the eye

• what happens to the eye when focusing on a nearer object ?

  ciliary muscles contract

  suspensory ligaments loosen

  lens becomes thicker and refracts more strongly
• what happens to the eye when focusing on a distant object?

  ciliary muscles relax

  suspensory ligaments are pulled tight

  lens is pulled thin and only slightly refracts light rays
• how do muscles in the iris help a person move from a dimly-lit area to a brightly-lit area?

  muscles in the iris contract to reduce the size of the pupil
• what does the iris do

  controls the size of the pupil
• what does the pupil do?


  allows light to enter the eye
• what does the cornea do?

  refracts light onto the lens
• what does the lens do?

  refracts light onto the retina
• what does the retina contain?

  photo receptors which receive the signals and pass them onto the brain via the optic nerve
• myopia is 


  short sighted [ image is in the middle of the eye ]
• hyperopia is


  long sighted [ image is behind eye]
• myopia can be fixed by a

  concave lens
• hyperopia can be fixed by a

  convex lens
• what is accommodation?

  the process of the lens changing shape to focus on an object as its distance from the eye changes. this is done by the ciliary muscles and suspensory ligaments