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Year 2 BRS Neuro > Visual System > Flashcards

Visual System Flashcards

1
Q

Duction

A

Duction – Eye Movement in One Eye

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2
Q

‘Simultaneous movement of both eyes in the same direction’

what is this called?

A

Version

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3
Q

_______ : Simultaneous movement of both eyes in the opposite direction

A

Vergence

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4
Q

Convergence

A

– Simultaneous adduction (inward) movement in both eyes when viewing a near object

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5
Q

Saccade

A 
– short fast burst, up to 900°/sec
Reflexive saccade to external stimuli
Scanning saccade
Predictive saccade to track objects
Memory-guided saccade
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6
Q

Lacrimal system

types of tears

A

Basal
Reflex
emotional

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7
Q

Tears - where produced
where do they flow from?
gather?
exit?

A

Drain through two puncta openings on medial lid margin

flow through superior and inferior canaliculi
gather in tear sac
exit via tear duct into nasla cavity

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8
Q

What is a basal tear?

A

It produces tear at a constant level,

even in the absence of irritation or stimulation

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9
Q

Reflex tears

A

response to occular irritation , increased tear production

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10
Q

Emotional tear

A

crying

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11
Q

Tear reflex pathway

A

afferent pathway > CNS > Efferent pathway > lacrimal gland
afferent pathway : cornea, CNV1 [ophthalmic trigeminal ]
efferent pathway : parasympathetic innervates lacrimal gland
Neurotransmitter : acetylcholine

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12
Q

What is the ‘Tear Film’ -
Where is it found?
Use?

A

Thin layer of fluid : composed of 3 layers> lipid layer, aqueous> mucious layer

covers healthy cornea, maintaining smooth cornea to air surface

important for maintaining clear vision, removal of debris

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13
Q

Why is the layering of the tear film important?

A

lipid layer allows for reduced tear film evaporation
produced by meibomian glands

aqueous layer important in protection against harmful bacteria ; provides nutrients and oxygen to surrounding tissue

mucinous layer contains mucin

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14
Q

Thin, transparent tissue that covers the outer surface of the eye

A

Conjunctiva

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15
Q

3 layers forming coat of eye?

A

Sclera
Choroid: pigmented vascular
retina : ligh into neuro impulses transmitted to brain via optic nerve

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16
Q

sclera properties

A

high water content

the tough, opaque tissue that serves as the eye’s protective outer coat.

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17
Q

what happens if you hydrate the eye?

A

It becomes white
usually low water content
so can be a clear window to look through / look into eye

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18
Q

how does cornea get oxygen / glucose?

A

oxygen from air

glucose via fluid absorbed by endothelium

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19
Q

uvea

A

lies between sclera and retina

Iris, Ciliary Body, Choroid

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20
Q

How are cataracts formed?

A

Lens losing its transparency with ages resulting in an opaque lens known as Catarct

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21
Q

Most sensitive part of the retina?

A

fovea found within the macula

It has the highest concentration of cones, but a low concentration of rods

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22
Q

Retinal Structure

A

Photoreceptors [1st] > Bipolar Cells [2nd] > Retinal ganglion cells [3rd]

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23
Q

Rods vs Cones

A

Rods : Night vision , 100 times more sensitive to light : 120 mill
Cones: faster response , less sensitivity. fine vision, colour vision 6 million

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24
Q

Deuteranomaly

A

not completely colour blind but they don’t perceive the colour red.

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25
Q

full colour blindness

A

achromatopsia

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26
Q

what is responsible for capturing light rays?

A

retina

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27
Q

where is the macula located?

A

centrally in the retina,

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28
Q

where is the fovea found?

A

centre of macula

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29
Q

peripheral vision?

A

extensive loss of visual field
navigation vision loss
shape, movement night vision

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30
Q

central vision

A

detail day vision, colour

fovea has the highest concentration of cone photoreceptors

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31
Q

refraction

A

light goes from one medium to another velocity changes

light bends path changes

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32
Q

convex

A

takes light rays and brinsg them to a point

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33
Q

concave lens

A

diverging lens which takes light rays and spreads them outwards

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34
Q

example of a converging lens?

A

camera

convex lens

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35
Q

adequate correction between axial length and refractive power is known as what?

A

emmetropia

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36
Q

ametropia is ?

A

refractive error

axial length and refractive power mismatch

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37
Q

myopia

A 
short sight 
blurred distance vision 
squinting
headache
treatment 
correction with a negative lens
contact lens
removal of lens to reduce refractive power of the eye by surgery
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38
Q

hyperopia

A

Long sighted

light rays converge BEHIND retina = blurred NEAR vision so reading
eye strain / hence headache

why?
short globe
not enough refractive power

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39
Q

hyperopia symptom

A

visual acuity at near tends to blur relatively early
short sight
children can get learning difficulty

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40
Q

treatment

A

glasses
lens
surgery

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41
Q

astigmatism

A

2 focal lines rather 1 focal point - 2 points

heredity

refractive media is not spherical

refract differently as refractive media is not spherical

= blurred vision, frontal headache
eye strain and pain

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42
Q

astigmatism

symptoms

A

asthenopic symptoms
blurred vision
distortion of vision
head tilting / turning

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43
Q

adaptation for near vision

A

pupillary miosis to increase depth of field
convergence to align both eyes towards a near object
accommodation to increase the refractive power of the lens for near vision

44
Q

presbyopia

A

onset 40 onwards
naturally occuring loss of accommodation
corrected by reading glasses

45
Q

treatment for presbyopia

A

bifocal glasses
trifocal glasses
progressive power glasses

46
Q

presbyopia correction

A

spectacle lenses : monofocal lenses , cylindrical lenses, multifocal lenses

47
Q

signal from Eye to Visual Cortex pathway

A 
eye 
optic nerve 
optic chiasm 
optic tract
lateral geniculate nucleus 
optic radiation - 4th order neuron 
primary visual cortex or striate cortex
48
Q

visual pathway retina

first order neurones are ?

A

rod and cone retinal photoreceptors

49
Q

second order neurons?

A

retinal bipolar cells

50
Q

third order neurons

A

retinal ganglion cells

51
Q

what are third order neurons?

A

optic nerve CN II
partial decussation at optic chiasm - 53%
optic tract
LGN relays visual info to visual cortex

52
Q

where is the lateral geniculate nucleus

A

thalamus

53
Q

if lesion is found anterior to optic chiasm?

A

then visual defect is in one eye primarily

i

54
Q

crossed fibres originate

A

temporal visual field

55
Q

uncrossed fibres

A

nasal visual field

56
Q

what produces contralateral homonymous Hemianopia?

A

As a rule, visual pathway lesion posterior to the chiasma produces contralateral Homonymous Hemianopia in both eyes.

57
Q

Bitemporal Hemianopia

causes?

A

Damage to the crossed nasal ganglion fibres,
results in deficit in temporal visual field loss in both eyes simultaneously

pituitary adenoma

58
Q

causes of

Homonymous Hemianopia

A

stroke

Cerebrovascular accident

59
Q

Homonymous Hemianopia

with Macular sparing

A

stroke causes primary visual cortex damage
leads to contralateral homonymous hemianopia

but macula is spared - as the area representing it receives dual blood supply from BOTH right and left posterior cerebral arteries

60
Q

shine light
pupillary response?

which nerve?

A

pupil constriction
decrease spherical abberations&glare

mediated by CN III - PARAsympathetic nerve

61
Q

dark

pupillary response?

A

dilatation increases

mediated by sympathetic nerve : iris radial muscle

62
Q

afferent pathway

draw this out

A

rod & cone photoreceptors synapse on Bipolar cells > synapse on retinal ganglion cells
pupil- specific ganglion cells exits at posterior third of optic tract before entering lateral geniculate nucleus
afferent pathway synapses on Edinger-westphal nuclei

63
Q

where is the edinger-westphal nucleus?

A

brainstem

64
Q

efferent pathway

A

edinger-westhpal nucelus > occulomotor nerve efferent >
synapses at ciliary ganglion
short posterior ciliary nerve
pupillary sphincter

65
Q

what is the efferent pathway mediated by?

A

parasympathetic nerve

66
Q

afferent pathway in left eye senses bright light

what happens?

A

pupillary constriction in both eyes

as afferent pathway stimulates efferent pathway of both eyes

67
Q

Pupillary Reflex afferent pathway

A

A small sub-section of retinal ganglion cells participate in the Pupillary Reflex Pathway.

They exit the Optic Tract before the Lateral Geniculate Ganglion,
and synapse upon the Dorsal Brain Stem,
as shown by the red and green pathways in the diagram

68
Q

consensual light reflex?

why does this happen?

A

Consensual Light Reflex refers to the constriction of the pupil from the fellow eye.

neurological basis : afferent pathway stimulates both efferent pathway

69
Q

efferent defect in left eye

response to light shone in left eye?

A

right eye constricts
left eye unresponsive
right eye constricts regardless of light shone in R/L eye

70
Q

afferent right eye defect ?

pupillary response to light?

A

weak pupillary reflect in both eyes

71
Q

how to demonstrate weakened response ?

A

stimulate one eye at a time
swinging torch test
when light is in undamaged eye both pupils are constricted
when light is swung to damaged eye, pupils actually dilate as there is relative to the other eye reduced drive for pupillary constriction
- damaged afferent pathway unable to process to brainstem that bright light is being shone as it is weak compared to to other eye

72
Q

convergence happens when?

A

viewing a near object

simultaneous adduction, inward movement of both eyes

73
Q

vergence happens when?

A

simultaneous movement of both eyes in the opposite direction

74
Q

6 muscles of the eye?

A 
4 straight muscles 
superior rectus 
medial rectus 
lateral rectus 
inferior rectus

superior oblique
inferior oblique

75
Q

superior oblique

A 
- attached high on temporal side 
passes under the superior rectus 
moves eye 
DOWN & OUT
travels through tochlea
76
Q

which muscle moves the eye DOWN and OUT?

A

superior oblique

77
Q

which 3 cranial nerves are involved in eye movements?

A

CN III
CN IV
CN VI

78
Q

what is eye movement in one eye called?

A

Duction

79
Q

what is version?

A

simultaneous movement of BOTH eyes in Same direction

80
Q

simultaneous movement of BOTH eyes in OPPOSITE direction

A

vergence

81
Q

which muscle moves eye up?

A

superior rectus

attached at 12 o’clock

82
Q

inferior rectus

eye movement?

A

moves eye down

83
Q

where does the lateral rectus attach?

where does it move eye?

A

temporal side of the eye
at 3 o’clock
moves eye toward outside of head

84
Q

eye movement

Up and OUT

A

inferior oblique
attached low on the nasal side of the eye
diagonal pattern of movement

85
Q

when does Saccade occur?

A

scanning text when reading a book

86
Q

which muscle doesnt come from a cone at the back of the orbit?

where does it come from

A

inferior oblique

comes in nasally

87
Q

medal rectus

A

attaches nasal side

moves eye toward the middle

88
Q

which muscle raises the eyelid?

what is it’s innervation

A

levator palpebrae superioris

3rd CN

89
Q

which muscles are innervated by CN III

A

superior branch-

1) superior rectus,
2) levator palpebrae superioris

inferior branch

1) Inferior Rectus – depresses eye
2) Medial Rectus – adducts eye
3) Inferior Oblique – elevates eye
4) Parasympathetic Nerve – constricts pupil

90
Q

depression of eye ?

A

CN 3
inferior branch
inferior rectus muscle

91
Q

superior oblique

innervation

A

CN IV
tochlear
depresses eye

92
Q

Abducens

6th CN

A

lateral rectus
lateral
abducts eye

93
Q

what causes adduction?

A

medial rectus innervated by inferior branch of CN III

Oculomotor nerve

94
Q

when does the oculomotor divide?

A

when it enters the orbit

divides into superior and inferior

95
Q

lateral rectus muscle testing ?

A

lateral Rectus muscle action is best tested in the abducted position

96
Q

medial rectus muscle action

A

Medial Rectus muscle action is best tested in the adducted position.

97
Q

Superior Rectus muscle action

A

Superior Rectus muscle action is best tested in the elevated and abducted position.

98
Q

Inferior Rectus muscle action

A

Inferior Rectus muscle action is best tested in the depressed and abducted position.

99
Q

.

Inferior Oblique is best tested

A

Inferior Oblique is best tested in the elevated and adducted position

100
Q

Superior Oblique is best tested

A

Superior Oblique is best tested in the depressed and adducted position.

101
Q

Supraduction

A

Supraduction – one eye

102
Q

Supraversion

A

Supraversion – both eyes

103
Q

Dextroversion

A

eye movement to right

104
Q

Levoversion

A

left eye movement

105
Q

3rd nerve palsy

A 
down and out eye 
droopy eyelid( levator palpebrae superioris)
106
Q

why does the eye droop down and out in 3rd nerve palsy

A

Unopposed superior oblique innervated by fourth nerve (down)

Unopposed lateral rectus action innervated by sixth nerve (out)

107
Q

6th nerve palsy

A

inability to abduct
deviated inwards
double vision worsen on gazing to the side of the affected eye

Year 2 BRS Neuro (8 decks)

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