Monocular components of the fixation disparity curve.

Experiments were conducted to characterize the distribution of the monocular components of fixation disparity, i.e., ascertain whether or not the fixation disparity measured by nonius alignments is equally divided between the two eyes or has an unequal distribution. Computer generated nonius lines were used to measure the monocular components of the forced vergence fixation disparity curve (FDC) for subjects with normal binocularity. Thirty-three percent of all subjects tested showed unequal distribution of their monocular components. The composite FDC's for subjects with unequal distribution of the monocular components tended to have steeper slopes than those with equally distributed components. It was concluded that equally divided monocular components are not a prerequisite for good binocularity.