Binocular disparity
Binocular disparity is the difference between the images from the left and right eyes. This difference can be caused by one or more of the following: horizontal disparity: a difference caused by the left and right eyes looking from slightly different directions, which can cause depth differences between objects to be perceived; vertical disparity, which is associated with vertical misalignments and tilting the head; and cyclodisparity which is associated with unequal rotations of the two eyes around their visual axes; aniseikonia: a significant difference in the size of the retinal images in the two eyes.