1. EYE
The eye is an extension of the brain

2. Eye brain proxomity
Can you see :
the optic nerve bundle?
Spinal cord?

3. Cross section You must know the position of: Retina Lens Cornea
Sclerotic
Optic nerve
Cilary muscles
Suspensory ligaments

5. Cornea: The clear, strong surface layer of the eye covering the iris and pupil.
The cornea is the first part of the eye that bends (or refracts) the light and provides most of the focusing power.

6. Conjunctiva: Is a membrane that covers the cornea and lines the inside of the eyelids. It helps lubricate the eye by producing mucus.

7. Sclera: Is the outside white of the eye which covers the entire eye apart from the front. It supports and protects the eye, serves as an attachment for the extrinsic eye muscles and aids in focusing.

8. Choroid: Is the second layer of the eye between the sclera and retina
Choroid: Is the second layer of the eye between the sclera and retina. It serves as additional protection and support for the eye. It is the blood-rich membrane that is responsible for supplying blood to the retina

9. Retina: The retina is the inner lining of the back of the eye that contains the visual cells (rods and cones). The function of the retina and visual cells is to convert light rays into electrical impulses that are transmitted to the brain by way of the optic nerve

10. Iris: The coloured muscular membrane which lies behind the cornea and in front of the lens.
Determines the size of the pupil and hence the amount of light entering the eye

11. Lens: A transparent biconvex disc made of protein
Lens: A transparent biconvex disc made of protein. It focuses the light on the retina

12. Changing lens thickness
The lens is slightly elastic, its relaxed state is short and fat.
Cilary muscles are attached to the lens, when contracted they pull the lens thin

13. Aqueous humor: Fluid that fills the anterior cavity
Aqueous humor: Fluid that fills the anterior cavity. It has small refractive power.
Vitreous humor: Fluid that fills the posterior cavity. It has small refractive power.

14. Ciliary Body: Is the muscle that holds the lens in place yet allows for flexible movement of the lens. It separates the posterior and anterior cavities.

15. Optic Nerve: Is attached to the retina and transmits visual signals to the visual cortex of the brain for processing.

16. Fovea: the concave centre of the retina
Fovea: the concave centre of the retina. The region of highest visual acuity and cone cell density

17. Retina – receives the image
Full of light receptors which are sensitive to:
Colour
Light levels
Massive blood supply is also needed
Fovea is the main focal point and has greatest density of light receptors

18. Retina receptors
Light receptors are called rods and cone

19. Focusing on objects
The lens and cornea focus the light on the retina

20. Focusing The lens job is to make the rays hit the same point
The red rays will be out of focus

21. Bending light
Light is refracted and bent to focus it as it passes through the lens
Lens thickness can be changed so the amount of bending is changed

22. Near vision
to bend the light more to focus it
Fat lens needed

23. Distance vision Rays enter the eye closer together Need less bending
Thinner lens needed

24. Controlling light levels
Your eye are very sensitive and can be damaged by harsh light.
Your iris controls light allowed into the eye by changing the size of the pupil

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