The Human Eye Facts, Functions, Structure and Problems

The Eye Definition Biology:

The Human Eye FactsWhat do you know about the eye definition biology? Just learn about human eye facts and you will get precious information about it. You can define the eye as an organ of vision which makes you visualize the world around you. The eyes are two in number and each is placed inside specialized compartments in the skull.

The human eye is the organ which enables you to see. The human eye does not only let you view the scenes and phenomenon in your surroundings, but also enables you to differentiate between colors. Sometimes, there is a minor defect in the eye function and the individual cannot make difference between the red and green color. What is the name for such a condition? Well, you call it ‘color blindness’.

Human Eye Diagram:

No doubt, the human eye diagram will add a lot to your knowledge. But, it cannot give you all the interesting information about its working mechanism and capabilities.

Human Eye Diagram

When you talk of the human eye structure, they exist in pairs, each one being approximately 2.5 cm in diameter. There are following main parts of human eye:

  • Sclera: The knowledge of eye parts and functions is both useful and interesting. The white part of our eyes is known as sclera. It consists of fibrous tissues. The job of this part it to protect the internal parts of the eye.
  • Cornea: The transparent tissue through which light enters the eyes is called cornea. It exists in front of the eye. That is why, it looks prominent among different parts of the human eye.
  • Iris: Iris is made up of muscles which contract or relax in order to adjust the amount of light which enters the eye.
  • Pupil: There are many interesting facts about the pupil. It is, actually, an aperture controlled by the iris muscles. For instance, when it is dark, the iris muscles relax, causing the pupil to open up wider. Therefore, more light enters the eyes to enable us to see better. On the other hand, the pupil becomes narrow due to the contraction of the iris muscles. It occurs in the presence of excessive light in order to protect the cells of the eyes.
  • Lens: The lens is present behind the pupil. Light enters the pupil, passes through the lens and is focused on the retina of the eye. The lens is capable of changing its shape in order to help us see near or far off objects. This is about how the human eye works.
  • Retina: Digging further deeper into the human eye anatomy, you will come across the retina. The retina converts light into electrical signals which are transferred to the brain for processing. The retina contains two types of cells: rods and cones. These cells are sensitive to light. Rods are important for night-time vision when there is little light. On the other hand, cones play an important role in helping us see colors.
  • Optic Nerve: The optic nerve takes electrical signals from the retina of the eye to the brain.
  • Eye Function

    Eye function renders you the sense of sight. They convert light into electrical signals. Afterwards, the brain deciphers these electrical signals into images. Properly working healthy eyes are able to perform the following functions.

    • It is one of the important human eye facts that they help us view our surroundings.
    • Our eyes enable us to see colors. Certain organisms, such as dogs, cannot see colors and, so, their world is black and white.
    • Eyes help us see near as well as distant objects.

    Human Eye Facts – How It Works

    There is one of the human eye facts that these small organs perform a very complex function. The working mechanism of the eyes consists of the following simple steps.

    • When we see an object, light is reflected off it into our eyes.
    • The light rays entering our eyes first pass through the pupil. These are the muscles of iris that control the size of the pupil.
    • After passing through the pupil, light passes through the transparent lens of the eye. There occurs the refraction and focusing of the light rays on the retina.
    • Light sensitive cells, rods and cones, present in the retina covert the light rays into electrical impulses. Isn’t it one of the most amazing facts about eyes of human beings.
    • The optic nerve transfers these electrical impulses from the retina to the brain which then processes these signals and translates them in the form of an image.

    Eye Problems

    The Human Eye Problem ConjunctivitisThese extremely delicate organs can fall prey to different eye problems due to allergic factors, unhygienic conditions and the old age. Below are some of the most common diseases of eyes.

    Furthermore, the light is another factor that may cause damage to your eyes, regardless of whether it comes from a floor lamp, mobile phone, or any other source.


    Conjunctivitis has got a common name – the pink eye disease. It is an inflammation of conjunctiva, the transparent membrane which covers the sclera. Inflammation of tiny blood vessels found in conjunctiva makes our eyes appear red.


    The Human Eye Problem CataractCataracts affect the eye lenses. They may occur due to old age or exist as a defect by birth. Parts of lenses become opaque, blocking the passage of light to the retina, thereby obstructing our vision.


    Glaucoma is a disease which leads to blindness due to a damage to the optic nerve. When the optic nerve fails to transmit electric signals to the brain, an individual is unable to see at all.

    The Human Eye Problem GlaucomaFrom the above information, you can realize that eye is one of the greatest blessings of nature. The human eye facts reveal that it is very complex in terms of both structure and function. In the process of visualizing an object, the light rays fall on that object. After reflecting from there, they enter the eye. Passing through different parts of the eye, the light rays reach the retina. After that, there is conversion of light rays into electrical signals. The brain reads these signals and translates them into images of the objects. Don’t such human eye facts make you ponder about this marvelous creation of nature?

    Meanwhile, if you want your eyes to keep working at their best potential throughout your life, do take proper care of them. To maintain the health of eyes, you need to take all the essential nutrients for eyes in adequate quantity as well as avoid over-burdening them.

About the Author

Posted by: M. Isaac / Senior writer

A graduate in biological sciences and a PhD scholar (NCBA&E University, Lahore), M. Isaac combines his vast experience with a keen and critical eye to create practical and inherently engaging content on the human body. His background as a researcher and instructor at a secondary school enables him to best understand the needs of the beginner level learners and the amateur readers and educate them about how their body works, and how they can adopt a healthier lifestyle.

Copyrights Reserves 2013-2023 by