5.5 - Eyes (Accommodation and Visual Defects)

• Hyperopia


  Long-Sighted
• Myopia


  Short-Sighted
• Accommodation 


  A reflex that changes the refractive power of the lens using the ciliary muscles and suspensory ligaments
• Ciliary Muscles and Suspensory Ligaments control the shape of the lens
• Nearby Objects:

  • Ciliary Muscle contracts
  • Suspensory Ligaments slacken
  • Lens is short and fat
• Distant Objects:

  • Ciliary Muscle relaxes
  • Suspensory Ligament becomes taut
  • Lens is long and thin
• What does long sighted mean?

  The eye is unable to focus on nearby objects
• What does short sighted mean?

  The eye is unable to focus on distant objects
• Long-sightedness (Hyperopia) = Convex lens
• Short-sightedness (Myopia) = concave lens