The Eye

• What is the sclera?


  The tough supporting wall of the eye
• What is the cornea?

  The transparent outer layer on the front of the eye
• What does the cornea do?

  It refracts light
• What does the iris do?

  Has muscles which control the diameter of the pupil and therefore how much light enters the eye
• What does the lens do?

  Focuses light onto the retina
• What does the retina contain?

  Receptor cells sensitive to light intensity and colour
• What controls the shape of the lens?

  Ciliary muscles and suspensory ligaments
• What does the optic nerve do?

  Carries impulses from the retina to the brain
• Where is the retina?

  On the inner layer of the eye at the back
• What is the iris reflex for?

  Stopping bright light from damaging the retina
• What happens in the eye when there is bright light?

  Muscles in the iris contract and radial muscles relax making the pupil smaller
• What happens inside the eye in dim light?

  Radial muscles contract and circular muscles relax making the pupil wider
• What changes shape to focus on near and far objects?

  The lens
• What is the term for changing the shape of the lens to focus on objects?

  Accommodation
• What happens in the eye when looking at nearby objects?

  • Ciliary muscles contract
  • Suspensory ligaments slacken
  • The lens becomes fat
  • The eye refracts light more
• What happens in the eye when looking at a far away object?

  • Ciliary muscles relax
  • Suspensory ligaments tighten
  • The lens becomes thin
  • The eye refracts light less