THE EYE

THE EYE

focusing an object
1. the eye's able to focus on objects between the near point and far point the near point of a human eye is 25cm and the far point is infinity
  1. when focussing on close objects the ciliary muscles contract and the lens becomes thicker causing greater refraction of the light
    1. when focussing on a distant object the ciliary muscles relax and the lens becomes thinner causing less refraction of the light
Structure of the eye
1. light enters the eye through the transparent cornea which refracts light
  1. the light then passes through the pupil (gap in the iris)
    1. the iris can change the size of the pupil to decide the amount of light entering the eye
      1. the lens then further refracts the light so that it's focussed on the retina
        the retina then detects the light and sends signals down the optic nerve to be interpreted by the brain
        a camera works similarly, see "visible light" mindmap
Eye defects
1. short sightedness: can be caused by the eyeball being to long or the lens being unable to focus short sighted people are unable to focus on distant objects
2. Long sightedness: can be caused by the eyeball being too short or lens being unable to focus long sighted people are unable to focus on near objects
3. long and short sightedness can be treated by.......
  1. glasses and contact lenses: the artificial lenses refract the light before it enters the eye causing light to be focussed on the retina
  2. Laser surgery: the laser re-shapes the cornea causing the light entering the eye to refract differently focussing it onto the retina

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	Erstellt von Jack Willepotte vor fast 9 Jahre