title: Three-dimensional optical coherence tomography evaluation of vascular changes at arteriovenous crossings.
abstract: OBJECTIVE
  To study the three-dimensional morphologic features of retinal arteriovenous crossings with optical coherence tomography (OCT) and elucidate the vascular changes associated with crossing phenomena as seen on fundus photographs.
  
  
  METHODS
  We examined 150 consecutive eyes with no ocular disease. In each eye, fundus photographs were taken, and one randomly selected arteriovenous crossing was examined by OCT. The OCT analysis was performed by using sequential thin sections along and perpendicular to the retinal vessels.
  
  
  RESULTS
  The OCT analysis of these arteriovenous crossings showed that the veins abruptly changed their directions to pass the artery and frequently displayed focal luminal narrowing with no compression or flattening. The OCT measurements revealed that the veins narrowed by 21.0% ± 12.9% at the crossings. The degree of narrowing correlated positively with the diameter of the crossing arteries (r = 0.419, P < 0.001). On fundus photographs, crossing phenomena were observed in 103 of the 150 selected crossings. Venous narrowing measured by OCT was more severe in eyes with crossing phenomena on fundus photographs (P < 0.001). Four types of crossing phenomena were observed: concealment, tapering, deflection, and humping. Venous narrowing rates were similar among all four types. Although the subjects with deflection or humping phenomena were more likely to suffer from hypertension, the mean venous narrowing rate at such crossings was similar to that observed with the other crossing phenomena.
  
  
  CONCLUSIONS
  Arteriovenous crossings exhibited focal narrowing of the venous lumen with no compression or flattening. Increased venous narrowing and larger arteries were observed at crossings with crossing phenomena.
authors.affiliation: Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan.
authors.forename: Kyoko
authors.initials: K
authors.lastname: Kumagai
authors.forename: Akitaka
authors.initials: A
authors.lastname: Tsujikawa
authors.forename: Yuki
authors.initials: Y
authors.lastname: Muraoka
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Akagi-Kurashige
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Murakami
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Miyamoto
authors.forename: Ryo
authors.initials: R
authors.lastname: Yamada
authors.forename: Nagahisa
authors.initials: N
authors.lastname: Yoshimura
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012016:Reference Values; D012160:Retina / Q000166:cytology; D012161:Retinal Artery / Q000033:anatomy & histology*; D012169:Retinal Vein / Q000033:anatomy & histology*; D041623:Tomography, Optical Coherence / Q000379:methods*
keywords: crossing phenomenon; hypertension; venous narrowing