors.initials: T
authors.lastname: Nagaoka
authors.affiliation: a Department of Ophthalmology , Asahikawa Medical University , Asahikawa , Japan.
authors.forename: Tomofumi
authors.initials: T
authors.lastname: Tani
authors.affiliation: a Department of Ophthalmology , Asahikawa Medical University , Asahikawa , Japan.
authors.forename: Akitoshi
authors.initials: A
authors.lastname: Yoshida
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D058452:Axial Length, Eye; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D008875:Middle Aged; D012039:Regional Blood Flow / Q000502:physiology; D012161:Retinal Artery / Q000033:anatomy & histology* / Q000502:physiology; D012169:Retinal Vein / Q000033:anatomy & histology* / Q000502:physiology; D041623:Tomography, Optical Coherence; D055815:Young Adult
keywords: AV crossing; OCT; tortuosity