(A) Using DTIStudio tractography software and a population-specific template, major fiber tracts connecting the occipital cortex to the rest of the brain such as the inferior fronto-occipital fibers, inferior longitudinal fasciculus, occipito-callosal, and geniculostriate fibers, as well as chiasm tracts, were extracted bilaterally. Subsequent to extractions, fiber bundles were superimposed on the color fractional anisotropy template image. The template image is shown in radiological convention (right brain side is shown on the left). Following Dougherty et al. (20), the occipito-callosal fibers were extracted by placing three regions of interest in the upper, middle, and lower areas of the inferior portion of the splenium to extract tracts that ended in dorsal V3 visual areas (blue), dorsal and ventral V1 and V2 areas (yellow), and ventral V3 and V4 areas (red). In addition to vision-related tracts, bilateral corticospinal tracts were extracted as nonvision control fibers. Tractography analyses of all of these tracts showed no difference between the LCA2 patients and sighted controls except for the geniculostriate fibers. As shown in Table 4, the averaged fractional anisotropy along the right geniculostriate fibers for the LCA2 patients did not differ from the control group (P = 0.389). However, tractography results showed significantly decreased fractional anisotropy along the left geniculostriate fibers (P = 0.0045). (B) Laterality indices (R-L) for the average fractional anisotropy along the left and right geniculostriate fibers for LCA2 patients and sighted controls were evaluated. The laterality index used was: (right geniculostriate average fractional anisotropy − left geniculostriate average fractional anisotropy)/(right geniculostriate average fractional anisotropy + left geniculostriate average fractional anisotropy). LCA2 patients showed much higher average fractional anisotropy values for the right geniculostriate fibers, and their laterality index (red bar) significantly (P < 0.04) differed from matched sighted controls (blue bar).