ABSTRACT
The optics of the eye is good enough, but there may or may not be a retinal deficiency. For at least one type of amblyopia there exist good reasons to believe that the retina is essentially normal. This is the type of dysfunction that is the most enigmatical and that leads us directly to the problem of local sign. The concept of the deformed or scrambled visual field raises problems of philosophy, theoretical psychology and physiology. Many theories of the topognostic faculty have been proposed. The theory of the eidola is vividly described by Lucretius in De Rerum Natura. A local sign theory can be viable, however, when the labels are in the activity of the wires. The chapter shows how the correlation structure in optic nerve activity patterns can be considered in geometrical terms, that is how such patterns can be considered to be isomorphic to configurations in a “visual field”.
