When the eye looks at a specific point or object, that point is seen clearly. Other objects within a large area away from this fixation point can also be seen, but less clearly. The area that can be seen around the fixation point, without moving the eye, is known as the field of vision. The extent of the field is limited inwards by the nose, above by the brow and below by the cheek. The visual field thus has its greatest extent outwards from the side of the head. The field of vision of each eye overlaps to a large extent so that objects in the centre and towards the inner part of each field are viewed by both eyes together. Because the eyes are set slightly apart, each eye sees objects in this overlapping part of the field slightly differently. It is because of this slight difference that objects can be perceived as three-dimensional.
The space within which an object can be seen while the eye remains fixed on one point.