Chapter 6 extra Flashcards Preview

Science 8 > Chapter 6 extra > Flashcards

Flashcards in Chapter 6 extra Deck (51):
1

What is vision?

Vision is how we see

2

What is weird about how we see?

Vision uses our brains much more than our eye balls

3

Where does light energy enter the eye?

Light energy enters the eye via the cornea

4

Where does light pass through?

Light passes through the pupil

5

What can the pupil do?

The pupil can expand and contract

6

Why does the pupil expand and contract?

The pupil expands and contracts to adjust the amount of light entering the eye

7

What helps focus the image?

the lens helps to focus the image

8

Where does light finally hit?

The light finally hits the retina at the back of the eye.

9

What does the retina have?

The retina has two types of cells: Cones and Rods

10

What are cone cells?

Cone cells are heavily involved in colour vision.

11

Where are cones found?

Cones are found in the area called the fovea, which is the center of the retina

12

Where is the fovea?

The fovea is in the center of the retina

13

When the viewer is looking directly at something, where does the image land on the back of the eye?

The image lands on the fovea when someone is looking at something directly

14

What are rods for?

Rods are important for black and white viewing.

15

Where are rods found?

Rods are mostly at the edge of the retina

16

Where does information from the rods and cones go?

The rods and cones send information through the optic nerves

17

What is the optic chiasm?

The optic chiasm is where the optic nerves cross before the enter the brain.

18

Why do the optic nerves cross?

The optic nerves cross so that the brain gets information from both eyes

19

Where does the information travel after the optic chiasm?

Lateral Geniculate nucleus (LGN) to the primary visual cortext (V1) and then to the occipital lobe

20

What happens to the image when it enters the eye?

Because it is a reflection it is flipped upside down and reversed, so the brain has to put it the right way up.

21

What is the first thing the brain does?

The first thing the brain does is to flip the image upright and from right to left

22

What does the occipital lobe do?

The occipital lobe processes the correct information

23

What is perception?

Perception is when you become aware of the image that has entered your brain.

24

What is myopia?

Myopia is near-sightedness.

25

What is near-sightedness?

you are able to focus on close objects but distant objects are out of focus... ie you need glasses to drive or see the board but not to read

26

How does myopia happen?

When light enters the eye and it converges (meets) at a point in front of the retina instead of on the retina

27

What shape is the eye if you have myopia?

The eye is too long front to back – axial myopia

28

What shape is the refractive tissue (the cornea and lens) if you have myopia?

If you have myopia you cornea and lens are too high, which causes the image to focus in front of the retina, which makes distant objects blurry

29

Who is an optometrist?

An optometrist is a person who measures your eyesight and prescribes glasses.

30

What are corrective lenses?

Corrective lenses are lenses that go into glasses to fix bad vision

31

How is myopia corrected?

Myopia is corrected with concave glasses lenses

32

How do concave lenses help?

Concave lenses diverge (spread out) the light and push the focal point further back onto the retina

33

What is hyperopia?

hyperopia is far-sightedness

34

What is far-sightedness

far sightedness or hyperopia is when near objects are out of focus, so you can see well to drive or see the board but you can't see the words to read a book.

35

What happens to the light in hyperopia or far-sightedness?

In far-sightedness the light converges (meets) at a focal point behind the retina, so objects are out of focus

36

What is wrong with the eye that you get hyperopia?

Hyperopia or far-sightedness is caused by the eye being too short or the power of the refractive tissue being too low

37

If you have extreme hyperopia what happens?

IN extreme cases of hyperopia, everything is blurry

38

How is hyperopia fixed?

Hyperopia or far-sightedness is corrected with a refractive lens

39

What is the lens shape that fixes far-sightedness?

A convex lens is for far-sightedness

40

How does a convex lens change the light rays?

A convex lens changes the light rays by converging them (bringing them together) and pulls it further forward onto the retina.

41

What is presbyopia?

Presbyopia is the deterioration of the eye as you age.

42

Is presbyopia an illness?

No presbyopia is a natural part of aging.

43

What happens in presbyopia?

it becomes increasingly difficult to see images up close, in dim light and if there is sharp detail

44

How does this lack of focus happen?

The crystalline lens just behind the surface of your eye starts to harden and is less flexible

45

What happens when the lens isn't flexible?

When the lens loses its flexibility, you cannot focus your eyes as well

46

How can presbyopia be fixed?

Convex lenses fix presbyopia

47

What is the purpose of contact lenses?

Contact lenses replace glasses and correct vision.

48

What is laser eye surgery?

Laser eye surgery reshapes the cornea of the eye (the clear window that light passes through)

49

What cuts the cornea?

Instead of scalpel (knife) the surgeon uses a laser

50

What is a laser?

A laser is a device that emits (gives off) amplified light (light that has more energy)

51

How is the laser beam used?

The laser vaporizes (turns from liquid to gas) the soft tissue of the eye's cornea