Why Do We Have Two Eyes?

May 15, 2024

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Table of Contents

Introduction

As humans, we have two eyes and require the usage of two eyes even though we can still have a sense of vision if we cover one of them. In this article hence we are going to discuss why we have two eyes and the necessary explanation for it. This is because two eyes help in enabling two different things in our brain, one being depth perception and the other being an enhanced field of view. So essentially, human eyes have a field view of 170 degrees.

Depth Perception

Though we have two eyes, we essentially see one image at one time. It is our brain that sees the image sent through one eye and makes sense of the information. Our brain alternates the data sent from both eyes and helps us to see the third dimension. Depth perception helps us to see the distance between two objects in a field of vision.

The Objective of Having Two Eyes

Close your left eye and look at the field of vision only with your right. Similarly, repeat the process with the right eye. Now open both of your eyes and note how you can view the field of vision. One of the most important purposes of having two eyes is we have enhanced vision. Our binocular vision has a field of about 170 degrees.

Since we have the double-eye vision, our parallax error in our vision is significantly decreased. With double-eye vision, our depth perception is also improved, thereby providing us with an evolutionary benefit. Moreover, we can also recognize faint objects much more easily with our double-eye vision. Most animals, like rabbits and cows, essentially have 360-degree vision but not stereoscopic vision like us.

Understanding Eyesight Through Basic Activities

You can perform certain activities to check why we need two eyes.

Activity 1: Checking Brightness Level

Try to close one of your eyes and check the level of brightness. Now try to switch between eyes. If you do not have any inherent eye problems, then you would see there is no difference in the brightness level that you see with two different eyes. Essentially this proves that as humans, we see from one eye at a time, and the time to switch between two eyes is really fast.

Activity 2: Checking Depth Perception

For this activity, you would need various objects of various sizes and shapes. Now close your eyes while asking somebody to place the objects in front. Then open one eye and try to touch a particular object. You would see that you would struggle in trying to touch the object.

Now try to experiment with both eyes, and you will see that there is no such struggle. This is because our brain needs both eyes to determine a particular position of the object. With just one eye, it is difficult to determine the object, and thus, we struggle.

Retina and its Functions

The retina converts light that essentially enters our eyes into electrical signals to our optic nerves and creates images. The retina tries to capture the light and helps to view the images.

Light passes through the lens at the front of the eyes and hits the retina. Retina has photoreceptors that react to the light and convert it into an electrical signal. This signal then moves to our optic nerve and into the brain.

The retina essentially works like a translator. When the light hits, the retina converts the signal and processes it to the brain. If you have a damaged retina, your eye will work to a certain extent, but your brain will not be able to receive the information that it requires to create images.

Types of Visual Impairment

We should have two eyes in good condition to have proper vision. However, there are certain visual impairment issues we might face. Two of them are discussed below.

1. Diplopia

It is a type of visual impairment we face when two eyes are not aligned properly, and there is a visual deficit that prevents the brain from interpreting the information. Diplopia or double vision can be due to an injury that affects our small muscles and controls eye movement. This can be corrected with strengthening exercises. However, sometimes it can also be due to nerve damage, and it’s better to consult an ophthalmologist.

2. Amblyopia

This condition is also known as lazy eye, where one or, in some cases, both eyes acquire certain defects and abnormalities. These abnormalities start to appear in infants or children who are under the age of 8. Infants who are born premature or underweight are likely to face this eye defect.