1. 25 / Monday
Kaupapa:
Draw and label a diagram showing the structure of eye
Describe the functions of different parts of eye

2. Do you remember?
What are the three things that can happen when radiation hits a surface?
What is “refraction”?
What is “total internal reflection”
Give an example of when total internal reflection is useful

3. The Eye

4. Question:
How do we “see” things?

5. Eyes = “Light detectors”

8. How we “see” things:
When we are seeing an object, our eyes are being exposed to the light that is coming from the object.
Luminous objects produce light (e.g. the sun), whereas other objects reflect light so we can still see them (e.g. the moon).

9. The Structure of Eye cornea sclera (white coat) iris lens retina pupil
optic nerve

10. Iris (and Pupil)

12. Iris
Pupil

13. Iris and Pupil
“In dark”
“In light”
When it’s dark, the Iris opens up and the pupil (the opening) gets larger, so more light can come through the eye.

16. Lens
The lens focuses the incoming light so a clear image can be produced on the retina.

18. Normal Eye

19. Myopia (Short sightedness)

21. Retina. Ophthalmoscope image of a healthy retina (orange)
Retina. Ophthalmoscope image of a healthy retina (orange). The blood vessels on the retina are visible through the pupil of the eye. The retina is the light-sensitive membrane at the back of the eye. The pupil is surrounded by the iris (blue), a ring of muscle that contracts or relaxes to alter the amount of light entering the eye. Ophthalmoscope views of the retina can be used to diagnose a range of disorders, including glaucoma, retinal detachment and retinal cancer.
Retina

23. Retina rod cells. Coloured scanning electron micrograph (SEM) of a freeze-fractured section through a retina, revealing the structure of its photoreceptors. Photoreceptors with these rod-like outer parts (green) are named rod cells (rather than cone cells) and contain the protein rhodopsin (visual purple) that aids vision in dim light. The inner parts (orange) lead to the nuclei (blue/red, top). Empty spaces in this layer show Muller cells that provide a fibrous support for photoreceptors. Light triggers signals in the photoreceptors after passing through a neuron layer (above nuclei, not seen). These signals travel to the neurons and on to the brain. Magnification: x3000 at 6x7cm size.

24. Retina
It is the area on the back of the eye covered with photoreceptors which turns the focused image into an electrical signal.
The signal is sent to the brain via the optic nerve.

25. What have we learnt today?