The eye and correcting vision defects

• What does happen in the eye to look at near object?

  The ciliary musles contract and are tighten, it slackens the suspensory ligaments and it relaxes. The lens becomes more curved and this increases the amount by which it refracts light
• What does happen to an eye to look at distant objects?

  The ciliary muscles relax, which allows the suspensory ligaments to pull tight. This makes the lens go thin (less curved). So it refracts light by a smaller amount
• Who are the long-sighted people?


  People which are unable to focus on near objects
• How does long-sighted vision occurs?


  When the lens is the wrong shape and doesn`t refract the light enough or the eyeball is too short
• What does happen on the long sighted vision?


  The images of near objects are brought into focus behind the retina
• What is a cure for long-sighted vision?

  Glasses with convex lens
• What is a medical term for long-sightedness?

  Hyperopia
• Who are the short-sighted people?


  People which are unable to focus on distant objects
• When does this occur?

  When the lens is the wrong shape and refracts the light too much or the eyeball is too long
• What does happen in the short-sightedness?


  The images of distant object are brought into focus in front of the retina
• What is a cure for long-sightedness?


  Glasses with concave lens
• What is a medical term for short-sightedness?


  Myopia
• What are the contact lenses?


  Thin lenses that sit on the surface of the eye and are shaped to compensate for the fault in focusing
• Why are contact lenses popular?


  They are lightweight and almost invisible. More convenient.
• What are the two types of contact lenses?


  Hard lenses and soft lenses
• What is the difference between hard lenses and soft lenses?


  Soft lenses are more comfortable, but carry a higher risk of eye infections
• How does a laser eye surgeon can be used?


  Vaporise tissue, changing the shpae of cornea (changing how strongly it refracts light into the eye)
• What does slimming down do?


  Make it less powerful and can improve short sight
• What does changing the shape do?


  Makes it more powerful so will improve long sight
• How can long-sightedness be treated more effectively?


  By replacement lens surgery
• What does replacement lens surgery take?


  The natural lens of the eye is removed and an artificial lens made of clear plastic is inserted
• What does carry the highest risk of eye infection?

  Replacement lens surgery