Cat vision is incredible. Cats have very large eyes. They work most effectively at night when mice are most active. Rods— photoreceptors responsible for black-andwhite vision in dim light—outnumber cones (responsible for color vision) in the cat’s retina by 25:1 (in humans the ratio is 4:1).
Cats have color vision but it is not as important. Most important for them is their night vision. They can see blues and yellows, but reds and greens probably appear as grays. In daylight, the pupils shrink to vertical slits to protect the eyes from glare.
Cat vision is not so sharp. Focusing such large eyes takes effort and cats are generally farsighted, unable to see clearly within about 1ft (30cm) of their eyes. Their vision is much more attuned to detecting movement. Cats have forwardfacing eyes like other predators. Their total ﬁeld of vision is about 200º, with an overlap between the eyes of 140º. This overlap gives the cat binocular vision, allowing it to see in depth and to judge distances accurately, which are essential for success when hunting.
Night Cat Vision
In the dark, a cat’s pupil expands to an area three times larger than a human’s dilated pupil, allowing the tiniest glimmer of light to enter the eye. A cat’s night vision is enhanced by a reﬂective layer behind the retina. That layer is called the tapetum lucidum. Any light entering the eye that not caught by the retina bounces off the tapetum and travels back through the retina, increasing the eye’s sensitivity by up to 40 percent.
The tapetum appears as a bright golden or green disk when a source of light strikes a cat’s eye at night.
Eye and vision
A cat’s eye is a hollow ball ﬁlled with clear jelly, or humor, that lets light pass through. Light rays are focused by the cornea and lens and form images on the light-sensitive retina.
Eye colors and shapes
Cats’ eye colors come in orange, green, and blue tones. Some cats have odd-colored eyes. Eye shape varies from round to slanted, with some Eastern breeds having very pronounced slants.