Any of the alternating slabs of cells perpendicular to the surface of the primary visual cortex (Area V1), approximately half a millimetre wide and extending through all six cortical layers, appearing after special staining procedures as orderly stripes, with all the cells in a slab responding mainly to inputs from the same eye, and in layer 4C, which receives inputs directly from the lateral geniculate nuclei, responding only to inputs from the dominant eye for that particular slab. The anatomical basis of this alternation is that each axon from the lateral geniculate nucleus, after ascending through the deep layers of the cortex, terminates in layer 4C in two or three half-millimetre wide clusters of synaptic endings, such clusters being separated by half-millimetre gaps that are occupied by clusters of synaptic endings of axons from the other eye, resulting in an orderly alternation of left and right dominance columns. Also called an eye-dominance column. See also ocular dominance. Compare orientation column.