the eye

Question 1

What happens to the pupil in bright light?

Answer 1

1. Light receptors detect bright light.
2. A reflex is triggered making the pupil smaller.
3. Circular muscles in the iris contract.
4. Radial muscles relax, reducing light entry.

Question 2

What occurs in dim light regarding the pupil?

Answer 2

1. Radial muscles contract.
2. Circular muscles relax.
3. The pupil widens to allow more light in.

Question 3

accommodation

Answer 3

the process of changing the shape of the lens to focus on near or distant objects

Question 4

sclera

Answer 4

tough, supporting wall

Question 5

cornea what is it + function?

Answer 5

• transparent outer layer found at the front of the eye
• refracts light into the eye

Question 6

iris what does it contain + function

Answer 6

• contains muscles to control the diameter of pupil
• control how much light goes in

Question 7

lens what does it do

Answer 7

• focuses light onto retina

Question 8

optic nerve function

Answer 8

• carries impulses from the receptors on the retina to the brain

Question 9

what does the retina contain?

Answer 9

receptor cells sensitive to light intensity and colour

Question 10

what is the shape of the lens controlled by?

Answer 10

ciliary muscles and suspensory ligaments

Question 11

what type of organ is the eye?

Answer 11

a sense organ

Question 12

what happens to focus on a near object?

Answer 12

• the ciliary muscles contract
• the suspensory ligaments loosen
• the lens is then thicker and refracts light rays strongly

Question 13

what happens to focus on a distant object?

Answer 13

• the ciliary muscles relax
• the suspensory ligaments are pulled tight
• the lens is then pulled thin and only slightly refracts light rays.

Question 14

myopia

Answer 14

short-sightedness, can’t focus on distant objects

Question 15

hyperopia

Answer 15

long-sightedness, can’t focus on near objects

Question 16

why do myopia and hyperopia occur?

Answer 16

rays of light don’t focus on the
retina

Question 17

why does long-sightedness occur?

Answer 17

• lens is the wrong and doesn’t refract the light enough
• eyeball is too short
• so refracted rays focus after retina

Question 18

where are the images of near objects brought into focus?

Answer 18

behind the retina

Question 19

which lens can correct hyperopia and why, how?

Answer 19

convex, curves outwards, lens refracts light rays to focus on retina

Question 20

why does short-sightedness occur?

Answer 20

lens is wrong shape and refracts too much light, or eyeball is too long

Question 21

where are the images of distant objects brought into focus?

Answer 21

in front of retina

Question 22

which lens can correct myopia and why, how?

Answer 22

concave, curves inwards, light rays focus on retina

Question 23

what are the lenses most commonly used called?

Answer 23

spectacle

Question 24

list 3 new technologies for treating vision defects

Answer 24

• contact lenses
• laser eye surgery
• replacement eye surgery

Question 25

two types of contacts, pros/cons

Answer 25

hard - less comfy, lower risk of infection soft - more comfortable, higher risk of infection

Question 26

pros of contact lenses

Answer 26

lightweight, convenient

Question 27

laser eye process

Answer 27

laser used to vaporise tissue, changing shape of cornea

Question 28

what does slimming cornea down do?

Answer 28

make it less powerful, improve short sight

Question 29

what does thickening cornea do?

Answer 29

make it more powerful, improve long sight

Question 30

how does replacement lens work?

Answer 30

natural lens is removed and artificial lens made of plastic inserted in its place