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16 Cards in this Set

  • Front
  • Back
 Pupil:
through which light enters the lens, controls amount of light that enters the eye
 Cornea:
Layer at front of the eye that focuses 2/3 of the light rays through refraction, also protects eye
 Lens:
refracts rays from cornea further, because has slightly higher refraction index
 Iris:
controls size of pupil
 Aqueous humor:
liquids that help eyeball maintain shape, also provides lens with nutrients
 Sclera:
tough, light-proof protective covering of eye
 Retina:
takes light, turning it into chemical energy which turns into nerve impulses sent through the optic nerve
 Vitreous humor:
liquid gel that helps eyeball maintain shape
 Optic nerve:
Sends signals to brain which interprets what you see
Ciliary muscles:
gives power to lens in order to focus eyes
 Fovea:
sensitive area responsible for sharp central vision
1. Hyperopia (farsightedness):
 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
2. Myopia (nearsightedness):
 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
3. Presbyopia:
 Eye cannot focus close up
 Ciliary muscles lose power and/or lens loses elasticity
 Convex lens glasses used to lessen focal length
4. Astigmatism:
 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
 Optic nerve cells killed
 Causes blindness
 Fix with eye drops, drugs or laser eye