Question: Do we see the same with one eye as we do with two?
Answer: Absolutely not!
If this were so, God or nature, in all powerful wisdom, would have given us just one eye instead of two. It would certainly make eyeglasses cheaper, and it would take a lot less time to put on make-up in the morning.
Can we live with just one lung or kidney? Sure, but in spite of the fact that we can survive with just one, we also know that we are not at our full potential, and the body operates much better and more efficiently when we have two of each.
Having two eyes positioned on the front of the head is what allows us to have binocular vision and stereopsis (3D). This has an advantage for hunting, and thus for survival.
The same is true for our eyes. Can we live with one eye? Certainly the answer is also yes, but there are many important benefits from having two eyes. One of the most important is stereopsis or the ability to see in 3D. This can only occur if there are two eyes working together as a team.
Man, along with apes, chimpanzees, lions, and eagles have two eyes located in the front of the head. Indeed, all large predators have their eyes facing forward as compared to other animals, such as many reptiles and amphibians, which have their eyes on the side of their head.
Having binocular vision and stereopsis(3D) is much more than just having better depth perception. A 2013 study in Optometry& Vision Science by Ponsonby, Smith, and colleagues discussed various factors associated with poor stereopsis including prematurity, convergence insufficiency, amblyopia, strabismus, migraine, attention deficit disorder and poor literacy.
The many advantages of good binocularity will be discussed in depth in next chapter .