title: Changes in angle of optic nerve and angle of ocular orbit with increasing age in Japanese children.
abstract: OBJECTIVE
  To study changes in the opening angle of the optic nerve and the angle of the ocular orbit with increasing age in normal Japanese children.
  
  
  METHODS
  We studied 147 normal children (aged 6 months to 18 years) who had undergone CT as a diagnostic procedure. Measurements were performed on axial CT images that included the entire optic nerve of both eyes. The opening angle of the optic nerve was defined as the angle formed by the intersection of a line running through the left optic nerve and a vertical line passing through the centre of the nose. The opening angle of the orbit was defined as the angle formed by the intersection of a line running tangentially along the deep lateral wall of the left orbit and a vertical line passing through the centre of the nose. The relationship between age and these opening angles was analysed by regression analysis.
  
  
  RESULTS
  The correlation between age and opening angle of the optic nerve was not significant. In contrast, the opening angle of the orbit decreased relatively rapidly until about 2-3 years of age, and then it stabilised. The decrease in the opening angle of the orbit with increasing age was significant (p<0.001). The relationship between these two parameters was best fitted by a logarithmic regression curve.
  
  
  CONCLUSIONS
  Because the opening angle of the orbit decreased significantly with increasing age, this factor must be considered when diagnosing and treating strabismus in children.
authors.affiliation: Department of Ophthalmology, Mie University Graduate School of Medicine, Tsu, Japan.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Tsukitome
authors.affiliation: Department of Ophthalmology, Osaka Medical Center and Research Institute for Maternal and Child Health, Osaka, Japan.
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Hatsukawa
authors.affiliation: Department of Ophthalmology, Osaka Medical Center and Research Institute for Maternal and Child Health, Osaka, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Morimitsu
authors.affiliation: Yagasaki Eye Clinic, Ichinomiya, Japan.
authors.forename: Teiji
authors.initials: T
authors.lastname: Yagasaki
authors.affiliation: Department of Ophthalmology, Mie University Graduate School of Medicine, Tsu, Japan.
authors.forename: Mineo
authors.initials: M
authors.lastname: Kondo
mesh_terms: D000293:Adolescent; D000375:Aging / Q000502:physiology*; D044466:Asian People; D002648:Child; D002675:Child, Preschool; D006801:Humans; D007223:Infant; D007564:Japan; D009900:Optic Nerve / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D009915:Orbit / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed
keywords: Anatomy; Optic Nerve; Orbit