Structure and Function of Human Eye

Humans have basically the 5 senses we say, Ear, eye, taste, touch and smell. All of them vision is the most complex, efficient, highly developed and important sense for humans and other creatures present in this world. Vision enables us to be aware of the changing environment and to adapt our behavior accordingly. With the help of microscope and telescope, vision helps us to probe the secrets of nature. We discuss the Anatomy of the Eye & Structure of Human Eye.

Human eye have its specific electromagnetic radiations, others animals can detect different range of electromagnetic radiations. For example, a rattle snake cans detect its prey by measure of infrared radiations, thus it can locate warm blooded animals in the dark.

Anatomy of the Eye

Structure and Function of Human Eye

Eyes are basically, the blessings of God. The human eye is often linked to the camera and the comparison is the convenient one. Movement of eye ball is necessary to prevent the eye from fatigue and maintain or visual field. Eye is the sensory organ that collects information that allows us to see the world. It is here that converted light energy into electrical signals.

See Also More: Structure of Ear

Many important structures are in the eye contributing the vision process.

  1. Sclera
  2. Choroid
  3. Retina
  4. Cornea
  5. Pupil
  6. Iris
  7. Lens
  8. Rods & Cones
  9. Vitreous Humor  
  10. Aqueous Humor
  11. Optic nerve
  12. The Blind spot
Eye Sclera

The outermost layer of our eye is called Sclera this is white, tough, dense, fibros layer it form the greater part of the outer layer of the eyeball, this is the window of the eye.

Second Layer

Eye Choroid

The second layer is choroid, its inner surface is dark brown and black, this has blood vessels and connective tissues in it, through these blood vessels eye have the source of food and nutrition, essential nutrients and minerals are provided by these blood vessels. The dark pigmentation is absent in albinos, who are almost in blind in bright daylight.   


Eye Cornea

Without eyes we cannot enjoy the beauty of world, eyes are the source of communicating to the world. Our eyes are responsible for all the information we receive. Object reflected the light and that light enter in our eyes and we can see that object. The first exposure of light is with the Cornea; light enter into the eye through it. This is protection shield of eye this prevent eye from external damage and dust.


Eye Iris and Pupil

The amount of light entering the eye is controlled by the pupil (this is hallow space in the eye in dark light the size of pupil becomes large), who is surrounded by the iris; iris is the responsible of the color of your eyes as, green, blue, and hazel.

Eye Lens

Eye Lens

After passing thorough the Pupil, light enter into the lens, a transparent elastic structure that focus light on the back of eye by changing its shape. This focusing process is called accommodations. The lens helps to focus light on the retina. It can do this because it is adjustable, and uses a muscle called the ciliary muscle to change shape and help us focus on objects at different distances. The automatic focusing of the lens is a reflex response and is not controlled by the brain. 

Eye Retina

Eye Retina

Lights bends because the front part of the eye is curved, this bending light make an image at Retina (The part of eye responsible for the image creation, we can see image through retina) it actually create upside down image this is the responsibility of the brain to turns it right way up. Retina is very complex and sensitive part of eye; its main function is to turns light into electrical signals that brain can interpret. This interpretation of brain actually makes the image recognizable. Retina is packed with photosensitive cells called rods and cones.

Eye Cones

Eye Cones

Cones are the cells responsible for daylight vision. There are three kinds, each responding to a different wavelength of light: red, green and blue. The cones enable us to see images in color and detail. Rods are responsible for night vision. They are sensitive to light but not to color. In darkness, the cones do not function at all.

Vitreous Humor

Eye Vitreous Humor

Aqueous Humor is the fluid filled around the lens to prevent lens from damage. Vitreous humor is the fluid filed in the eye that intact the shape of eye. The round shape and beauty of eye is to vitreous humor.

Optic Nerve  

Eye Optic Nerve  

Once the image is clearly focused on the sensitive part of the retina, energy in the light that makes up that image creates an electrical signal. Nerve impulses can then carry information about that image to the brain through the optic nerve.

Eye Blind spot

Eye Blind spot

The point where the optic nerve fibers leave the eye and enters into the brain the retina has no receptors, this is called the blind spot. This is very important as there is permanent hole in our visual field buy we normally no aware of it, the visual nervous systems somehow fills in this blind spot. Structure of the eye is the main and important part of human body.

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