The Science Behind The Human Eye

Human eyeBe honest with yourself. Is it possible that you’ve taken your eyes for granted?
Have you ever thought about how amazing the human eye is and just how are we able to see those millions of different colors and objects of different shapes and sizes?

The eyes are one of the most fascinating parts of the body.


In fact, the eye is the second most complex organ in our body, second only to the brain.
It is also the fastest muscle in our body. Human eyes can process, an image in as little as 30 milliseconds.
You might think that a DSLR camera with a resolution of about 120 megapixels is awesome, but that’s nothing when compared to the resolution of your eye, which is 576 megapixels.

To better understand how you see things, first you need to understand the role that light plays in your vision.


The light bounces off of things and goes through your eyes. It enters your eyes through the cornea, which is a clear thin layer on the outside of your eye. The cornea directs sunlight towards your pupil and iris. (which is the color part of your eyes and the pupil is the little dark circle right in the center) The iris and pupil have to regulate the amount of light that gets into your eye. The iris contracts and dilates, changing the size of the pupil.

This is why sometimes our pupils look bigger or smaller, depending on how much light is entering our eyes.


For example, if you’re standing in bright sunlight your pupils will be smaller to lead less light into your eye. But if you are in any dimly lit room, your pupils will expand to allow the maximum amount of light to get through. After the light rays move through your pupils they pass through the lens of your eyes, which are directly behind your irises. The lenses are flexible and they’re able to change shape to help focus on objects at different distances. The lenses guide light rays to your retinas at the very back of your eye. The retina is a thin layer of tissue that is covered with millions of light sensitive cells, called rods and cones.
Each person has between six to 7 million cone cells and around 120 million rod cells, concentrated on a spot of the render no bigger than three tenths of a millimeter. Rod cells are responsible for your night vision, they also allow the eyes to detect motion.
Cone cells are responsible for daytime vision and they detect color.
There are three types of cone cells, depending on how they respond to red, green and blue light. Combining these three signals in the brain creates millions of different colors and shades.
Once the image is focused on the responsive part of the retina, the energy in the light creates an electrical signal. These signals pass along the optic nerve, that connects the eye to the brain, to carry information about how bright and colorful the images are. That information is sent to the brain visual cortex, which is responsible for the images that we observe.

Human eye blueThankfully, these processes happen extremely quickly, so that we can see things in real time.

Our vision is such a complex phenomenon, that almost half of our brain is responsible for generating vision. Other creatures have very different eyes, or no eyes at all, and many humans have eyes that are unable to process images properly.

Some people are colorblind, while others experience complete blindness.


One in twelve men and one in two hundred women are affected by some form of CVD or (color vision deficiency). It affects about 4.5% of the entire world population. There are multiple potential causes of color blindness, the most common being the genetic disorder (the condition is inherited) from the mother of the individuals. In this case, issues that cause color blindness are the X chromosomes. Others include an injury to the eyes or a disease such as glaucoma, cataracts or macular degeneration.
Color blindness is a recessive trait that can be overwritten by another dominant X chromosome. For example, females have two X chromosomes and the recessive trait can be present in one of these X chromosomes. The awesome thing of having two of those is that one can compensate for the other.
On the flip side, males have only one X and one Y chromosome. This is why men are much more susceptible to color blindness.
People with CVD can have many difficulties with simple tasks of life, such as writing, selecting clothing or even finding work. Because of the fact, these individuals may not be allowed to have several jobs that require them to have color perception.
Human eye brown

Here are some tips how to keep your eyes healthy:


Eat well. Remember we are what we eat, so eating healthy can actually help to keep those precious jewels in good working order.
Get a good night’s rest. This is also crucial and without it we put a heavy load not only on our eyes, but on the whole body. For all you gamers or night workers: some sleep is better then no sleep, even if you think you’ll feel more tired in the morning then going all in on the 24h no sleep train. (You can also check our article about sleep deprivation to find out more about that.)
Wearing shades on bright sunny days. Yes, they are not just for looks. Most shades block around 95% of the UV light that hits your eye. (Just remember to take them off when you are inside.)
If you’re staring at a screen all day glasses can also help reduce strain on your eyes, especially if they have a blue or a green filter. Remember to give your eyes a rest. If you are staring at a monitor/screen or concentrate on reading that favorite book that you have, take a few minutes looking at something else. This helps the eyes relax for a moment before going back to the task at hand.

You need to appreciate what you have.


After all, the human eye is billions of years in the making, and without them we can’t really experience the world’s beauty.


Story Source

The post above was made from the following materials:
Human eye | Wikipedia
X & Y Chromosomes | Wikipedia
Rods and Cones | Ask a biologist
Glaucoma | National Eye Institute
Cataracts | All about vision
Macular Degeneration | American Academy of Ophthalmology

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