Altered white matter in early visual pathways of humans with amblyopia

• Successful identification of human visual pathways using probabilistic tractography.
• Differences in early pathways found between amblyopes and age-matched controls.
• Thalamo-cortical pathways differed in mean diffusivity, but not fractional anisotropy.
• No significant differences found in cortico-cortical pathways of amblyopes and controls.
• Amblyopia may alter the white matter properties of early visual pathways.

Amblyopia is a visual disorder caused by poorly coordinated binocular input during development. Little is known about the impact of amblyopia on the white matter within the visual system. We studied the properties of six major visual white-matter pathways in a group of adults with amblyopia (n = 10) and matched controls (n = 10) using diffusion weighted imaging (DWI) and fiber tractography. While we did not find significant differences in diffusion properties in cortico-cortical pathways, patients with amblyopia exhibited increased mean diffusivity in thalamo-cortical visual pathways. These findings suggest that amblyopia may systematically alter the white matter properties of early visual pathways.