Eye is one the most important organs of the body.The human eye is an organ which reacts to light for several purposes. The visual system in the brain is too slow to process information if the images are slipping across the retina at more than a few degrees per second . Thus, for humans to be able to see while moving, the brain must compensate for the motion of the head by turning the eyes.
Another complication for vision in frontal-eyed animals is the development of a small area of the retina with a very high visual acuity. This area is called the fovea, and covers about 2 degrees of visual angle in people. To get a clear view of the world, the brain must turn the eyes so that the image of the object of regard falls on the fovea. Eye movements are thus very important for visual perception, and any failure to make them correctly can lead to serious visualdisabilities.