It is believed that the ability to perceive color aids these animals in obtaining food. Rods are detectors of tone, i.e., gradations of lightness and darkness, and cones are sensitive to color. Although the cones in the rat eye are shown to have sensitivity to green and UV light, behavior experiments have demonstrated that rats lack color vision. Rats have laterally-placed eyes that sit on the sides of their heads. This placement allows very little overlap of the visual field of each eye.
Rats do have some binocular ability that is limited to distant objects.
Binocular vision is the fusion of separate images captured at slightly different angles by each eye, which makes depth perception possible. Part of the reason why rats have such poor eyesight is because generally the eyes of small and nocturnal animals are far-sighted, which signifies a lack of need for optical quality. This phenomenon is clearly illustrated in the observance of certain strains of rats that undergo spontaneous retinal degeneration soon after birth. Compared to normal, sighted rats, these animals show no differences in behavior under daylight conditions. Compare this behavior to that of a blind bird or kitten, both of which would be virtually helpless without sight.