How do we see?

• How we see

  • light rays are refracted through the cornea and the aqueous humour onto the lens
  • the lens causes further refraction and the rays are brought to focus on the retina
  • image on the retina stimulates rods or cones to form an image
  • image is inverted, laterally inverted and diminished
• Focusing/accommodation


  • adjustment of lens of the eye so clear images of objects at different distances can be formed on the retina
• Focusing on a distant object


  • ciliary muscles relax and pull on suspensory ligament
  • suspensory ligament becomes taut, pulls on edge of lens more
  • lens becomes thinner and less convex
  • light rays from distant object refract less and are sharply focused on the retina
  • photoreceptors are stimulated
  • nerve impulses are produced and transmitted by the optic nerve to the brain
  • the brain interprets the nerve impulses and the persons sees the distant object

  
• Focusing on near objects

  ciliary muscles contract and pull less on suspensory ligament suspensory ligament slackens, pulls on edge of lens less lens becomes thicker and more convex light rays from distant object refract more and are sharply focused on the retina photoreceptors are stimulated nerve impulses are produced and transmitted by the optic nerve to the brain the brain interprets the nerve impulses and the persons sees the distant objectFocusing on a distant object