title: Underdevelopment of optic radiation in children with amblyopia: a tractography study.
abstract: OBJECTIVE
  To detect the abnormalities of the optic radiation (OR) in children with amblyopia by diffusion tensor imaging (DTI) and tractography.
  
  
  METHODS
  Prospective, nonrandomized clinical trial.
  
  
  METHODS
  Fourteen children with amblyopia and 14 normally sighted children underwent DTI scanning. After the ORs were reconstructed by using tractography algorithm, voxels through which the anterior parts of ORs passed were determined for their values of fractional anisotropy (FA). The paired t test was applied to compare their mean FA values of right OR and left OR in the control group. For the amblyopia group, analysis of variance was conducted to determine the effect of laterality and vision status on the FA values. In addition, the voxel numbers of anterior and posterior parts of both ORs were calculated. The Student t test was used to compare the average FA of bilateral ORs and voxel numbers between the two groups.
  
  
  RESULTS
  Comparison demonstrated left-higher-than-right asymmetry in both amblyopic children and normal children. We found no significant difference of average FA between the amblyopic group (0.4832 +/- 0.0225) and control group (0.4770 +/- 0.0273). Voxel numbers of the anterior parts of both ORs were not significantly different between the two groups, whereas voxel numbers of their posterior parts in the controls were more than that of amblyopic children.
  
  
  CONCLUSIONS
  Tractography showed more voxels in the posterior ORs of normal children than in the amblyopic children, indicating that normal children have better development of the ORs. The underdevelopment of the ORs might reflect the dysfunction of visual cortex in children with amblyopia.
authors.affiliation: Department of Radiology, Peking University First Hospital, Beijing, China. ouyangxu2004@vip.sina.com <ouyangxu2004@vip.sina.com>
authors.forename: Sheng
authors.initials: S
authors.lastname: Xie
authors.forename: Gao Lang
authors.initials: GL
authors.lastname: Gong
authors.forename: Jiang X I
authors.initials: JX
authors.lastname: Xiao
authors.forename: Jin Tang
authors.initials: JT
authors.lastname: Ye
authors.forename: Hai Hua
authors.initials: HH
authors.lastname: Liu
authors.forename: Xiao Ling
authors.initials: XL
authors.lastname: Gan
authors.forename: Zi Tian
authors.initials: ZT
authors.lastname: Jiang
authors.forename: Xue Xiang
authors.initials: XX
authors.lastname: Jiang
mesh_terms: D000465:Algorithms; D000550:Amblyopia / Q000150:complications*; D001931:Brain Mapping; D002648:Child; D002675:Child, Preschool; D003941:Diagnostic Techniques, Ophthalmological; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D009901:Optic Nerve Diseases / Q000209:etiology*; D011446:Prospective Studies; D014793:Visual Cortex / Q000473:pathology*; D014795:Visual Pathways / Q000473:pathology*