A sensory mechanism for amblyopia: psychophysical studies.

Psychophysical investigations of the effect of amblyopic process on the sustained and transient channels in the afferent visual pathway are reported. The experiments on photopic luminosity, increment-threshold spectral sensitivity, spatial contrast sensitivity, and reaction-time measures of suprathreshold grating detection provide converging evidence that in naturally occuring amblyopia of humans, the sustained neural channels are more severely affected than the transient channels. However, it appears that the sustained channels are not totally nonfunctional, but rather have a higher intensity requirement than normal.