Alterations in Corpus Callosum Subregion Microstructure Associated With Visual Dysfunction in Individuals With Cerebral Visual Impairment.

BACKGROUND: Cerebral/cortical visual impairment (CVI) is among the leading causes of visual impairment in children. Yet, identifying the neural correlates of CVI remains challenging due to the heterogeneous underlying etiologies and visual manifestations. While previous work has focused on intra-hemispheric white matter connections, in this cross-sectional observational study, we focus on the potential contribution of inter-hemispheric white matter connections via the corpus callosum (CC) to the severity of visual dysfunction in individuals with CVI. METHODS: Seven segments of the CC were isolated in 21 participants with CVI (10 M, 11 F, mean age: 20.19 years, 8.38 s.d., range: 10-44 years) and 26 controls (10 M, 16 F, mean age: 19.00 years, 5.82 s.d., range: 10-28 years) without a history of brain injury or visual impairment. Mixed models were used to investigate within- and between-group differences in diffusion metrics. Associations between diffusion metrics of the CC segments and severity of visual dysfunctions across five domains determined by the CVI Questionnaire were calculated in an exploratory analysis within the CVI group. RESULTS: Significantly lower fractional anisotropy (FA) and higher radial diffusivity (RD) measures were observed for isthmus and splenium, as well as higher mean diffusivity (MD) for the splenium in the CVI group compared with control following correction for multiple comparisons. In our exploratory analysis, the severity of impairments in object and face processing, impairments moving in space, and anxiety-related behaviors were significantly negatively associated with diffusion properties of posterior midbody CC segments in the CVI group. Additional positive correlations between visual disinterest and AD of the rostrum were also observed. CONCLUSIONS: Our results demonstrate that while CVI is associated with atypical diffusion properties in the posterior portions of the CC, the severity of visual dysfunctions may be associated with underlying tissue composition of the anterior and mid-posterior segments of the CC.