Humans have two eyes but the final image obtained is one. Both eyes are used for gathering information about our surroundings. Having two eyes comes with various advantages and the main advantage is that we can see the world in three dimensions. The depth and distance can be seen because of the positions of the eyes. The distance between the eyes and our head is approximately 7.5 cm. Both the eyes perceive the image of an object at different angles. This image is then registered on the retina. Then the final two images are sent to the brain for processing. Once the processing is done, a three-dimensional aspect is obtained which enables us to experience the length, width, and height of the object.
What is the purpose of having two eyes?
Close your right eye and mentally note your field of vision with only the left one. Now try the same by closing your left eye. Okay now stop closing your eyes and appreciate the full field of vision available to you on account of your TWO EYES!
This is one of the main advantages of us having two eyes. We have twice as much vision, so to speak. For an average well functioning pair of eyes, this binocular vision has a field of around 170o.
Try another experiment. Now that both your eyes are open, notice the brightness level of your current surroundings. Now alternate between keeping either eye open. Does the brightness level change (field of vision doesn’t very much either does it)? If the functioning of eyes is properly, it probably isn’t. So what’s happening? Your eyes are actually seeing only from one eye at a time but alternating very rapidly. So fast in fact that you aren’t able to notice this. This process is also optimized for double eye vision.
The problem of parallax error in vision is reduced a lot because of this double eye vision. It also enhances our depth perception giving us a very good evolutionary advantage. Also, our ability to detect faint objects is more distinct. Thanks to our ‘two’ eyes, humans are able to enjoy stereoscopic vision. 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.
Human Eye also presents 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!
What is Amblyopia?
Amblyopia is also known as a lazy eye and is defined as the condition in which either one or both the eyes develop abnormalities. These abnormalities start to develop with the child infant or to children who are below 8 years. Newly born with who are underweight or even prematurely born babies have a higher chance of developing amblyopia. When a part of the brain that is responsible for processing the vision fails, this condition develops.