Binocular Vision

The term ‘binocular vison’ is derived from the Latin words bini meaning double, and oculus meaning eye.

Binocular or double vision allows an animal to see one image, through two eyes, as three-dimensional. This type of vision doesn’t apply to animals who have eyes on opposite side of their heads. It is a type of vision that requires both eyes to be aligned and focus on the image. In this way, the brain perceives what both eyes are seeing as a single image.

While each eye still has its own line of vision, functional binocular vision fuses the two eye pathways. Binocular vision is the standard vision type for mammals, including humans. With two eyes, we can see nearly 180 degrees.

How Does Binocular Vision Work?

When the two eyes work together, it allows the animal to see a single clear image, known as stereopsis. The left eye will perceive the view from one angle, while the right eye perceives it from another. It gives the animal excellent depth perception.

In comparison to monocular vision (one eye), binocular vision is best for animals that rely on good depth perception to survive.

If one of the animals’ eyes were to be covered, the animal can still see out of one eye. However, their vision from only one eye won’t be as good and it will give the animal poor depth perception.

Animals with Binocular Vision

Many mammals have binocular vision, including humans. Both prey and predatory animals can have binocular vision at varying degrees.

• Humans
• Apes
• Snakes
• Cats
• Dogs
• Badgers
• Rabbits
• Pandas
• Owls
• Sharks
• Eagles

Advantages of Binocular Vision

Binocular vision is quite advantageous for many animals. In addition to better perception of depth, it enables hand-eye coordination and enhanced visual field. It allows for interpretation of different depths and distances between objects. It is normal for many animals to have at least some binocular overlap in their vision, but not all animals have strong binocular vision. This depends on how much their species relies on it for survival.

Below is a list of possible advantages of binocular vision:

• Allows for binocular summation or improved visual performance.
• In the case of one eye getting damaged, the other eye acts as a backup eye, though vision will be slightly impaired.
• Allows for good depth perception and distinguishing distance between objects.
• Allows for view of the object behind the current object being viewed within the appropriate distance.
• Enables a wider field of view.
• For hunting animals like owls and eagles, binocular vision allows them to make perfectly timed attacks by gauging the distance between them and their prey.
• Small prey animals like rabbits can make more informed decisions about how to move in their environment.