As dreading it can be the sight of glowing eyes of your dog in the middle of the night is scary as hell and can send jitters throughout the body. Dogs have always been and hopefully will be man’s most loyal friend. They are sensible, fun and are not gullible as man’s feline friends. These canines are always thought to have impeccable night vision which lets them see in the dark light easily.
Well, it is true to some extent, but dogs are not better at night vision than your cat. But one thing is for sure that the night vision of a dog is much better than humans.
Before going ahead, there are a few dog eye parts you should know about:
Rods: these are the light and motion sensitive cells that help in differentiating between light and shadow. These rods help dogs to see the black and white color.
Tapetum lucidum: at the back end of the eye dogs like many other nocturnal and feline animals have Tapetum. The function of Tapetum is to absorb the light which is missed by the rods and reflect it back to the retina, which further allows the retina to absorb more light ultimately allowing your dog to see better.
Photoreceptors: the photoreceptors are small cells in your eyes that respond to light. The primary function of these receptors is to transfer the messages obtained through vision and instructing the brain take action.
Visual streak: it refers to the area of sight of an animal, the dogs have a higher visual acuity due to the higher number of vision cells spread across the retina.
These two are not the only parts of a dog’s eye, but these are relevant for our topic. So, let’s begin:
Night Vision or not:
Dogs have large pupils; this allows them to absorb more light than humans allowing dogs to see things in 5x dimmer light than what humans can see. Where humans have to buy one of the best night vision scopes to see in darker lights, the dogs can see things clearly just because of their larger number of rod cells.
That scary glow has moniker eyeshine, although it is more of a frightening shine. This eyeshine is also a factor that helps dogs see better in the dark light. The dogs’ Tapetum lucidum lies in the middle of the retina and the optic nerves. The benefit of this position of Tapetum is that it increases the amount of light forwarded to the photoreceptors, which gives dogs the ability to see better in lower intensity of light.
The glow is also seen due to this reaction of Tapetum, all the animals that have Tapetum lucidum will have glowing eyes. This marvelous attribute of your dog is the gift of evolution, with centuries of hunting and living in the dark, animals like dogs and other nocturnal beings have developed this ability to see in the dark and have glowing eyes. Scary!
First off, what is depth perception?
Have you ever wondered how is it you can see an object still afar with clarity and precision? The answer is through depth perception, it is an inherent trait in humans whereby they have the ability to perceive objects in three dimensions and gives us the ability to judge the distance of an object, place or anything else.
A dog’s depth perception is lower than humans; the reason is that for apt depth perception the eyes need to be closer to each other. The dog’s eyes are a little distant than humans which reduces their depth perception. Other animals like rabbit do not have depth perception, as their eyes can see in different directions at once and for depth perception, the eyes need to look in the single direction that is straight ahead.
What lacks in depth perception is compensated by a peripheral vision in dogs. Humans have a 180-degree vision as compared to dogs that have 240-degree vision. The Visual streak of dogs allows them to see a wider area than humans. This considerably improves the horizon vision of dogs and helps them see objects at a distance clearly and with precision.
The lower depth perception but wider visual streak goes a long way in assisting dogs to chase moving objects. It has been observed if a hand is waving at the distance of more than a mile; the dogs can observe it and react accordingly. This property is seen mostly in guard dogs which can detect any moving object in the middle of the night and chase it as long as the object stays in his 240-degree vision angle.
All of these properties of a dog and combined with evolution is seen in the Afghan hounds and greyhounds which are avid hunters and have gained the ability to see through darker forests clearly.