Eye, vision defects

• What are the main parts of the eye that need to be learned?

  • Sclera
  • Cornea
  • Iris
  • Pupil
  • Lens
  • Retina
  • Ciliary muscles
  • Suspensory ligaments
  • Optic nerve
• What is the function of the sclera?


  It is the tough, supporting wall of the eye
• What is the role of the cornea?


  It is the transparent outer layer that bends light into the eye
• How does the iris function in relation to light?


  It controls the diameter of the pupil to regulate light entry
• What does the lens do in the eye?


  It focuses light onto the retina
• What is the function of the retina?


  It contains receptor cells sensitive to light intensity and color
• What controls the shape of the lens?

  The ciliary muscles and suspensory ligaments
• What is the role of the optic nerve?


  It transmits impulses from the retina to the brain
• What happens to the pupil in very bright light?


  • The pupil becomes smaller
  • Circular muscles in the iris contract
  • Radial muscles relax
• What occurs in dim light regarding the pupil?


  • The pupil becomes larger
  • Radial muscles contract
  • Circular muscles relax
• What is accommodation in the eye?


  • The process of changing the shape of the lens
  • Allows focusing on near and distant objects
• How does the eye focus on near objects?

  1. Ciliary muscles contract
  2. Suspensory ligaments relax
  3. Lens becomes fat (more curved)
  4. Increases light refraction
• How does the eye focus on distant objects?

  1. Ciliary muscles relax
  2. Suspensory ligaments tighten
  3. Lens becomes thin (less curved)
  4. Decreases light refraction
• What happens to the lens as a person gets older?


  It loses elasticity, making it harder to focus on near objects
• What is short-sightedness and long-sightedness related to?


  • Short-sightedness: lens cannot refract light correctly for distant objects
  • Long-sightedness: lens cannot refract light correctly for near objects
• What is the main purpose of the iris reflex?


  To protect the retina from very bright light
• What is the medical term for long-sightedness?

  Hyperopia
• What causes long-sightedness?


  It occurs when the lens is the wrong shape or the eyeball is too short
• How can long-sightedness be corrected?


  By using glasses with a convex lens
• What is the medical term for short-sightedness?

  Myopia
• What causes short-sightedness?


  It occurs when the lens is the wrong shape or the eyeball is too long
• How can short-sightedness be corrected?


  By using glasses with a concave lens
• What are the main types of contact lenses?

  • Hard lenses
  • Soft lenses
• Why are contact lenses popular?

  They are lightweight and almost invisible
• What is a disadvantage of soft contact lenses?

  They carry a higher risk of eye infections
• How does laser eye surgery correct vision?

  It vaporizes tissue to change the shape of the cornea
• What is the difference in effect between slimming down the cornea and making it more powerful during laser eye surgery?

  Slimming down improves short sight, while making it more powerful improves long sight
• What are the risks associated with laser eye surgery?

  Complications such as infection or worsened vision
• What is replacement lens surgery?

  It involves removing the natural lens and inserting an artificial lens
• What are the risks of replacement lens surgery compared to laser eye surgery?

  It carries higher risks, including possible damage to the retina
• What are the advantages and disadvantages of glasses for vision correction?


  Advantages:

  • Easy to use
  • Non-invasive

  
  

  Disadvantages:

  • Can be cumbersome
  • May not be suitable for all activities