accommodation (stereoscopic)

The eyes ability to refocus on points at different distances. This is linked by muscle reflex with convergence/divergence, the change of angle between each eye s line of sight, focusing on something far, then near, causes a change in the angle. Watching a 3D program requires accommodation at a fixed distance (the screen) while eye convergence and divergence changes -- something that is not normally done and can be headache inducing.