Memory Anchor:

• Super Challenge:

  Stretch:

  Challenge:

Key Questions:

1. How do the cilliary muscles and the suspensory ligaments allow the eye to focus on near or distant objects?
   • The cilliary muslces Adjust the shape of the lens to make it more or less curved, so as to increase or decrease the refraction of light and the suspensory ligaments Slacken or stretch as the ciliary muscles contract or relax, to adjust the thickness and curvature of the lens. This in turn allows differences in the refraction of light onto the retina and therefore allows the eye to focus.
2. How is the eye adapted to its function?
   • The eye is a sense organ containing receptors sensitive to light intensity and colour.
3. How are the structures of the following related to their functions: - retina - optic nerve - sclera - cornea - iris - ciliary muscles - suspensory ligaments?
   • Retina - contains the photo receptors to allow us to see. Optic nerve - Transmits signals from the photo receptors to the CNS through being a nerve Cell. Sclera - Relatively tough outer casing of the eye for protection. Cornea - Transparent layer to allow light in. IT is curved to refract light. Iris - made of muscle to alter the amount of light entering the eye. Ciliary muscles - made of muscular tissue which contract or relax to move the suspensory ligaments. Suspensory ligaments - attached to the ciliary muscles and lens to aid accommodation.
4. What is accommodation?
   • Accommodation is the process of changing the shape of the lens to focus on near or distant objects.
5. What processes must the eye go through in order to focus on a near object or on a distant object?
   • To focus on a near object the eye must do the following: 1. The ciliary muscles contract. 2. The suspensory ligaments loosen. 3. The lens is then thicker and refracts light rays strongly. To focus on a distant object: - The ciliary muscles relax. - The suspensory ligaments are pulled tight - The lens is then pulled thin and only slightly refracts light rays.
6. What are myopia and hyperopia and how do they affect the eye?
   • Myopia is short sightedness and hyperopia is long sightedness and this causes rays of light to not focus on the retina.
7. What are myopia and hyperopia usually treated with and how do they help?
   • Generally these defects are treated with spectacle lenses which refract the light rays so that they do focus on the retina.
8. What new technologies are there in place to treat eye defects?
   • New technologies now include hard and soft contact lenses, laser surgery to change the shape of the cornea and a replacement lens in the eye.