Eye movement stabilizes stimuli on retina
Interestingly enough, an important function of eye movement is not only to consciously direct gaze, but also to keep the visual scene projected on the retina stable. If the same visual scene would move across the retinal image, it would require advanced high-level perceptual processing. Essentially, gaze stabilization is like data preprocessing. This gaze stabilization is the base of the optokinetic nystagmus.