eye

• pupil

  hole which light can pass through
• iris


  coloured part of eye
• cornea


  at front of eye

  transparent which cover iris and pupil

  cause main focusing light on retina
• lens


  focuses light on retina
• optic nerve

  a nerve that takes impulses from retina to brain
• retina


  back of eye

  changes energy transferred by light to impulses

  has rods (respond to brightness) and cones (respond to colour)
• rods


  respond to brightness in retina
• cones


  responds to colour In retina
• short sightedness


  long eyeball so image focused in front/before retina

  correct with diverging lens spreads out rays
• long sightedness


  short eyeball image is focused behind retina

  converging lens bends light
• colour blindness


  can't be corrected

  cones don’t work properly can’t see certain colours like red and green
• cataract


  protein builds up in lens so it becomes cloudy

  corrected by removing lens with plastic lens
• muscles in iris


  control how much light enters

  size of pupil
• neurones carry impulses from…


  cones and rods to brain
• what light sensitive cells in retina respond to light


  cones and rods
• in short sightedness


  light hits before retina
• in long sightedness


  light hits after passing retina