Unlike humans, a cat’s eyes are designed to work best in darkness – they have an amazing power to see well enough to hunt in the dimmest of light. In fact, their eyes are six times stronger than the human eye in terms of night-vision. This is because their eyes have a very high concentration of rods (photoreceptor cells) as opposed to human’s cones which only work well in bright light. Because of the high rod count in their eyes, they have fantastic night vision.
Their great night vision explains why they are best able to hunt during the darker hours, when their prey is less likely to see them.
Their highest concentration of rods falls across the centre of their retina giving them great peripheral vision and this helps them pick up sudden sideways movements (such as a creature sensing them and rushing for cover).
Human beings use the cones in their eyes to pick up colour during the day, whereas cats, even though they are not colour blind, do not see colours in bright light as well as humans and other daytime animals do.
The human eye lets in light by decreasing or increasing the size of the pupil. Cat’s eyes do the same, except they don’t have a round pupil controlled by only one muscle. Instead, they have two muscles, one on either side, which work to narrow the pupil in bright light, but can become as wide as the eye itself in dark conditions. This allows a large amount of light to reach the retina, much more than the human eye.
All of this goes a long way in explaining why cats are simply fabulous at chasing that infamous red dot!
-Article posted by Phillipa Mitchell