May 12, 2021

Human Eye Structure and Function PDF

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Human eye structure and function PDF- Hello Aspirants, welcome to our site Today, we are providing you human eye Short notes PDF which helps you to understand this topic for competitive exams.

About Human Eye:

  • The human eye is one of five sense organs which is the most valuable and sensitive.
  • It helps us to see the wonderful surroundings and the colors around us.
  • The eyeball is approximately spherical in shape with a diameter of about 2.3 cm to 2.5 cm.
  • Refraction of the light rays entering the eye mostly occurs at the outer surface of the cornea.
  • The crystalline convex lens in eye merely provides the finer adjustment of focal length required to focus.

Parts Of human Eye:

  1. Cornea: The transparent spherical membrane covering the front of the eye.
  2. Iris: The colored diaphragm between the cornea and lens.
  3. Pupil: The small hole in the iris.
  4. Eye lens: It is a transparent lens made of jelly-like material.
  5. Ciliary muscles: These muscles hold the lens in position.
  6. Retina: The back surface of the eye.
  7. Blindspot: The point at which the optic nerve leaves the eye. An image formed at this point is not sent to the brain.
  8. Aqueous humour: A clear liquid region between the cornea and the lens.
  9. Vitreous humour: The space between the eye lens and retina is filled with another liquid called the vitreous humour.


  • The ability to focus both near and distant objects, by adjusting its  focal length, is called the accommodation Power of the eye
  • It is the ability of the ciliary muscles to change the focal length of the eye lens, called accommodation.

Defects of the Eye:

  • Although the eye is one of the most remarkable organs in the body, it can have several abnormalities, which can often be corrected with eyeglasses, contact lenses, or surgery.
  • The various defects by which the human eye suffer are:
    • Hypermetropia or long-sightedness
    • Myopia or short-sightedness
    • Astigmatism
    • Presbyopia.

Near Point of the eye:

  • It is the smallest distance, at which the eye can see objects clearly and comfortably, is called the near point of the eye or the least distance of distinct vision.
  • For a young adult with normal vision, it is about 25 cm from the eye.

Far Point the eye:

  • The farthest point up to which a short-sighted eye can see clearly is called the far point of the eye.
  • For a normal eye, the far point is infinity.

Colour Blindness

  • The maximum numbers of light-sensitive cells contained in the retina of the eye are of two types: Rod cells and Cone cells.
  • Rod-shaped cells respond to brightness or intensity of light and Cone-shaped cells, which respond to the color of the light. Therefore, cone-shaped cells enable us to distinguish between different colors.
  • When a person cannot distinguish between different colors, he is said to be color blind though his vision may otherwise be normal.
  • Color blindness is a genetic disorder, which occurs by inheritance. So far, there is no cure for color blindness.

In short, we will say that this topic is very interesting and enhance our knowledge about the human eye. Therefore, we will be providing you human eye short notes PDF by that you can easily understand this topic.

Interested Candidates can download Biology Human Eye Notes PDF from the below available link.

Human eye structure and function PDF – Download Here

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