Cats see even better than dogs in the dark and are known for having great nocturnal vision.
A dog’s eye is made up of the inner retina, pupil and lens, the middle iris, and the outer cornea.
In dogs, vision is determined by a variety of factors, including: ability to perceive motion and light, perception of form and color, sharpness of vision, depth perception, field of view, and visual perspective.
Dogs and cats have a special reflective layer in the back of the eye known as the tapetum.
Cats have a tapetum that glows yellow-orange or yellow-green; however, the color varies, just like their irises.
Most dogs have a partial tapetum. So, you should know that their reflective structure covers only about 50 percent of the back of the eye. Cats have a larger surface area of their fundus covered with the tapetum. This is one of the main reasons that cats see better than dogs at nighttime.
How well can dogs see in the dark?
The majority of dogs have a visual acuity of 20/75, meaning that the dog needs to be 20 ft away to see a toy that a human can see at 75 ft away. Basically, your dog needs to be closer to see the toy clearly.
Dogs also have fewer cones than humans do, but have far more rods. Cones are the cells in the eye that detect color and fine detail. I learned during veterinary university that rods are the cells that detect movement and shapes, especially in dim conditions.
Dogs can see pretty well in the dark and are considered to have excellent night vision. You might be surprised to learn that dogs see better in the dark than humans.
“Dogs can probably see in light five times dimmer than a human can see in,” said Paul Miller, a clinical professor of comparative ophthalmology.
However, dogs still require some light in order to see (in the dark).
On the other hand, dogs’ ability to see color is quite limited compared to ours. Dogs can’t see green and red all that well, but they are very good at distinguishing between variations of yellows and blues.
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Why do dogs’ eyes glow in the dark?
Dogs’ eyes glow in the dark due to a structure in the back of the eye called the tapetum lucidum, a Latin term that translates to bright or shining tapestry. It is located between the optic nerve and the retina.
The tapetum works to increase the amount of light in the retina. This layer is like a mirror reflecting light through the eye.
If your dog is stressed or excited, their eyes may dilate more, allowing for more of this glow to show in photos
This tapetum lucidum may be orange, blue, green, yellow, or variations in between those colors. The tapetum also accounts for the brightness of a dog’s eye reflection.
The mineral concentrations in the tapetum lucidum affect the colour that is reflected through.
It is known that dogs with blue eyes and white coats (like Australian Shepherds and Huskies) can give off a red-eye effect during the night.