Correcting Vision Defects

• What is the term for not being able to focus on far away objects?

  Short-sighted
• What is the term for not being able to focus on nearby objects?

  Long-sighted
• How does long-sightedness occur?

  The lens is in the wrong shape and doesn't refract the light enough, or the eyeball is too short
• Where do images focus for long-sighted people?

  Behind the retina
• What type of lens is used to correct long-sightedness?

  Convex lens
• What is the medical term for long-sightedness?

  Hyperopia
• What is the medical term for short-sightedness?

  Myopia
• How does short-sightedness occur?

  The lens is in the wrong shape and refracts the light too much or the eyeball is too long
• Where do images focus for short-sighted people?

  In front of the retina
• What lens is used to correct short-sightedness?

  Concave lens
• What are treatments for vision defects?

  • Glasses
  • Contact lenses
  • Laser eye surgery
  • Replacement lens surgery
• What are the two types of contact lens?

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

  Soft lenses are more comfortable but carry a higher risk of infection
• How does laser eye surgery work?

  A laser vaporises tissue, changing the shape of the cornea
• How does replacement lens surgery work?

  The natural lens is removed and an artificial lens made of clear plastic is inserted