Sensitivity deficits consistent with aberrant crossed visual pathways in human albinos.

There is both anatomical and electrophysiological evidence that human albinos have abnormally crossed visual pathways. The present study examined some perceptual consequences of such pathways on the visual abilities of 12 oculocutaneous albinos and one ocular albino. Measurements were made of visual fields in all subjects. For seven subjects, contrast sensitivity functions were obtained for the central, nasal, and temporal retinas. There was a wide variation in the dimensions of the visual fields, but there was no evidence for a loss corresponding to the origin of the aberrant projections. On the basis of their contrast sensitivity functions, however, it was possible to classify the albinos into two groups. One group, with higher overall sensitivity, showed no differences between central, nasal, and temporal retina. The other group showed a marked depression in sensitivity for the temporal retina, indicating that in some albinos, information from the retinal region corresponding to the aberrant pathway is degraded.