Chapter 9 - The Eye

Question 1

1. Define ‘Accommodation’ in respect of vision.

Answer 1

1. The changing shape of the lens as it focuses on near and distant objects, facilitated by the ciliary muscles.

Question 2

What is the ‘Iris reflex’?

Answer 2

The iris changing size according to available light.

Question 3

What is the iris/pupil configuration in:
A. Low light
B. Bright light

Answer 3

A. Large pupil, narrow iris (iris contracts)

B. Small pupil, wide iris (iris relaxes)

Question 4

What is ‘focal length’?

Answer 4

The distance between the lens and the focal point.

Question 5

1. What is a convex (converging) lens used to correct?

2. What is a concave (diverging) lens used to correct?

Answer 5

1. Long-sightedness

2. Short-sightedness.

Question 6

1. Describe the function of the cornea.

2. Describe the adaptations of the cornea.

Answer 6

1. Protects eye surfaces, and focuses light rays.

2. Is clear, colourless and curved.

Question 7

1. Describe the function of the lens.

2. Describe the adaptations of the lens.

Answer 7

1. Focuses light onto the retina.

2. Is clear, colourless, curved, and can change shape.

Question 8

1. Describe the function of the retina.

2. Describe the adaptations of the retina.

Answer 8

1. Detects light waves and produces impulses.

2. Contains rod cells, cone cells, and sensory neurones.

Question 9

1. Describe the function of the iris.

2. Describe the adaptations of the iris.

Answer 9

1. Controls pupil size, and regulates amount of light entering the eye.
2. Contains muscles.

Question 10

1. What is long-sightedness?

2. What is short-sightedness?

Answer 10

1. When close objects are blurry.

2. When far objects are blurry.

Question 11

1. What is long-sightedness caused by?

2. What is short-sightedness caused by?

Answer 11

1. An eyeball that is too short, or the cornea isn’t curved enough.
2. An eyeball that is too long, or the cornea is too curved.

Question 12

1. What cells in the retina cause colour blindness?

Answer 12

2. Cones.

Question 13

1. Name the eye problem that can be fixed by replacing the lens.

Answer 13

1. Cataracts.

Question 14

What muscles operate the lens?

Answer 14

Ciliary muscles.

Question 15

What cells detect low levels of light?

Answer 15

Rods

Question 16

What cells detect colour?

Answer 16

Cones.

Question 17

What causes the pupil to dilate and constrict?

Answer 17

Iris muscles.

Question 18

Why is it necessary for the iris muscles to cause the pupil to construct and dilate?

Answer 18

To control how much light enters the eye in order to protect the retina.

Question 19

In which order does light reach the parts of the eye?

Answer 19

1. Cornea
2. Pupil
3. Lens
4. Retina

Question 20

Can short-sightedness be corrected with surgery?

Answer 20

Yes

Question 21

Can long-sightedness be corrected with surgery?

Answer 21

Yes

Question 22

Can colour blindness be corrected with surgery?

Answer 22

No

Question 23

Can cataracts be corrected with surgery?

Answer 23

Yes

Question 24

How are cataracts corrected?

Answer 24

By removing the lens and replacing it with a plastic one.

Question 25

How is long/short-sightedness corrected?

Answer 25

By using lasers to reshape the cornea.

Question 26

What is the function of the optic nerve?

Answer 26

To transmit impulses to the brain.

Question 27

Where is the blind spot in the eye?

Answer 27

Where the optic nerve attaches to the eye.

Question 28

What is contained within the fovea?

Answer 28

Lots of cone receptors that give the best visual acuity.

Question 29

What is the medical name for long-sightedness?

Answer 29

Metropia

Question 30

What is the medical name for short-sightedness?

Answer 30

Myopia

Question 31

What causes colour blindness?

Answer 31

It is a genetic defect primarily affecting boys that is passed to them by their mother.

Question 32

What is the medical name for colour blindness?

Answer 32

Deuteranomoly

Question 33

What are cataracts?

Answer 33

Damaged lens proteins that cause the lens to become cloudy.

Question 34

What causes cataracts?

Answer 34

Dietary deficiency and long-term exposure to bright sunlight.

Question 35

Where do rods and cones send signals?

Answer 35

Down the optic nerve to the visual area at the back of the cerebrum.