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Neurology System > Vision > Flashcards

Vision Flashcards

1
Q

What is refraction?

A

Bending of light when it passes from one optical medium to another
The bending of light rays to form a sharp image on the retina

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2
Q

What is accommodation?

A

The focusing of a far off or near object by how much we bend the light rays

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3
Q

What is a refractive erros?

A

When there is a mismatch of bending the light rays

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4
Q

Which components of the eye are transparent?

A

Cornea
AH
Lens
VH

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5
Q

What are the two main benders of light in the eye?

A

Cornea

Lens

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6
Q

What is the most powerful bender of light?

A

Cornea

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7
Q

What are the 3 things that cause accommodation?

A

Pupil constricts
Eyes converge
Lens changes shape

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8
Q

What is the sequence of events that occur to thicken the lens?

A

o Want to thicken the lens – ciliary muscle
o Ciliary muscle contracts making the ciliary body bulge
o Space in the middle decreases and the suspensory ligaments become lax
o This means the lens is no longer being pulled
o Basically just flops down and becomes more spherical (thicker)
o This bends the divergent rays

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9
Q

Do eyes converge or diverge when an object is up close?

A

Convege

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10
Q

Which muscles causes convergence?

A

Medial Rectus

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11
Q

Which CN controls the medial rectus?

A

CN III

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12
Q

Which muscle is thicker medial or lateral rectus?

A

Medial

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13
Q

Which of the 3 aspects of accommodation is examinable?

A

Pupillary constriction

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14
Q

Which part of the NS controls the constriction of pupils?

A

Parasympathetic innervation

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15
Q

What is myopia?

A

Short sightedness

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16
Q

What is hyperopia

A

Long sightedness

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17
Q

What is a astigmatism?

A

Non-spherical curvatures of the cornea

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18
Q

What is prebyopia?

A

Long sightedness of old age

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19
Q

What is short sightedness?

A

When close objects appear clear and distant ones hazy

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20
Q

What is the most common cause of myopia?

A

Eyeball is too long

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21
Q

Where does the image form in myopia?

A

In front of the lens

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22
Q

What are the symptoms of myopia?

A

Headaches

Complain of not being able to see board or distant objects

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23
Q

What are infant symptoms of myopia?

A

Loss of interest in sports/people

More interested in books/pictures

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24
Q

What is the treatment for myopia?

A

Bi concave lenses
Spectacles
Contact lenses
Laser eye surgery

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25
Q

What is long sightedness?

A

When distant objects appear clear

Close objects appear hazy

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26
Q

What is the main cause of hyperopia?

A

Eyeball is too short

Or lens is too flat

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27
Q

Where is the image formed in hyperopia?

A

Behind the retina

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28
Q

Why can accommodation not just be used to correct hyperopia?

A

Use more and more power for seeing close up until all accommodative power has gone

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29
Q

What are the symptoms of hyperopia?

A

Glasses
Contact lenses
Laser eye surgery

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30
Q

What can be seen in children with hyperopia?

A

Convergent squint

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31
Q

Why is immediate correction of convergent squint in children necessary?

A

To preserve vision

and prevent a lazy eye

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32
Q

What is astigmatism?

A

When close and distant objects appear hazy

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33
Q

What contact lenses are needed in astigmatism?

A

Toric lenses

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34
Q

Which glasses are neededin astigmatism?

A

Cylindricallens

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35
Q

What is the cause of presbyopia?

A

With age the lends becomes less elastic

Accommodation power weakens

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36
Q

When does presbyopia usually start?

A

In the 5th decade of life

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37
Q

What is phototransduction?

A

The conversion of light energy to an electrochemical response by the photoreceptors

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38
Q

What are the 2 types of photoreceptors?

A

Rods and cones

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39
Q

What do the phototransduced rods and cones need to activate?

A

Optic nerve neurons

To generate and AP

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40
Q

What is the visual pigment in rods?

A

Rhodopsin

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41
Q

What is the visual pigment in cones?

A

Opsin

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42
Q

What are the 3 types of cones?

A

S, M and L

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43
Q

What do the 3 different types of cones all respond to?

A

Different wavelengths of light

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44
Q

What does rhodopsin consist of/

A

Opsin + 11-cis Retinal

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45
Q

Where is vitamin A supplied?

A

Through the diet

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46
Q

What is rhodopsin?

A

Integral transmembrane helical protein

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47
Q

What is retinal?

A

Chromophore

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48
Q

What is retinal derived from?

A

Vitamin A

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49
Q

What is opsin?

A

A G-coupled protein

50
Q

What are the 2 conformations of retinal?

A

Cis and trans

51
Q

What happens when light hits retinal?

A

Changes from cis to trans conformation

52
Q

Why does rhodopsin split?

A

Because not all trans-retinal can fit into the opsin

53
Q

How is visual pigment regenerated?

A

Dietary vitamin A goes back to form 11 cis -retinal
This then joints the opsin
Forms rhodopsin

54
Q

Why is a constant supply of vitamin A require?

A

because not all vitamin A is regenerate to form retinal

some of it does not combine with opsin and gets used instead to form an ester

55
Q

In what conditions can vitamin A deficiency occur?

A

Coeliac

Sprue

56
Q

What is your visual field?

A

Everything you see with one eye including the periphery

57
Q

How are images of objects in your filed of vision formed?

A

Upside down

58
Q

Where are upside images inverted?

A

on the retain

59
Q

Where is the left half of the visual field seen?

A

On the right side of the retina

60
Q

Where is the right visual field seen?

A

On the left side of the retina

61
Q

Where do fibres from the optic nerve pass?

A

The optic chiasma

62
Q

At the optic chiasma which fibres cross?

A

Medial ones

63
Q

Which fibres cross over at the chiasma nasal or temporal?

A

Nasal

64
Q

Where do fibres from the optic tracts synapse?

A

At the LGB of the thalamus

65
Q

Where do optic fibres pass from the LGB?

A

Behind the internal capsule to reach the primary visual cortex

66
Q

What is area 17?

A

Primary visual cortex

67
Q

Where is area 17 located?

A

Occipital lobe

68
Q

Which cortex sees the left half of the visual field?

A

Right cortex

69
Q

Which cortex sees the right half of the visual field?

A

Left cortex

70
Q

When the right optic nerve is damaged what do you expect to see?

A

Blindness in the right eye

Entire eye has been affected

71
Q

When the optic chiasma is interrupted in the middle what do you expect to see?

A

Bitemporal hemianopia

Naso fibres are affects meaning lateral vision is lost

72
Q

When the right optic tract is damage what do you expect?

A

Left side blindness

Contralateral homonymous hemianopia

73
Q

What is the function of intrinsic muscles of the eye?

A

Control pupil diameter an alter lens curvature (accommodation)

74
Q

What is the function of extrinsic eye muscles?

A

To move the eyeball

75
Q

What are the muscles of the eye?

A 
MR 
LR 
SR 
IR 
IO 
SO
76
Q

Where do the recti muscles arise from??

A

Apex of the orbit from an annular fibrous ring

77
Q

Where does the SO muscle arise?

A

The roof of the orbit posteriorly

78
Q

Where does the IO arise from?

A

The roof of the orbit anteriorly

79
Q

Which is the only eye muscle to originate anteriorly?

A

IO

80
Q

Which muscle lies just above the SR?

A

LPS

Levator palpebrae superioris

81
Q

Which muscles closes the eyelid?

A

LPS

82
Q

Where do the recti muscles insert?

A

Onto the sclera anteriorly

83
Q

Where do the oblique muscles insert?

A

On to the sclera posteriorly

84
Q

Which CN supplies the extrinsic muscles of the eye?

A

SO CN IV
LR CN VI
and everything else by CN III

85
Q

What term is used to describe eye movements of both eyes?

A

Binocular

86
Q

What is meant by uniocular?

A

Movement of 1 eye

87
Q

When LR has abducts the eye what does SR and IR cause?

A

SR - elevation

IR - depression

88
Q

When MR has adducted the eye what does SR and IR cause?

A

SR - intorsion

IR - extorsion

89
Q

When the eye ball is adducted what does SO and IO cause?

A

SO - depression

IO - elevation

90
Q

When the eyeball is abducted what does SO and IO cause?

A

SO - intorsion

IO - extorsion

91
Q

What is the primary action of the extrinsic eye muscles?

A 
MR - adduction 
LR - abduction 
SR - elevation 
IR - depression 
SO - intorsion 
IO - extorsion
92
Q

What is the secondary action of SR, IR

SO, IO?

A

SR - adduction
IR - abduction
SO - depression
IO - elevation

93
Q

What is the tertiary action of SR, IR, SO ,I O?

A

SR - intorsion
IR - Extorsion
SO - Abduction
IO - adduction

94
Q

What is esotropia?

A

Convergent squint

95
Q

What is exotropia?

A

Divergent squint

96
Q

What is amblyopia?

A

Lazy eye

Where brain supresses the image of one eye leading to poor vision in that eye

97
Q

How is amblyopia treated?

A

With an eye patch to try and stimulate the lazy eye

98
Q

What is diplopia?

A

Double vision

99
Q

What are the intrinsic muscles of the eye?

A

Ciliaris muscle
Constrictor pupillae
Dilator pupillae

100
Q

What is the ection of the cilaris muscle?

A

Muscles that contracts to make the lens thicker

101
Q

Where is the constrictor pupillae found?

A

In the iris at the pupillary border

102
Q

What is the action of the constrictor pupillae?

A

Constrict the pupil

103
Q

Which part of the NS innervated the constrictor pupillae?

A

Parasympathetic

104
Q

Where is the dilator pupillae found?

A

Radially running muscle in the iris

105
Q

What is the action of dilator pupillae?

A

Works to dilate the pupils

106
Q

What is the pupillary reaction to increased illumination?

A
  • parasympathetic system innervated

- both pupils constrict

107
Q

What is the pupillary reaction to decreased illumination?

A

Sympathetic system innervated

Both pupils dilate

108
Q

How do you elicit the pupillary reflex?

A

Start in dimly lit room
Put pen torch in front of the eye
Both pupils should be dilated

109
Q

Where is CN III nuclei located?

A

In the midbrain

110
Q

Where do fibres destined to activate the pupillary reflex go?

A

Leave the optic tract and go to the midbrain where CN III nuclei is located

111
Q

DO fibres destined to activate the pupillary reflex go to the LGB?

A

No

112
Q

What are common causes of absent/abnormal pupillary reflex?

A

Any abnormality of the afferent, centre of efferent part of the reflex
Diseases of the retina
Diseases of the optic nerve
Diseases of CN III

113
Q

Where is optic neuritis commonly seen?

A

MS

114
Q

Which is the afferent limb of the pupillary reflex?

A

CN II

115
Q

Which is the efferent limb of the pupillary reflex?

A

CN III

116
Q

What is anisocria?

A

Pupils of different side

117
Q

What is ptosis?

A

Drooping of the eyelid

118
Q

Which segment of the NS has thoracolumbar outflow?

A

Sympathetic

119
Q

What is horners syndrome?

A

Horner syndrome is a combination of signs and symptoms caused by the disruption of a nerve pathway from the brain to the face and eye on one side of the body.

120
Q

What are the common symptoms of horners syndrome?

A

Typically, Horner syndrome results in a decreased pupil size, a drooping eyelid and decreased sweating on the affected side of your face.

Neurology System (35 decks)

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