The eye

• The iris controls the amount of light entering the eye through its pupil.
• The cornea refracts the light into the eye
• The iris contains muscle that control the size of the pupil, controlling how much enters the eye
• The pupil is the opening of the eye that allows light to enter the eye.
• The lens focuses light on the retina
• The retina is the light-sensitive layer at the back of the eye.
• The retina contains:

  Rod cells - sensitive at low light intensity

  Cone cells - sensitive to colour
• The optic nerve is the nerve that carries impulses from the retina to the brain
• The ciliary muscles and suspensory ligaments control the size and shape of the lens
• Short sightedness

  • Eyeball is too long
  • Cure - concave lens

  
• Concave lens - diverge light rays before entering eye
• Convex - converge light rays before entering eye