Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BRS YR2 > Visual system > Flashcards

Visual system Flashcards

1
Q

What are the different parts of the extraocular eye?

A

.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the average antero-posterior diameter of the eye in adults?

A

24mm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the sclera?

A
  • tough, opaque tissue that acts as the protective outer coat
  • high water content
  • protects eye and maintains shape
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the cornea?

A
  • transparent, dome shaped window covering the front of the eye
  • low water content
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the role of the cornea?

A
  • refracting surface
  • provides 2/3 of the eye’s focusing power
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the 3 layers of the coat of the eye?

A
  • sclera
  • uvea
  • retina
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the uvea?

A
  • vascular coat of eyeball
  • made up of iris, ciliary body and choroid
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Where is the uvea?

A

between the sclera and retina

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the choroid?

A
  • the middle, pigmented vascular layer of the coat
  • provides circulation to the eye
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the iris?

A
  • coloured part of the eye
  • controls light levels inside the eye
  • sphincter and dilator muscles
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the retina?

A

the innermost neurosensory layer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the role of the retina?

A

responsible for converting light into neurological impulses, transmitted to the brain by the optic nerve

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the role of the crystalline lens?

A

responsible for 1/3 of the refractive power of the eye

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What can happen to lens with age?

A
  • opacification
  • cataract
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the retina? DELETE

A

thin layer of tissue that lines the inner part of the eye

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the role of the retina? DELETE

A

responsible for capturing the light that enters the eye, sent to brain, via the optic nerve

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the role of the optic nerve?

A

transmits electrical impulses from the retina to the brain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Where is the optic nerve?

A
  • connects to the back of the eye near the macula
  • the visible portion of the optic nerve is the optic disc
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Where is the blind spot?

A

on the optic disc

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Why is the optic disc a blind spot?

A

Contains no light sensitive cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the macula?

A

a small and highly sensitive are in the centre of the retina

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the role of the macula?

A

responsible for detailed central vision e.g. reading

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Where is the macula?

A

in the centre of the retina, temporal to the optic nerve

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the fovea?

A
  • the centre of the macula
  • highest concentration of cones
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is central vision?

A
  • detail day vision
  • colour
  • reading
  • facial recognition
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

How does loss of central vision present?

A

Problems with reading and recognising faces

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is used to assess central vision?

A

visual acuity assessment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is the role of peripheral vision?

A
  • shape
  • movement in the environment
  • night vision
  • navigation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

How does loss of peripheral vision present?

A

problems navigating the world

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What is used to assess peripheral vision?

A

visual field assessment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What are the 3 layers of the retina?

A
  1. outer layer of photoreceptors
  2. middle layer of bipolar cells
  3. inner layer of retinal ganglion cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What is the role of the photoreceptors?

A

detection of light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What is the role of the bipolar cells?

A

local signal processing to improve contrast sensitivity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What is the role of the retinal ganglion cells?

A

Transmission of signals from the eyes to the brain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What are the 2 main types of photoreceptors?

A

Rods and cones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What is the structure of rods?

A
  • Longer outer segment with photo-sensitive pigment
  • 100 times more sensitive to light than cones
  • Slow response to light
  • 120 million rods
  • further from fovea
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What are rods responsible from?

A

Responsible for night vision (Scotopic Vision) and peripheral vision

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Describe the structure of cones

A
  • shorter outer segment
  • less sensitive to light
  • faster response
  • 6 million cones
  • closer to fovea
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What are cones responsible for?

A

Daylight fine vision, colour vision (phototopic vision) and central vision

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What are the 2 types of lenses?

A
  • converging (convex)
  • diverging (concave)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

What is a convex lens?

A
  • converging
  • takes light rays and bring them to a point
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

What is a concave lens?

A
  • diverging
  • takes light rays and spreads them outward
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

What is emmiotropia?

A
  • normal vision
  • adequate correlation between axial length and refractive power
  • parallel light rays fall on the retina
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

What is Ametropia?

A
  • mismatch between axial length and refractive power
  • light doesn’t fall on the retina
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

What are the different types of Ametropia?

A
  • near sightedness (myopia)
  • far sightedness (hyperopia)
  • presbyopia
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

What is the mechanism of myopia?

A

parallel rays converge at a focal point anterior to the retina

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

What are the causes of myopia?

A
  • excessive long globe (axial myopia)
  • excessive refractive power (refractive myopia)
48
Q

What are the symptoms of myopia?

A
  • Blurred distance vision
  • Squint in an attempt to improve uncorrected visual acuity when gazing into the distance
  • Headache
49
Q

How do you treat myopia?

A
  • Correction with concave lenses (negative lenses)
  • Correction with contact lenses
  • Correction by removing the lens to reduce refractive power of the eye
50
Q

What is hyperopia?

A

Parallel rays converge at a focal point posterior to the retina

51
Q

What are the causes of hyperopia?

A
  • excessive short globe (axial hyperopia)
  • insufficient refractive power (refractive hyperopia)
52
Q

What are the symptoms of hyperopia?

A
  • visual acuity at near tends to blur relatively early
  • nature of blur is varied
  • blurred vision is more noticeable if person is tired, printing is weak or light inadequate
  • eyepain
  • headache in frontal region
  • burning sensation in the eyes
53
Q

What is the treatment for Hyperopia?

A
  • Correction with concave lens(positive lenses)
  • Correction with positive lens + cataract extraction
  • Correction with contact lens
  • Correction with intraocular lens
54
Q

What is Presbyopia?

A
  • Naturally occurring loss of accommodation (focus for near objects)
  • onset around 40 years old
  • distant vision intact
55
Q

How do you treat Presbyopia?

A
  • reading glasses (convex lenses) to increase refractive power of the eye
  • spectacle lens (Monofocal lenses : spherical lenses, cylindrical lenses, Multifocal lenses)
  • contact lenses
56
Q

What is the purpose of Near Response Triad?

A

adaptation for near vision

57
Q

What is the Near Response Triad?

A
  • Pupillary Miosis
  • Convergence
  • Accomodation
58
Q

What happens in Pupillary Miosis?

A

sphincter pupillae cause the pupil to constrict, increasing the depth of field

59
Q

What happens in Convergence?

A

medial recti contract, adducting the eyes to align both eyes towards a near object

60
Q

What happens in Accomodation?

A

circular ciliary muscles increase refractive power of lens by making it thicker for near vision

61
Q

What is the role of the visual pathway?

A

transmits signal from eye to the visual cortex

62
Q

What are the landmarks of the visual pathway?

A
  • Eye
  • Optic Nerve – Ganglion Nerve Fibres
  • Optic Chiasm – Half of the nerve fibres cross here
  • Optic Tract – Ganglion nerve fibres exit as optic tract
  • Lateral Geniculate Nucleus - Ganglion nerve fibres synapse
  • Optic Radiation – 4th order neuron, sends signals from lateral geniculate ganglion to primary visual cortex
  • Primary Visual Cortex – within the Occipital Lobe
63
Q

What relays information to the visual cortex?

A

Lateral Geniculate Nucleus in Thalamus

64
Q

What is the impact of a lesion anterior to the optic chiasm?

A

affects the visual field in only one eye

65
Q

What is the impact of a lesion posterior to the optic chiasma?

A

affects the visual field in both eyes

  • Right sided lesion: Left Homonymous Hemianopia in Both Eyes
  • Left sided lesion: Right Homonymous Hemianopia in Both Eyes
66
Q

What are the nerves that cross at the optic chiasm responsible for?

A

temporal visual field

67
Q

What are the nerves that do not cross at the optic chiasma responsible for?

A

the nasal visual field

68
Q

What is the impact of a lesion at the optic chiasma?

A

temporal field deficit in both eyes - bitemporal hemianopia

69
Q

What can cause a bitemporal hemianopia?

A

enlargement of a pituitary gland tumour

70
Q

What can cause a homonymous hemianopia?

A

stroke (cerebrovascular accident)

71
Q

What can damage to the primary visual cortex due to stroke cause?

A

Homonymous Hemianopia of the contralateral side, with sparing of macula central vision

72
Q

Why is damage to the primary visual cortex unlikely?

A

receives dual blood supply from both right and left posterior cerebral arteries

73
Q

What happens to the pupil in light?

A
  • constricts
  • circular muscles contract
  • mediated by parasympathetic nerve within CNIII
74
Q

Why does the pupil constrict under light?

A
  • decreases glare
  • increases depth of field
75
Q

What happens to the pupil in dark?

A
  • dilate
  • radial muscles contract
  • mediated by sympathetic nerve within CNIII
76
Q

Why does the pupil dilate in the dark?

A

increases light sensitivity in the dark by allowing more light in

77
Q

What happens in the afferent pathway of the pupillary reflex?

A
  • pupil-specific ganglia exit the posterior third of the optic tract
  • enter the lateral geniculate nucleus
  • synapse at the brainstem pretectal nucleus
  • afferent pathways from each eye synapse at the Edinger-Westphal nucleus on both sides in brainstem
78
Q

What happens in the efferent pathway of the pupillary reflex?

A
  • Edinger-Westphal Nucleus
  • Oculomotor Nerve Efferent
  • Synapses at Ciliary ganglion upon the Short Posterior Ciliary Nerve
  • Pupillary Sphincter
79
Q

What stimulates the efferent pathway on both eyes?

A

the afferent pathway for either eye

80
Q

What is the direct light reflex?

A

constriction of the pupil of the light-stimulated eye

81
Q

What is the consensual light reflex?

A

constriction of the pupil of the other eye (light shone in opposite eye to this one)

82
Q

What happens if the right afferent pupillary pathway is damaged?

A
  • stimulation of the right eye will elicit weak,
    or no pupillary constriction in both eyes.
  • BUT, Normal pupil constriction in both eyes when left eye is stimulated with light
83
Q

What happens if the right efferent pupillary pathway is damaged?

A

no pupillary constriction in the right eye, and normal pupillary constriction in the left eye, whether right eye or left eye is stimulated.

84
Q

How do you detect a relative afferent pupillary defect?

A

swinging torch test

85
Q

What happens in a swinging torch test?

A
  • alternating stimulation of right and left eyes with light
  • both pupils constrict when light swings to undamaged side
  • both pupils paradoxically dilate when light swings to damaged side
86
Q

What are the 6 muscles of the eye?

A
  • medial rectus
  • lateral rectus
  • superior rectus
  • inferior rectus
  • superior oblique
  • inferior oblique
87
Q

What are the 4 straight muscles of the eye?

A
  • medial rectus
  • lateral rectus
  • superior rectus
  • inferior rectus
88
Q

What is the role of the superior rectus?

A

moves the eye up maximally in adducted position

89
Q

What is the role of the inferior rectus?

A

moves the eye down maximally in abducted position

90
Q

Where is the lateral rectus attached?

A

temporal side of the eye

91
Q

What is the role of the lateral rectus?

A

moves the eye towards the outside of the head (towards the temple)

92
Q

Where is the medial rectus attached?

A

on the nasal side of the eye

93
Q

What is the role of the medial rectus?

A

moves the eye toward the middle of the head (towards the nose)

94
Q

Where is the superior oblique attached?

A
  • high on the temporal side of the eye
  • passes under the superior rectus
  • travels through the trochlea
95
Q

What is the role of the superior oblique?

A

moves the eye down and out

96
Q

Where is the inferior oblique attached?

A
  • attached low on the nasal side of the eye
  • passes over the inferior rectus
97
Q

What is the role of the inferior oblique?

A

moves the eye up and out

98
Q

What innervates the lateral rectus?

A

CN 6 - abducens nerve

99
Q

What innervates the superior oblique?

A

CN 4 - trochlear nerve

100
Q

What innervates the superior rectus?

A

CN 3 - superior branch of the oculomotor nerve

101
Q

What is innervated by the superior branch of CN3 (oculomotor nerve)?

A
  • levator palpebrae superioris (raises eyelid)
  • superior rectus
102
Q

What is innervated by the inferior branch of C3 (oculomotor nerve)

A
  • inferior rectus
  • medial rectus
  • inferior oblique
103
Q

What innervates the inferior rectus?

A

CN 3 - inferior branch of the oculomotor nerve

104
Q

What innervates the medial rectus?

A

CN 3 - inferior branch of the oculomotor nerve

105
Q

What innervates the inferior oblique?

A

CN 3 - inferior branch of the oculomotor nerve

106
Q

What innervates pupil constriction?

A

CN 3 - the parasympathetic branch of the inferior oculomotor nerve

107
Q

What is abduction?

A

moving away from the nose.

108
Q

What is adduction?

A

moving towards the nose.

109
Q

How does third nerve palsy present?

A
  • Affected eye down and out due to unopposed SO and LR
  • Droopy eyelid (loss of elevator palpebrae superioris)
  • pupil dilated due to loss of parasympathetic action
110
Q

What can cause third nerve palsy?

A

aneurysm

111
Q

What muscles are affected in third nerve palsy?

A

everything but:

  • lateral rectus (abduction)
  • superior oblique (depression)
112
Q

How does sixth nerve palsy present?

A
  • Affected eye unable to abduct and deviates inwards due to unopposed MR
  • Double vision worsen on gazing to the side of the affected eye
113
Q

What can cause sixth nerve pasly?

A

cranial pressure

114
Q

How does fourth nerve palsy present?

A
  • affected eye moves up and in
  • struggle with actions which invlolve looking down (e.g. reading)
115
Q

What can cause fourth nerve palsy?

A
  • congenital
  • trauma

BRS YR2 (67 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions