The Eye: Structure and how it works

By: Joe Denmark

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A Journey Through the Human Eye: How We See

Parts of the eye:

  • Iris
  • Retina
  • Fovea
  • Optic nerve
  • Cornea
  • Conjunctiva
  • Lens
  • Pupil
  • Ciliary muscle
  • Suspensory ligament

HOW IT WORKS

Images and information on how the human eye works
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Information On How The Eye Works

Vision begins when light rays are reflected off a surface or an object and enter the eye while passing through into the cornea, the part of the eye that you can't see that is the most outer part of the eye. The cornea bends or refracts the rays that pass through a round hole called the pupil. The iris, or coloured portion of the eye that surrounds the pupil, opens and closes (making the pupil bigger or smaller) to regulate the amount of light passing through. The light rays then pass through the lens, which actually changes shape so it can further bend the rays and focus them on the retina at the back of the eye. The retina is a thin layer of tissue at the back of the eye that contains millions of tiny light-sensing nerve cells called rods and cones, which are named for their distinct shapes. Cones are concentrated in the centre of the retina, in an area called the macula. In bright light conditions, cones provide clear, sharp central vision and detect colours and fine details. Rods are located outside the macula and extend all the way to the outer edge of the retina. They provide peripheral or side vision. Rods also allow the eyes to detect motion and help us see in dim light and at night. These cells in the retina convert the light into electrical impulses. The optic nerve sends these impulses to the brain where an image is produced and turned the right way up.