The Eye

Front 1

 Pupil:

Back 1

through which light enters the lens, controls amount of light that enters the eye

Front 2

 Cornea:

Back 2

Layer at front of the eye that focuses 2/3 of the light rays through refraction, also protects eye

Front 3

 Lens:

Back 3

refracts rays from cornea further, because has slightly higher refraction index

Front 4

 Iris:

Back 4

controls size of pupil

Front 5

 Aqueous humor:

Back 5

liquids that help eyeball maintain shape, also provides lens with nutrients

Front 6

 Sclera:

Back 6

tough, light-proof protective covering of eye

Front 7

 Retina:

Back 7

takes light, turning it into chemical energy which turns into nerve impulses sent through the optic nerve

Front 8

 Vitreous humor:

Back 8

liquid gel that helps eyeball maintain shape

Front 9

 Optic nerve:

Back 9

Sends signals to brain which interprets what you see

Front 10

Ciliary muscles:

Back 10

gives power to lens in order to focus eyes

Front 11

 Fovea:

Back 11

sensitive area responsible for sharp central vision

Front 12

1. Hyperopia (farsightedness):

Back 12

 Unable to see objects close up
 Caused by “short” eye
 Image forms behind retina so image blurry; focal length too large
 Convex lens (converging lens) used to decrease focal length

Front 13

2. Myopia (nearsightedness):

Back 13

 Unable to see objects far away
 Caused by eye that is “too long”
 Images form in front of retina (not on it) so images come out
blurry; focal length is not large enough
 Concave lens (diverging lens) used to increase focal length

Front 14

3. Presbyopia:

Back 14

 Eye cannot focus close up
 Ciliary muscles lose power and/or lens loses elasticity
 Convex lens glasses used to lessen focal length

Front 15

4. Astigmatism:

Back 15

 Caused by irregularly shaped cornea or lens, causing blurred vision
 Causes light to focus on different points in the back of eye
 Glasses that compensate for cornea’s weird shape

Front 16

Glaucoma

Back 16

 Optic nerve cells killed
 Causes blindness
 Fix with eye drops, drugs or laser eye