Vision

Question 1

Where is the eye located?

Answer 1

In the bony socket so eye doesn’t pop out?

Question 2

What is the inner layer of the eye called?

Answer 2

Lens

Question 3

What is the role of the Iris?

Answer 3

This part lets light into the eye?

Question 4

What is the coloured part of the eye called?

Answer 4

Iris

Question 5

What is the role of the lens?

Answer 5

Located behind the iris, it is responsible for contracting and relaxing thus changing its focal point.

Question 6

How do the lens contract and relax?

Answer 6

Using ciliary muscles, they pull the lens to open and close.

Question 7

Where rods and cones located?

Answer 7

Retina and fomia

Question 8

What does the retina consist of?

Answer 8

Rods and cones. They detect light and colour.

Question 9

What does the term accommodation mean?

Answer 9

It means the opening and closing of the lens using ciliary muscles according to what the eye is trying to focus on.

Question 10

How much refraction does the cornea do?

Answer 10

70%

Question 11

What is the cornea?

Answer 11

The cornea is the transparent part of the eye covering the iris and pupil.

Question 12

How many rods and cone are on each eye?

Answer 12

120 million rods and 6 million cones

Question 13

Facts about rod cells?

Answer 13

• they only see black and white
• work well in the dark or low levels of illumination
• Perception of fine detail is also not possible at night (Scotopic vision)
• Mainly responsible for perception of movement
• Further away from fovea the more rod cells there are

Question 14

What does visual acuity mean?

Answer 14

Visual acuity means the capacity of the eye to resolve dine details

Question 15

Are there any rods in the fovea?

Answer 15

No

Question 16

Facts about cone cells?

Answer 16

• Cones detect colour and fine detail
• They only work well in bright light
• Many cones are clustered together in fovea

Question 17

For best vision during ‘__’ time is to look directly at the object through the’___’ of eye falling on the’__’

Answer 17

For best vision during day time is to look directly at the object through the leans of eye falling on the fovea

Question 18

Do cones function efficiently during night time?

Answer 18

At night cones in the fovea do not function efficiently, effectively causing a night-blind spot directly in front of you.

Question 19

At night what degree should you focus to view the target best.

Answer 19

At night focus 10-15 degrees to the side of the target for the best results.

If you stare at an object at night, the image begins to fade. Scanning will help to maintain a sharp image.

Question 20

What do the lens do when focusing on near or far objects?

Answer 20

Lens become thicker and rounder focusing on near objects

Lens becomes flatter focusing on object in distance

Question 21

Where is the fovea located?

Answer 21

On the retina

Question 22

How much refraction do the lens do?

Answer 22

30% refraction

Question 23

When is visual acuity best?

Answer 23

When the light falls directly onto the fovea. For best visual acuity we need to be staring directly at the object.

Question 24

What are some visual defects?

Answer 24

Myopia (short sight)
Hypermetropia (long sight)
Presbyopia (age changes)

Question 25

What is myopia?

Answer 25

Someone with myopia, a person can see near objects clearly, but not distant objects. Lens are to weak so the light falls short of retina.

Question 26

What is hypermetropia?

Answer 26

Someone with hypermetropia is a person can see distant objects clearly but not near objects Lens are too powerful so light rays travel to far to focus on the retina.

Question 27

What is presbyopia?

Answer 27

As people age the lens become less elastic and ciliary muscles get weaker In most people over the age of 40, the ability to focus deteriorates

Question 28

Due to the disparity of eyes, each eye views an object from slightly different angle. This is called?

Answer 28

Depth perception.

Question 29

Binocular vision is reliable up to '__' metres after '__' metres we guess

Answer 29

Binocular vision is reliable up to 6 metres after 6 metres we guess

Question 30

Binocular vision up to '__' metres becomes like looking with one eye

Answer 30

Binocular vision up to 60metres becomes like looking with one eye

Question 30

What are two types of binocular cues?

Answer 30

- Accommodative reflex | - Convergence reflex

Question 31

What is accommodative reflex?

Answer 31

Is the contracting and relaxing of the lens using ciliary muscles to adjust to what the eye is trying to focus on whether far or near objects

Question 32

What is convergence reflex?

Answer 32

As an object approaches, the eye must converge to maintain binocular fixation on the target. Through experience, the distance of the object gives a more accurate cue.