The Eye

• It has receptors that are sensitive to light intensity and colour
• The eye

  A) ciliary muscle

  B) suspensory ligament

  C) iris

  D) pupil

  E) cornea

  F) lens

  G) optic nerve

  H) sclera

  I) retina

  
• The retina is where the light receptors are
• The optic nerve carries impulses from the eye to the brain
• The sclera is the tough white outer layer to protect the eye
• The cornea lets light into the eye and retracts light towards the retina
• The iris controls how much light enters the pupil
• The ciliary muscle and suspensory ligaments change the shape of the lens to focus the light on the retina
• Accommodation is the process of changing the shape of the lens to focus on near or distant objects
• Near objects - the ciliary muscles contracts and the ligaments loosen causing the lens to thicken and refract strongly
• Far objects - the ciliary muscles relax and the ligaments are pulled tight causing the lens to be pulled thin and only slightly refract light
• Myopia - short sightedness, can see near objects clearly but far objects, the light is focused in front of the retina. Need a concave lens
• Hyperopia - long sightedness, can see far objects clearly but near objects, the light is focused behind the retina. Need a convex lens
• Eye problems can be treated with glasses, contact lenses or laser eye surgery