Vision

Question 1

Light rays bend to form a sharp image on the retina, this is known as

Answer 1

refraction

Question 2

We can focus on near or distant objects by changing how much we bend the light rays, this is known as

Answer 2

accommodation

Question 3

Sometimes there is a mismatch between how much we bend the light rays which leads to

Answer 3

refractive errors

Question 4

An image is seen through

Answer 4

phototransduction

Question 5

What is accommodation?

Answer 5

The ability to focus on objects which are far away or close by changing how much we bend the light rays

Question 6

What three things comprise accommodation when focusing on something close and happen simultaneously?

Answer 6

Lens changes shape becoming thicker and more spherical
Pupils constrict
Eyes converge

Question 7

Ciliary body contraction causes the ciliary body to

Answer 7

bulge - decreasing the space between the body and the lens

Question 8

What effect does ciliary body contraction have on the suspensory ligaments and therefore the lens?

Answer 8

Suspensory ligaments become relaxed, the lens is no longer under stretch so becomes thicker

Question 9

Is a thicker lens more or less powerful?

Answer 9

More

Question 10

To sharpen the focus on an object, the pupil

Answer 10

constricts - to allow only a few rays from the object to pass through

Question 11

What is the pupillary constrictor?

Answer 11

A concentric muscle around the border of the pupil which gets parasympathetic innervation

Question 12

Eyes converge when

Answer 12

focusing on a close up object

Question 13

What muscles of the eye are used to converge the eyes?

Answer 13

Medial recti muscles of both eyes

Question 14

Why are the medial recti muscles thicker than the lateral recti muscles in humans?

Answer 14

Humans spend a lot of time focussing on close up objects e.g. when reading so the medial recti muscles are used more frequently

Question 15

What is myopia?

Answer 15

Short sightedness

Question 16

What is hyperopia?

Answer 16

Long sightedness

Question 17

What is astigmatism?

Answer 17

Non-spherical curvature of the cornea or lens

Question 18

What is presbyopia?

Answer 18

Long sightedness due to old age

Question 19

What is emmetropia?

Answer 19

perfect vision

Question 20

Myopia causes

Answer 20

close objects to look clear but distant objects to appear hazy

Question 21

What is the most common cause of myopia?

Answer 21

Eyeball too long for the strength of lens and cornea

Question 22

In myopia, when the cornea and lens bend the rays of light, the image is not formed on the retina but

Answer 22

in front of the retina

Question 23

What are the common symptoms of myopia?

Answer 23

Headaches
Complaints from children of being unable to see board in classroom
Divergent squint in infants and pre-verbal children
Toddlers with loss of interest in sports and people

Question 24

How is myopia corrected?

Answer 24

Biconcave lenses or laser eye surgery - decreases bending power

Question 25

Hyperopia causes close objects to appear

Answer 25

hazy, while further away objects are clear

Question 26

What are the symptoms of hyperopia?

Answer 26

Eye strain after reading/working | Convergent squint in children/toddlers

Question 27

How is hyperopia treated?

Answer 27

Biconvex lenses or laser eye surgery

Question 28

What does astigmatism cause?

Answer 28

Close and distant objects to appear hazy, due to the surface of the eye having different curvatures in different medians

Question 29

How is astigmatism corrected?

Answer 29

Using cylindrical glasses which are curved in only one axis, laser eye surgery or toric lenses

Question 30

What happens to the lens in presbyopia?

Answer 30

With increasing age the lens becomes less mobile and less elastic, ciliary muscle still contracts but the lens is more rigid so less able to change its shape

Question 31

How is presbyopia corrected?

Answer 31

Biconvex glasses/lenses for reading

Question 32

What is phototransduction?

Answer 32

The conversion of light energy into an electrochemical response by the photoreceptors (rods and cones)

Question 33

Visible light is an

Answer 33

electromagnetic wave

Question 34

The phototransduced rods and cones activate

Answer 34

the optic nerve neurons which generate an action potential which is transmitted to the brain

Question 35

What is rhodopsin?

Answer 35

A visual pigment found in the rods of the retina - extremely sensitive to light so enables vision in low lighting

Question 36

What will any condition affecting vitamin A absorption affect?

Answer 36

Vision, cause night blindness as well as abnormal conjunctiva and corneal epithelium

Question 37

What two types of light-sensitive cells are contained in the retina?

Answer 37

Rods and cones

Question 38

Rods work in

Answer 38

low light conditions to help with vision at night

Question 39

Cones work in

Answer 39

daylight and are responsible for colour discrimination

Question 40

Colour blindness is usually caused by

Answer 40

faulty cones or a defect in the pathway from the cone to the brain

Question 41

In increased illumination, the parasympathetic system causes the pupils to

Answer 41

constrict

Question 42

In low illumination, the sympathetic system causes the pupils to

Answer 42

dilate

Question 43

What muscles are responsible for the change in pupil diameter?

Answer 43

Constrictor pupillae and dilator pupillae

Question 44

All fibres from the eye pass through the

Answer 44

optic nerve to the optic chiasm

Question 45

The optic chiasm sits on top of the

Answer 45

pituitary gland

Question 46

At the optic chiasm the medial nasal fibres

Answer 46

cross to the opposite side

Question 47

The optic tract contains fibres from

Answer 47

the temporal half of the ipsilateral eye and the nasal fibres from the contralateral eye

Question 48

Fibres from the optic tract synapse at the

Answer 48

Lateral Geniculate Body

Question 49

From the lateral geniculate body, the optic radiation passes

Answer 49

behind the internal capsule to reach the primary visual cortex

Question 50

What lobe is the primary visual cortex found in?

Answer 50

Occipital

Question 51

The right visual cortex sees

Answer 51

the left half of the visual field

Question 52

The intrinsic muscles of the eye control

Answer 52

pupil diameter and help alter the lens curvature in order to see close objects

Question 53

The extrinsic muscles of the eye control

Answer 53

eye movement

Question 54

Name the 6 extra ocular muscles

Answer 54

``` Medial rectus Lateral rectus Inferior rectus Superior rectus Inferior oblique Superior oblique ```

Question 55

The recti muscles of the eye arise from

Answer 55

the apex of the orbit from an annular fibrous ring

Question 56

The superior oblique arises from

Answer 56

the roof of the orbit, posteriorly

Question 57

The inferior oblique arises from the

Answer 57

floor of the orbit, anteriorly

Question 58

What muscle runs superiorly to and elevates the upper eyelid?

Answer 58

Levator palpebrae superioris

Question 59

When the eye is abducted, the superior rectus causes

Answer 59

elevation

Question 60

When the eye is adducted, the superior rectus causes

Answer 60

intorsion

Question 61

When the eye is abducted, the inferior rectus causes

Answer 61

depression

Question 62

When the eye is adducted, the inferior rectus causes

Answer 62

extorsion

Question 63

When the eye is adducted, the superior oblique causes

Answer 63

depression

Question 64

When the eye is adducted, the inferior oblique causes

Answer 64

elevation

Question 65

The medial rectus causes

Answer 65

adduction

Question 66

The lateral rectus causes

Answer 66

abduction