2.87 - Eye response/focus

2.87 understand the function of the eye in focusing near and distant objects, and in responding to changes in light intensity

• Most of the bending of the light rays is done by the curved cornea but the lens can also bend the light rays but only slightly (focus)
• The shape of the lens is controlled by the ciliary muscles
• If you are looking at a distant object:
• The ciliary muscles relax
• This tightens the ligaments
• therefore the lens is pulled into a thin shape
• The distant object focuses on the retina
• If you are looking at a close object:
  • The ciliary muscles contract
  • This slackens the ligaments
  • therefore the lens becomes thicker
  • The near object focuses on the retina