Eye

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Slide 1

EYE

The eye is an extension of the brain

Slide 2

Eye brain proxomity

Can you see :

the optic nerve bundle?

Spinal cord?

Slide 3

Cross section

You must know the position of:

Retina

Lens

Cornea

Sclerotic

Optic nerve

Cilary muscles

Suspensory ligaments

Slide 4

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

Slide 5

Retina receptors

Light receptors are called rods and cone

Slide 6

Focusing on objects

The lens and cornea focus the light on the retina

Slide 7

Focusing

The lens job is to make the rays hit the same point

The red rays will be out of focus

Slide 8

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

Slide 9

Near vision

to bend the light more to focus it

Fat lens needed

Slide 10

Distance vision

Rays enter the eye closer together

Need less bending

Thinner lens needed

Slide 11

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

Slide 12

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