[Ambulatory autonomy and visual motion perception in a case of almost total cortical blindness]

A 37-year-old man experienced cortical blindness following a bilateral stroke in the territory of the posterior cerebral arteries. Four years later, the measurement of visual field defects (Goldmann perimeter) showed persistence of bilateral blindness with a 2-degree preservation of macular vision and a perifoveal sparing between 10 to 30 degrees of eccentricity in the left inferior quadrant. Despite this visual impairment, the subject was able to perform visually-guided locomotion. Moreover he consciously perceived visual motion in the blind parts of his visual field. CT and MRI showed a lesion involving most of the striated cortex. The visual cortex located in the internal occipito-parital regions was relatively spared. The contribution of this structure to extra-striated vision of motion is discussed.