THE VALUE OF FLASH VISUAL-EVOKED POTENTIALS IN ALBINISM

In albinism, the majority of temporal retinal fibers serving the nasal visual field cross at the chiasm and project to the contralateral hem isphere. This misrouting is seen in hemispheric asymmetries present in the visual evoked potential (VEP). Misrouting of retinal fibers was a lso thought to occur in dissociated vertical deviation, Prader-Willi s yndrome, and perhaps carrier states of albinism. However, recent liter ature is reaching the conclusion we have drawn in our laboratory: only albinism shows VEP hemispheric asymmetries that reverse when the othe r eye is stimulated. Use of different stimuli, recording conditions, a nd response criteria among investigators has created some confusion in differentiating what constitutes asymmetry. We conclude that use of a diffuse flash stimulus and a bipolar electrode derivation that compar es differences between the left and right occipital hemispheres will c learly differentiate albinism from all other conditions, making it esp ecially useful in a pediatric population.