Cats have excellent vision that differs from human sight in some key ways. This article will explore how cat eyes are uniquely adapted for seeing in low light compared to humans. We’ll cover topics like the anatomy behind cats’ vision, how it helps them hunt, differences in field of view, and comparisons of cat vs. human eyesight. The article will outline how cats see better at night but less sharply during the day versus humans, allowing them to thrive as nocturnal hunters.
Cats’ Eye Anatomy
The feline eye has several unique anatomical features that allow cats to see well in low light conditions. Cats have very large eyes relative to their head size, which provides a larger retinal surface for light detection (The World Through the Feline Eyes 2022). They also have a reflective layer behind the retina called the tapetum lucidum that bounces light back through the retina for a second pass at photoreceptor stimulation (Merck Veterinary Manual).
Additionally, cats’ pupils open very wide to let in more light – much wider than human pupils. Their lenses are more spherical, which improves their ability to focus in low light. Cats also have a high density of rod photoreceptors compared to humans. Rods detect low light levels but not color. The area of highest rod concentration is the area centralis in the center of the retina (Merck Veterinary Manual).
Rod-dominant Retinas
Cats have a high proportion of rod cells in their retinas compared to humans, allowing them to see better in low light conditions. Rod cells function optimally in dim light as they contain a light-sensitive pigment called rhodopsin that absorbs photons efficiently even with little light present.
According to a retinal cell density study, approximately 75% of the neurons in the inner nuclear layer of the cat retina are rod cells [1]. In contrast, only about 5% of the photoreceptors in the human retina are rods.
With their rod-dominant retinas, cats can see at light levels 6-8 times lower than humans. Their vision is optimized for dawn and dusk conditions when prey animals are active. This gives cats an advantage for night hunting.
Cones for Day Vision
Cats have cone cells that allow them to see colors and details during the day. Cats have two types of cone cells – one tuned to violet light and one tuned to green light (Are Cats and Dogs Colourblind?, 2018). This means cats are dichromats, meaning they have two types of cone cells and can perceive colors, albeit not the full spectrum that humans can see with three cone types (Cat colour vision: evidence for more than one cone process, 1970). The cone cells contain photopigments that respond to different wavelengths of light, allowing cats to discriminate between some colors.
Studies using neutral point testing have shown that cat color vision is similar to red-green color blindness in humans, though they still have some ability to distinguish between hues (Cat colour vision: evidence for more than one cone process, 1970). The cone cells allow cats to see best during daylight hours when there is plenty of light. Cone cells are concentrated in a central band in the retina, providing detailed vision in brighter light (Cone signals in the cat’s retina, 1977).
Cats See Best at Dawn/Dusk
Cats’ vision is specially adapted to see well in low light conditions, like at dusk and dawn. Their retinas contain a high concentration of rod photoreceptor cells, which are extremely sensitive to light and allow cats to see in near darkness (Purina). Rod cells collect all available light, enabling cats to see when humans can’t. But they come at a trade-off of less visual sharpness.
Cats also have a reflective layer called the tapetum lucidum behind their retinas that acts like a mirror. It bounces light that passes through the retina back onto the rods for a second pass, essentially doubling the amount of light input (USA Today). This gives cats better vision in dim conditions, boosting their ability to hunt and navigate in the twilight hours of dawn and dusk when prey is active but most predators can’t see well.
While cats can’t see total darkness, their rod-dominant eyes are significantly more sensitive than human eyes at night. They may not have true night vision, but cats do see best when the light is low at dawn and dusk.
Field of View Differences
Cats have a significantly wider field of view compared to humans. While humans see about 180 degrees around them, cats can see almost 200 degrees. This gives them better peripheral vision to detect threats and movement.
However, cats have less binocular vision overlap than humans. Binocular vision refers to the area both eyes can see at once, allowing depth perception and focal vision. Humans have about 140 degrees of binocular overlap, while for cats it’s only about 30-50 degrees [2].
So while cats have fantastic peripheral vision for detecting motion, their focal vision for observing details directly in front of them is more limited compared to humans. This difference allows cats to have great awareness of their surroundings while also precisely focusing on certain objects or threats when needed.
Hearing and Smell
Cats rely heavily on their senses of hearing and smell to hunt and navigate the world around them. According to the Cat Senses article from Paws Chicago, cats’ sense of hearing is much more sensitive than humans, with a hearing range of approximately 45-64 kHz compared to humans’ range of 20-20kHz.
Cats can move their ears 180 degrees and independently, allowing them to pinpoint the source of sounds very accurately. Their sensitive ears pick up high frequency sounds from birds, rodents and other prey that humans can’t detect.
According to the Your Cat’s World article from Hartz, cats also have a very advanced sense of smell, with nearly 200 million odor-sensitive cells compared to only 5 million for humans. Their sense of smell is 14 times better than humans, allowing them to identify scents we can’t detect.
Cats use their exceptional hearing and smell to hunt prey even in darkness. These senses give cats an advantage for nocturnal hunting and navigating their environment.
Vision Impact on Hunting
A cat’s vision gives them key advantages when hunting. Cats have excellent night vision due to having a high concentration of rods in their retinas, which allow them to see in low light conditions (Crowley, 2019). Their eyes have a special reflective layer called the tapetum lucidum that reflects light back through the retina, improving night vision. Cats also have a wide field of view of about 200 degrees, giving them better peripheral vision to spot prey (Lifelines, 2015). Their slit-shaped pupils can open wide to let in more light at night. All of these visual adaptations allow cats to excel at hunting even in dim light when prey animals have a harder time seeing them coming.
Human vs. Cat Vision
Human and cat vision differ in a number of key ways. Cats have superior night vision compared to humans. Their retinas contain a high concentration of rods, which allow them to see in low light conditions [1]. Humans, on the other hand, have more cones concentrated in their retinas, providing them with better color vision and visual acuity in daylight[2].
Cats also have a wider field of view than humans do. Their field of view is about 200 degrees, while the human field of view is around 180 degrees[1]. This gives cats better peripheral vision to detect predators and prey. However, human vision has greater visual clarity and ability to perceive fine detail.
In addition, cats do not see color as vividly as humans. They have difficulty distinguishing between colors on the red end of the color spectrum. Their world appears more blue and green compared to how humans perceive color[2].
Overall, cat vision is optimized for hunting at night, while human vision excels at daytime activity requiring visual acuity. Their differences highlight the unique evolutionary paths of feline and human vision.
Conclusion
The unique structure of cats’ eyes allows them to see much better in low-light conditions compared to humans. Cats have a high concentration of rods in their retinas, which are responsible for night vision. They also have a reflective layer that bounces back any stray light that enters their eyes. While humans rely primarily on cones for daytime color vision, cats have fewer cones and superior rods. This gives cats excellent night vision and makes them adept hunters in dim lighting. However, it means their vision is not as sharp during the day. Cats have a wider field of view than humans, almost 270 degrees, which also aids their hunting abilities. Their vision is adapted for detecting motion and following prey, even in very dark conditions. While cats do not see total darkness, their low-light vision capabilities are far superior to those of humans.
