Brainscape's Knowledge GenomeTM

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


See full index

BRS Year 2 > Visual System > Flashcards

Visual System Flashcards

1
Q

when are tears produced by the lacrimal gland?

A

basal, reflex and emotional responses

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

what is the control of a tear reflex ie a bug lands on eye

A

afferent - CN V1 opthalmic trigeminal
efferent - parasympathetic
acetylcholine neurotransmitter

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

what is the route of a tear from lacrimal gland to nasal cavity?

A

lacrimal gland - drain through two puncta
flow through superior and inferior canaliculi
gather in tear sac
exit through tear duct into nasal cavity

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

what is the tear film?

A

most superficial layer of eye - maintains a smooth cornea-air surface
supplies oxygen to cornea

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

what is the role of the tear film?

A

supplies oxygen to cornea
bactericidal
removes debris and dust

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what are the 3 layers of the tear film?

A

lipid outer layer, aqueous layer, mucinous layer on cornea surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is the conjunctiva?

A

thin, transparent tissue covering outer surface of the eye

lines eyelids and visible part of the eye

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what are the 3 tissue layers of the eyeball?

A

sclera
choroid
retina

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

what is the sclera?

A

the white of the eye
tough, opaque outer coat
high water content

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is the cornea?

A

transparent, dome shaped window covering front of eye
low water content
provides 2/3 of focusing power

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what are the layers of the cornea?

A 
epithelium
bowmans membrane
stroma
descemets membrane
endothelium - pumps fluid out of cornea to prevent oedema
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is the uvea?

A

choroid, iris and ciliary body

most vascular part of the eye

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

what is the choroid?

A

lies between retina and sclera

layers of blood vessels

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

what is the iris?

A

muscular to dilate and constrict the pupil size

controls light levels inside the eye

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

what is the structure of the lens?

A

outer acellular capsule

regular inner elongated cell fibres

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

what is the function of the lens?

A

transparency
refractive power and 1/3 of focusing power
accomodation
elasticity

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

what is the retina?

A

thin layer of tissue lining the inner eye

captures light rays and send to optic nerve

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

what is the optic disk?

A

visible portion of the optic nerve

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what is the blind spot and why does it occur?

A

where the optic nerve meets the retina

there are no light sensitive cells

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

where does the optic nerve join the eye?

A

back of the eye, near the macula

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

what is the macula?

A

the centre of the retina highly sensitive for detailed central vision

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

what is the centre of the macula called?

A

fovea

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

what is the role of the fovea?

A

appreciates detail and focuses central vision

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

what is central vision?

A

detail day/colour vision
reading, facial recognition
by fovea of macula

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

what is the fovea?

A

most sensitive part of retina - centre of macula

highest concentration of cones, low concentration of rods

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

what is peripheral vision?

A

shape, movement, navigation and night vision

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

how is central vision tested?

A

visual acuity assessment

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

how is peripheral vision tested?

A

visual field assessment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

what happens with loss of central vision?

A

poor visual acuity e.g reading

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

what happens with loss of peripheral vision?

A

inability to navigate environment, patient may need white stick even with perfect visual acuity

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

what is the overall structure of the retina?

A

outer - photoreceptors (1st order neuron)
middle - bipolar cells (2nd order)
inner - retinal ganglion cells (3rd order)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

what is the function of retinal 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 function of bipolar cells of the retina?

A

local signalling processing to improve contrast sensitivity and regulate sensitivity

transmits from photoreceptors to retinal ganglion cells

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

what is the function of retinal ganglion cells of the retina?

A

transmission of signal from eye to brain

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

what are the classes of photoreceptors?

A

rods

cones

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

what are rods?

A

long outer segment
contains photo-sensitive pigment
slow response to light and responsible for NIGHT vision

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

which is more abundant, rods or cones?

A

rods 120mil to 6 mil cones

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

what are cones?

A

shorter outer segment
less sensitive to light as rods but faster response
day, fine vision and colour

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

which cones detect blue wavelengths?

A

s cones

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

which cones detect green light?

A

m cones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

which cones detect red light?

A

L cones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

what is deuteranomoly?

A

not being able to perceive the colour red

most common colourblindness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

what is achromatopsia?

A

full colour blindness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

what is the ishihara test used for?

A

to detect colourblindness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

what is the index of refraction (n) and how is it calculated?

A

ratio of the speed of light before and after hitting a boundary
speed of light in vaccum (air)/speed of light in new medium

46
Q

what happens when light meets a boundary?

A

some is reflected, some refracts through the boundary into the new medium

47
Q

what are the two types of lenses and how do they differ?

A

convex - takes light rays at brings them to a point

concave - takes light rays and spreads them outwards

48
Q

what is emmetropia?

A

basically normal, clear vision
adequate correlation between axial length and refractive power
parallel light rays fall on the retina - no accomodation

49
Q

what is ammetropia?

A

mismatch between axial length and refractive power

parallel rays dont fall on retina

50
Q

what are the types of ametropia?

A

myopia
hyperopia
astigmatism
presbyopia

51
Q

what is myopia?

A

near-sightedness (far objects are blurry, close objects in focus)
focal point of light rays falls short of the retina

52
Q

what are the causes of myopia?

A

excessive long globe (axial myopia) more common

excessive refractive power (refractive myopia)

53
Q

what are the symptoms of myopia?

A

blurred distance vision
squint in an attempt to improve uncorrected visual acuity
headaches

54
Q

how is myopia treated?

A

negative/diverging (concave) lenses
contact lenses
removal of lens

55
Q

what is hyperopia?

A 
far sightedness (close objects blurry, distance fine)
focal point of light rays falls behind retina
56
Q

what are the causes of hyperopia?

A

excessive short globe (axial hyperopia)

insufficient refractive power (refractive hyperopia)

57
Q

what are the symptoms of hyperopia?

A

ranges from inability to read fine print to clear near vision but is suddenly and intermittently blurry
bad reading vision
eyepain, headache, burning eyes, blepharoconjunctivitis
amblyopia if uncorrected

58
Q

how is hyperopia treated?

A

positive/converging lens (convex)
contact lenses
positive lens + cataract extraction
intraocular lens surgery

59
Q

what is astigmatism?

A

parallel rays come to focus in two focal lines

hereditary condition

60
Q

what are the causes of astigmatism?

A

non-spherical refraction media (cornea)

61
Q

what are the symptoms of astigmatism?

A

headache, eye pain
blurred vision
distortion of vision
head tilting and turning

62
Q

how is astigmatism treated?

A

cylindrical lenses, surgery

irregular astigmatism treated by rigid cylindrical lenses, surgery

63
Q

what is the near response triad?

A

an adaption for near vision
pupils constrict - pupillary miosis (sphincter pupillae) to increase depth of field
convergence (medial recti from both eyes) to align eyes towards near object
accomodation (circular ciliary muscle) to increase lens’ refractive power

64
Q

what is presbyopia?

A

naturally occuring loss of accomodation/focus of near objects
distant vision intact, onset from 40+

65
Q

how is presbyopia treated?

A 
reading glasses (convex)
bifocal glasses
trifocal glasses
progressive power glasses
contact lenses
spectacle lenses - monofocal. spherical, cylindrical, multifocal
66
Q

what are the drawbacks of contact lenses?

A

careful daily cleaning and disinfection needed
expense
risk of complications

67
Q

what are the complications of contact lenses?

A

infectious keratitis
giant papillary conjunctivitis
corneal vascularisation
severe chronic conjunctivitis

68
Q

what are intraocular lenses?

A

replacement of cataract crystalline lens
best optical correction for aphakia (no lens)
avoids significant magnification/distortion by spectacle lenses

69
Q

what is the process of LASIK surgery?

A 
initial cutting of corneal flap
flipping of corneal flap
photorefractive treatment (laser)
corneal stroma reshaped post laser
corneal flap put back in place
70
Q

give an example of an intraocular lens and its use

A

Staar intra-collamer lens (ICL)

correction of myopia and astigmatism

71
Q

describe how clear lens extraction happens

A

natural lens is removed using a phaco tip

artificial intraocular lens inserted

72
Q

what retinal cells make up the optic nerve?

A

retinal ganglion cells

73
Q

what is the role of the lateral geniculate nucleus?

A

ganglion nerve fibres synapse here to form the optic radiation (4th order neurons)

74
Q

where do the retinal ganglion cell fibres decussate?

A

53% decussate in the optic chiasm (nasal retina)

75
Q

how do lesions anterior to the optic chiasm present?

A

affect visual field in one eye only

76
Q

how do lesions posterior to the optic chiasm present?

A

affect visual field in both eyes

77
Q

which fibres decussate at the optic chiasm?

A

nasal retina aka temporal visual field (due to image flipping)

78
Q

which fibres don’t cross at the optic chiasm?

A

temporal retina aka nasal visual field (due to image flipping)

79
Q

how does a lesion at the optic chiasm present?

A

temporal field deficit in both eyes - bitemporal hemianopia

damages crossed ganglion fibres from nasal retina in both eyes

80
Q

how does a right sided lesion posterior to the optic chiasm present?

A

left homonymous hemianopia in both eyes

81
Q

how does a left sided lesion posterior to the optic chiasm present?

A

right homonymous hemianopia in both eyes

82
Q

what are the causes of bitemporal hemianopias?

A

enlargement of pituitary gland tumour

83
Q

what are the causes of homonymous hemianopia?

A

stroke

84
Q

what is the cause of homonymous hemianopia with macular sparing?

A

damage to primary visual cortex ie stroke (appears contralaterally to hemisphere damaged)

85
Q

what blood vessel supplies the part of the visual cortex which is responsible for representing the macula?

A

posterior cerebral arteries (dual blood supply from both sides arteries)
therefore macula is likely to be spared in strokes

86
Q

how does pupillary constriction occur?

A

parasympathetic stimulation causes circular muscles to contract, radial muscles relax

87
Q

describe the direct light pupillary reflex

A

optic nerve receives light signals from retina
synapses in pretectal nucleus and then Edinger-Westphal in midbrain
oculomotor nerve carries impulse through motor branches to the ciliary ganglion, short ciliary nerves constrict the sphincter pupillae

88
Q

what is the direct pupillary reflex?

A

constriction of pupil in light stimulated eye

89
Q

how does the consensual light reflex occur?

A

the optic nerve activates the efferent pathway in both eyes therefore
optic nerve receives light signals in one eye
synapses in pretectal nucleus and then Edinger-Westphal in midbrain for both eyes
oculomotor nerve carries impulse through motor branches to the ciliary ganglion, short ciliary nerves constrict the sphincter pupillae of both eyes

90
Q

what is a right afferent defect? aka optic nerve damage

A

no pupil constriction in both eyes when right eye stimulated with light
normal pupillary response in both eyes when left eye stimulated

91
Q

how do right afferent defects occur?

A

damage to optic nerve

92
Q

what is a right efferent defect? aka oculomotor nerve defect

A

no right pupil constriction when either left or right eye stimulated
left eye still constricts when right eye is stimulated

93
Q

how do right efferent defects occur?

A

damage to oculomotor nerve

94
Q

what is a swinging torch test used for?

A

to test relative afferent pupillary defects

95
Q

what are relative afferent pupillary defects?

A

partial pupillary response still present when damaged eye stimulated
so semi-damage to optic nerve

96
Q

how to test for deuteranomaly

A

ishihara test

97
Q

how would you test the back of someones eyes

A

fundoscopy

98
Q

what are the 3 types of retinal cells

A

photoreceptors
bipolar cells
retinal ganglion cells

99
Q

what are all of the types of eye movements

A

duction - one eye movement
version - both eyes move in same direction
vergence - bot eyes move in opposite directions
convergence - simultaneous adduction of both eyes

100
Q

what are the 2 speeds of eye movement

A

saccade - short fast bursts (reflex/predictive)

smooth pursuit - sustained slow movement (tracking(

101
Q

what is the optokinetic nystagmus reflex

A

when following a moving object, and it moves out of the field of vision, eye will snap back to the original viewing position
smooth pursuit then eyes reset to the middle using the fast reflex saccade

102
Q

what are the movements of the eye muscles

A 
SR - eye up
IR - eye down
LR - eye temporally
MR - eye nasally
IO - diagonally up and out
SO - diagonally down and out
103
Q

appearance of 3rd nerve palsy

A 
affected eye down and out (unopposed SO and LR) 
droopy eyelid (loss of levator palpebrae superioris)
dilated pupil
104
Q

appearance of 6th nerve palsy

A

affected eye unable to adduct
on relaxation is deviated inwards
double vision on gazing to the side of affected eye

105
Q

appearance of 4th nerve palsy

A

when looking towards unaffected eye, affected eye moves upwards (IO takes over from LR)

106
Q

what are the pupillary changes in the near response triad mediated by

A

sphincter pupillae contracts (circular smooth muscle) stimulated by parasympathetic nerves travelling with the oculomotor nerve

107
Q

what are the lens changes in the near response triad mediated by

A

ciliary muscle attached to the lens via suspensory ligament contracts
reduces tension on the suspensory ligaments, so the lens relaxes and becomes thicker, causing greater refractive power

108
Q

how does pupillary dilation occur

A

sympathetic stimulation to radial muscles causes them to contract
increases sensitivity to light

109
Q

describe the visual pathway

A

photoreceptors depolarise -synapse to bipolar cells depolarise - synapse to retinal ganglion fibres and travel out of eye as optic nerve
reach optic chiasm where nasal retinal fibres cross over, temporal dont, to form optic tracts
then synapse at lateral geniculate nucleus in thalamus
then travel via optic radiation to the primary visual cortex in occipital lobe

110
Q

where does the right visual field travel to in the brain

A

left hemisphere primary visual cortex

includes nasal retina from right eye and temporal retina from left eye

111
Q

how does the swinging torch test work

A

distinguishes relative and complete afferent defects
shine light in one eye, both pupils constrict, then quickly swing to other eye and hold it there
both pupils should constrict - if not, theres a relative afferent pupillary defect in the second eye tested

complete would be tested by eyes in isolation - not quickly changing lights

BRS Year 2 (67 decks)

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