14 November 2022
Dogs’ vision isn’t as bad as you think unless they have a birth defect or disease or have experienced trauma that affects their vision. It is also a misconception that dogs can only see in black and white.
Achromatopsia is the term for someone who can only see black, white, and shades of gray — not to be mistaken for color blindness. Three types of photoreceptors, called cones, must be present in the eye to see colors normally. Reflected light enters the eye and activates different kinds of tiny photoreceptors, which transmit signals to the brain to determine what color we see. The problem with color blindness is that some photoreceptors do not work correctly or are missing. Therefore, an individual is color blind if he or she cannot see some colors properly.
In humans, cones are the parts of the eye that allow us to see colors. Dogs, however, only have two types of cones. Thus, humans can see more vivid colors and a greater variety of colors than dogs. Dogs don’t, however, see in black, white, and gray. Instead, dogs have two types of cones that allow them to see shades of blue, yellow, and brown, along with black, white, and gray. Due to these cones, dogs cannot see shades of red or green. Instead, they see shades of brown or gray.
When choosing a toy for your dog, choose shades of yellow and blue because dogs cannot see red and green colors. Dogs are more attracted to these colors because they can see their true hues. This is why yellow tennis balls are a big hit among dogs, even though they do not see them as brightly as humans do.
While cones are important for seeing colors, other parts of your dog’s eyes play a different role. In your dog’s retina, rods are another type of receptor that is much more prevalent than cones. The rods detect the brightness and determine how well a dog can see at night. Dogs can also use them to determine the size and shape of objects and helps with peripheral vision. As dogs’ eyes have more rods than cones, their night vision is much better than their ability to see colors during the day.
In addition to the rods and cones found in the retina, the tapetum lucidum is a part of the eye located behind the retina. This reflects any light that enters the eye and enhances a dog’s night vision. Ever notice when you use the flash on your camera, and your dog’s eyes seem to glow golden green? That’s the tapetum lucidum bouncing the flash back into the camera.
Even though dogs have excellent night vision, their eyesight is a different story. A dog’s visual acuity is typically 20/75, compared to 20/20, the average human visual acuity. So if a person can see details of an object from 75 feet away, a dog must be closer to 20 feet out to see the same details.
Considering all these factors, you might think your senses are superior to your dog’s since you have better visual acuity and can see more colors, but that is not true. Not only can your dog see well at night, but his excellent smell and hearing more than make up for any Mr. Magoo-like tendencies.