Monday, 6 February 2012

2.87 Eye Reponse

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 lenses can also bend light slightly. The shape of the lens is controlled by the ciliary muscles.

When you are looking at a far object:

  • The ciliary muscles relax
  • Which tightens the suspensory ligaments
  • The lens turn into a thin shape
  • The distant object is focused on the retina
When you are looking at a close object:
  • The ciliary muscles contract
  • This slackens the suspensory ligaments
  • Elastic lens becomes fatter
  • The near object is focused on retina
image courtesy of michelle biology

If there is bright light:
  • Circular muscles contract
  • Radial muscles relax
  • Pupils become smaller and less light enters the damage (to decrease damage that can be caused by strong light intensity)
If there is dim light:
  • Circular muscles relax
  • Radial muscles contract
  • Pupil enlarges and more light can enter the eyes, which helps us see in dark places

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