Residual visual function after loss of both cerebral hemispheres in infancy.

PURPOSE: To investigate whether and what kind of visual function is still present in the absence of both cerebral hemispheres.

METHODS

Binocular visual function of five children who had suffered the loss of both cerebral hemispheres and the visual fields of 30 controls 5 to 12 months of age were examined according to a perimetric method based on forced-choice, preferential-looking methods.

RESULTS

Results show that after the destruction of both cerebral hemispheres, a stimulus presented binocularly beyond 5 degrees eccentricity did not elicit a response. However, two children were still able to fixate steadily and to follow a stimulus presented binocularly within the central 5 degrees , with eye and head movements despite the absence of both cerebral hemispheres. One child responded only to a moving face or a moving drum with black and white stripes presented binocularly within the central 5 degrees but not to a moving spot of light. The binocular visual field of 30 controls 5 to 12 months of age almost reached the dimensions of the adult binocular visual field.

CONCLUSIONS

Neural structures in the midbrain, including the superior colliculi and the pretectum, seem to be able to mediate visual function in the foveal and macular regions. These structures are, however, unable to mediate the presence of a functional visual field beyond 5 degrees eccentricity.