occipital lobe seizure primary visual cortex seizure true Seizures in this area result in focal sensory visual seizures, these may be positive visual phenomena (typically multi-colored shapes such as circles, flashes), or negative phenomena such as loss of a part of a visual field or blindness (amaurosis). Bilateral loss of vision may occur and this may be in the form of a black-out or a white-out. More complex formed visual images, considered focal cognitive seizures, are not seen in seizures arising in this area. The visual phenomenon is seen in the contralateral visual field to the hemisphere of seizure onset.