What Is the Use of Having Two Eyes?
The fact that we have binocular vision – that is, vision through two eyes – helps us to perceive depth. Our eyes measure about two and a half inches from pupil to pupil. Therefore, the right eye sees more of the right side of an object, and the left eye sees more of the left side. This gives us stereoscopic vision, or the ability to judge depth.
Stereoscopic vision enables us to see that an object is solid or deep, or in front of or behind something else. Try looking at an object with only one eye. You will find that it looks much flatter than it does with two eyes.
The two eyes provide vision which is additive by enabling a wider field of vision when using two eyes compared to one. The two eyes also cooperate in the overlapping visual fields enabling stereoscopic vision by blending slightly dissimilar views of an object which is then seen singly and with depth.
Some animals with two eyes like rabbits and buffaloes have 360o degree field of vision but they do not have stereoscopic vision. This is an advantage only available to animals with two eyes in the front of their head like us humans.
Two eyes also present an aesthetic advantage. Symmetry is always considered to be more appealing than asymmetry. Two eyes satisfy this condition. Apart from the significant advantages mentioned above, there is another extremely important advantage of having two eyes. If one dies, there’s always a spare!