All Segments Considered

    • Pathway that conducts visual information from the eyes to vision-associated cerebral cortex
    • Three segments: optical, retinocortical, and perceptual
    • Optical Segment: focuses light on the retina using the refractive powers of the cornea and lens
    • Retinocortical Segment: transduces light into neural signals that travel through the retina, optic nerve, optic chiasm, optic tracts, lateral geniculate bodies, and optic radiations to primary visual cortex
    • Perceptual Segment: the dorsal perceptual stream carries the signal to parietal vision-associated cerebral cortex for visuospatial and attentional vision; the ventral perceptual stream carries the signal to temporal vision-associated cerebral cortex to allow recognition of viewed material
    • Optical segment: uncorrected refractive errors and media opacities or irregularities produce unclear vision (but never scotomas!)
    • Retinocortical segment: lesions anywhere from the retina to the visual cortex produce visual field defects whose shape often allows localization of the lesion within this segment
    • Perceptual segment: lesions of the occipito-parietal stream produce deficits in visuospatial and attentional function; lesions of the occipito-temporal stream produce deficits in visual recognition