Since dogs hear better than us, the assumption that they can probably see better than us makes our article How Dogs See the World even more interesting. Please continue reading...
You might be under the assumption that because dogs hear better than us, they can probably see better than us. Of course, this doesn't have to be the case. Let's take a look at the anatomy of a dog's eye and how canine vision compares to ours; from seeing colors to side vision to seeing in the dark.
Canine Eye Anatomy
The anatomy of a dog's eye is very similar to that of a human eye. For example, dogs have an upper and lower eyelid, just like humans.
Sclera: This is called the white of the eye. However, it is a hard, fibrous layer.
Cornea: The thin, transparent layer at the front of the eye that is easily injured.
Conjunctiva: The lining of the eyelids, which can become inflamed and pink when dogs are excited, have allergies or eye infections.
Iris: Containing the smooth muscle of the eye; adjusts the light entering the eye and controls the size of the pupil. It is the colored part.
Pupil: The black area in the center of the iris; contracts in bright light. It expands in dim light.
Lens: Located behind the iris. Changes shape to focus light on the retina.
Retina: Located at the back of the eye. It contains rod photoreceptors that detect light and motion. It contains receptors called cones that detect colors.
However, dogs have eye structures not found in humans:
Tapetum lucidum: Located behind the retina, the tapetum lucidum reflects light off the retina, increasing the light available to the photoreceptors. Animals see better at night. When light is reflected from the animal's eye, it makes the animal's eyes appear to glow.
Third eyelid: The third eyelid, known as the nictitant membrane, is whitish in color and is located at the corner of the eye and near the nose. It helps protect the eye from scratches. It moves over the eye when the dog blinks to help produce tears.
What are the Colors of a Dog's Eye?
The iris or colored part of a dog's eye can be brown, blue, gold, and hazel. Brown is the dominant color for most dogs. Dogs can have two different eye colors.
If a dog has light-colored (blue) eyes, it does not mean that they have vision problems. Iris pigmentation varies depending on the breed, the color of the face, genetics.
Do Dogs Have 20/20 Vision?
Dogs cannot see objects as well as humans. Normal human vision is 20/20. Most dogs have a visual acuity of 20/75. A dog needs to be 20 feet away to see an object; a person needs to be able to see it 75 feet away. Labrador Retrievers, a breed commonly used by humans as seeing eye dogs: Labrador Retrievers have better vision, closer to 20/20.
Are Dogs Near-Sighted or Far-Sighted?
A dog's vision is blurred. If the dog were human, it would be considered myopic. It would need glasses to see the blackboard in the classroom, the road sign on the road and objects in the distance.
Can Dogs See Movement Well?
Dogs have more rods in their retinas than humans. The rods are sensitive to shape, movement and dim light. Dogs can see moving objects much better than stationary objects. They have 10-20 times more motion sensitivity than humans.
Dogs can pick up small changes in body posture and movement. This is one reason why dogs are trained with silent cues using hand gestures.
Can Dogs See in the Dark?
Dogs have several anatomical advantages that allow them to see better in the dark than we can:
- More rods in their retina that function better in dim light
- Larger baby allowing more light to enter the eye
- A lens that is closer to the retina and makes the image brighter
- Tapetum lucidum, which reflects light and provides better night vision
Can Dogs See Colors?
Dogs only see colors in shades of blue and yellow, and because they can only see two colors; they have dichromatic vision. They can see shades of gray. The colors red, orange and green are outside of a dog's color spectrum. Dogs cannot see these colors. Hunters wear orange to be seen. Humans have what is called trichromatic vision, which means we can see many more colors than dogs.
Do Dogs Have Side Vision?
A dog's eyes are slightly farther away than ours, at an angle of 20 degrees. This results in greater vision and increased peripheral (side) vision in a dog.
How Do You Check a Dog's Vision?
Dogs cannot read an eye chart. They do not need to be able to read or write. Since they have less need for good vision, known as visual acuity, checking a dog's vision is very simple.
If a dog can enter a room through a door or navigate an obstacle course in an examination room in bright and dim light, they are said to have good vision. Canine eye specialists or veterinary ophthalmologists can perform dog eye examinations, check vision and perform surgery to help dogs see better, such as cataract surgery.