Eye Anatomy and Physiology

Eye Anatomy and Physiology

The eye is the sensory organ of sight. It enables us to see, receive and sort out visual details. Only about one-sixth of the eyeball is visible. The remaining parts are covered by a protective coating of bones, muscles and fat.


The eye consists of 3 main parts:

  • eyeball
  • eye socket (orbit)
  • accessory structures

Anatomy & Physiology

Eye Anatomy and PhysiologyAll of the following parts work together to produce clear sight:

  1. The sclera- white part of the eye.
  2. The pupil- black hole at the center of the eye. Through this hole, light enters the eye.
  3. The iris- or colored part of the eye, located in the middle of the pupil. It regulates the light entering the eye by changing the size of the pupils.
  4. The cornea- a clear part at the front of the eye.It serves as a protective covering of the iris and the pupil. It allows the light to enter the eye.
  5. The lens- located behind the pupil, it focuses the light onto the retina.
  6. The retina- the inner lining at the back of the eye. Different cell layers detect light and switch it into electrical impulses.

How do we see?

The eye works in the same manner as a camera. It performs following routines so as to make images look clear and sharp.

  1. Light reflects off the shapes and objects we are monitoring
  2. Light rays enter the eye and it passes through the cornea
  3. The light passes through aqueous humor and enters the pupil
  4. The iris then fine-tunes the amount of light let into the eye
  5. The lens targets the light onto the retina and change in thickness to bend and refract the light rays. Now the light is translated into to a signal transmitted to the brain by the optic nerve.
  6. Upon receiving these signals/electrical impulses visual cortex of the brain transforms them into visual images.

Eye Anatomy and PhysiologySo, people and camera lenses both focus an image onto the photosensitive surface. On a camera, it’s focused on film or a sensor chip. When using our eyes, the light-sensitive surface is the retina on the inside of your eyeball. Also, both the eye and a camera can adjust the amount of light entering. On a camera, it’s performed with the aperture lens control, while in your eye, it’s done by the iris expansion and contraction.

Normal vision

Seeing clearly and sharply in the center of our surroundings, and blurry in the periphery is treated as normal vision.

Vision problems

Many types of eye conditions can cause eye problems and blurred vision. Depending on the severity of the condition eyesight can be corrected by eyeglasses, contact lenses, and in some cases surgery.


Regardless of being the smallest organs in the body, our eyes are the most important organs along with the brain. They perform one of the most valuable operations that people tend to rely on most- seeing.