Vergence

A vergence is the simultaneous movement of both eyes in opposite directions to obtain or maintain single binocular vision.

When a creature with binocular vision looks at an object, the eyes must rotate around a vertical axis so that the projection of the image is in the centre of the retina in both eyes. To look at an object closer by, the eyes rotate towards each other (convergence), while for an object farther away they rotate away from each other (divergence). Exaggerated convergence is called cross eyed viewing (focusing on the nose for example) . When looking into the distance, the eyes diverge until parallel, effectively fixating the same point at infinity (or very far away).