Are a dog’s eyes the same as a human’s?

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Dog eye

No, dogs’ eyes are not the same as human eyes but they are very similar to cats’ eyes. Inherently, domestic dogs are more active at dawn and dusk. They are crepuscular animals. As a result their eyes have evolved to work best in dim light and to see movement as prey animals.

Dog eye

Dog eye. Photo: Twenty20 – @amalagon1

Rod-rich

The retina is made up of a higher ratio of rods to cones than for humans. The cells in the retina called “rods” are those which provides black-and-white vision in dim light while the “cones” pick up the colour. So the dog’s eye is “rod-rich”. Humans are what is called “diurnal” in their behaviour which means active during the day. This is atypical for mammals.

Pastel shades

Because the retina of the dog’s eye contains cells sensitive to colour, they must see colour but it is believed that they are pastel shades or tints and the expert are not sure of the vibrancy of these colours. They do appreciate colour nonetheless.

Reflective layer

Also like cats but unlike humans, dogs have a reflective layer called the tapetum lucidum behind the retina which reflects light back into the retina which means that it captures more light which in turn means that dogs see better than humans in dark conditions. You will see the reflective nature of their eyes if a pinpoint light source shines into the eye and is reflected straight back out of the eye at 90°. Car headlights will do this.

Movement

As is the case for cats, a dog’s eyes are more sensitive to movement. It is said that animals that are prey to dogs have evolved to remain still when at a distance because dogs can’t see them such is their vision attuned to seeing movement and not that good at seeing sharp detail at a distance. They become invisible to a dog. So if a dog owner remains static at a distance of 300 yards from their dog, their canine companion won’t be able to see them. However, at a much greater distance of about a mile a dog is able to see the movements of a person such as waving their arms around.

Lastly, dogs have a wider angle of vision than humans. Greyhounds have a visual range of 270°. Typically dogs have a range of 250°. For flat-faced dogs, such as the bulldog, the angle of vision is reduced further but it is still greater then the human’s at 180°. This is the same for cats.