Optic nerve (ON) straightness represented as path length relative to shortest geometric distance to the globe-ON junction in central gaze, and small and large angle horizontal ductions to the average angles indicated in each column. In all groups, the ON was significantly straighter in adduction than in the other gaze positions, and its straightness in adduction did not differ significantly among groups or with duction angle (P>0.15). However, in central gaze and abduction, the ON was significantly more redundant in OAG-low than in OAG-high or the control group. For all groups, the ON was highly significantly straighter in adduction than in central gaze (P<0.0002). SEM – standard error of mean.