Why Do Cats Eyes Glow?
Anyone who has been outside taking in the view at twilight or during the evening will probably be familiar with the concept of spotting a pair of disembodied, shining eyes peering out of a hedge or from across the road, only to realise that said eyes actually belong to one of the local cats!
The reflective nature of cats' eyes in dusk, twilight and near dark is not totally unique to cats—other animals display it as well—but it is not something that also happens to humans, which is why we often get a start when seeing a cat's eyes suddenly reflecting back at us from nearby!
The same effect can be observed if you take a photo of your cat in dim lighting using the flash—your cat's eyes will appear luminous and almost ethereal in the resulting picture!
But why do cats' eyes glow in the dark, what is the purpose of it, and how does it happen? Read on to learn more.
1. The science behind cats' eye glow: tapetum lucidum
Cats' eyes glow in the dark due to a special reflective layer behind their retinas called the tapetum lucidum. This layer acts like a tiny mirror that reflects light back through the retina, increasing the light available to the photoreceptor cells.
When light enters a cat's eye, it stimulates the retina to create nerve impulses that form the visual image. However, some light passes through the retina and hits the tapetum lucidum, which reflects the light back through the retina, effectively giving the photoreceptors a second chance to detect it. Some of this reflected light escapes out of the eye, producing the characteristic glowing effect visible in dim light or darkness.
This adaptation is vital for cats, enhancing their ability to see in low-light conditions much better than humans can.
2. How tapetum lucidum improves night vision
Cats are crepuscular animals, meaning they are most active during dawn and dusk, times of low light. Their eyes have evolved to be highly efficient during these periods.
The tapetum lucidum effectively amplifies ambient light, allowing cats to see clearly with only one sixth of the light humans require. This superior night vision helps them detect movement and hunt effectively when it is dark outside.
Interestingly, the principle behind the tapetum lucidum has inspired road safety products; cat's eyes reflectors used on roads reflect car headlights back to drivers to mark the centre of the road without impairing their vision.
3. Why cats' eyes can glow different colours
The colour of the glowing eyes depends on the angle of incoming light and the specific structure of the tapetum lucidum. Glows can appear green, blue, yellow, or even a combination of these shades.
This variability is natural and relates to different wavelengths of light being reflected. Each cat's eye may reflect slightly differently, which is why photos or sightings of glowing eyes might show varying hues.
4. Cat colour vision and its limitations
Contrary to the common myth that cats only see in black and white, cats actually perceive some colours, but their range is limited compared to humans.
Cats see within the green and blue spectrum well, but they have difficulty with reds, pinks, and oranges, which may appear as shades of green or blue to them. This limited colour vision combined with excellent night vision is perfectly suited to their crepuscular lifestyle.
5. Near and far sightedness in cats
Cats are primarily short-sighted, meaning their vision is sharper close up than at long distance. This suits their hunting style, which relies on stealth and patience to catch prey nearby rather than chasing from afar.
Objects beyond 15-20 feet become blurry to cats, but their ability to detect tiny movements up close allows them to excel as hunters in their natural environments.
Understanding these visual capabilities helps us appreciate our feline friends' unique adaptations and reminds us of the importance of respecting their natural needs and behaviours.
If you're interested in finding a Maine Coon kitten or learning more about cat breeds and their special traits, always seek advice from reputable breeders or rescue centres who prioritise the welfare of the animals.
What do cats see when they look at humans?
Cats see humans quite differently to how we see each other. Their vision is optimised for detecting movement at low light rather than resolving fine detail, so they likely perceive you as a large, somewhat blurry shape. Cats are less sensitive to red wavelengths — skin tones appear muted and greenish rather than warm. What they do register very clearly is body language: your posture, speed of movement, and the direction of your gaze all communicate intent in ways cats read instinctively. Direct eye contact is interpreted as a challenge or threat; blinking slowly signals non-aggression. Cats are thought to see their owners more as giant, benign companions than as members of a different species — their social behaviours toward humans (rubbing, slow blinking, bringing prey) mirror how they interact with other cats they trust.
Inbuilt night-vision goggles
The tapetum lucidum acts as a biological mirror behind the retina, reflecting light back through the photoreceptor cells for a second pass. This roughly doubles the chance of each photon being detected, allowing cats to see in light levels around six times dimmer than the human minimum. Their pupils can dilate to nearly the full width of the eye, maximising light intake — and contract to a vertical slit in bright light for precise control. The trade-off is reduced sharpness: cat vision is estimated at around 20/100 compared to the human norm of 20/20, meaning fine detail at distance is blurred. Cats are also somewhat short-sighted, with their vision sharpest at close range (30–60cm), well suited to tracking and striking prey within paw reach.
Related articles
