Determination of the human visual field

The part of the surroundings perceived with an unmoved eye is called the visual field. In contrast, the field of view is that part of the surroundings perceived by the eyes when allowed to move freely but without moving the head. Depending on the uneven distribution of rods and cones in the retina (only cones in the centre and only rods at the periphery, with mixed rods and cones in between), the size of the visual field varies with the colour of the test object. The extent of the visual fields of both eyes and the position of the blind spot are determined with the aid of a perimeter.