Preserved visual evoked potential in infancy cortical blindness: Relationship to blindsight

Abstract

Sixteen infants with diagnosed cortical blindness from a variety of causes were assessed with the visual evoked potential (VEP). Twelve of 13 cases with eventual visual recovery had measurable though abnormal VEP's provided these were performed within one month of diagnosis. Only one of the three patients whose blindness persisted for the three year follow-up period had a VEP response. The dissociation of the VEP and behaviorally manifest vision is puzzling. We found a surprising lack of primate experimental and human anatomical studies to explain our findings. Nevertheless the VEP did anticipate visual recovery in most of our infants. The value of the VEP here differs from the results of other reports in older children and adults.

Key Words:

• cortical blindness
• visual evoked potential
• blindsight
• extrageniculate pathway