The Glenn A. Fry Award Lecture

This paper reviews psychophysical evidence that the visual performance and, by inference, the underlying neural losses of strabismic and anisometropic amblyopes are fundamentally different. The data of amblyopes are considered in the light of recent models for normal spatial vision. It is argued that the spatial deficits which are found in anisometropic amblyopes can be understood largely in terms of reduced resolution and contrast sensitivity, as would be expected on the basis of early experience with a defocused image in one eye. In contrast, the spatial deficits found in strabismic amblyopes are more profound than can be predicted on the basis of either resolution, or contrast sensitivity, and may have their basis in a coarse cortical spatial sampling grain.