Psychophysics of suppression.

In amblyopia the visual input from the amblyopic eye is suppressed. The difference in contrast sensitivity between the two eyes can lead to suppression of the amblyopic eye through dichoptic masking in anisometropic amblyopia and small angle strabismus. Binocular cells in the visual cortex may also be instrumental in bringing about suppression in small angle strabismus through fusional suppression and disparity-dependent suppression. In large angle strabismus without amblyopia suppression is very powerful and is probably a modified form of binocular rivalry suppression. Which particular mechanism is operating is dependent on the pathogenesis of the amblyopia, the depth of the amblyopia and, in strabismic amblyopia, the angle of strabismus. In any given subject more than one mechanism may be operating in the different areas of the field.