Brainscape's Knowledge GenomeTM

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


See full index

Ocular Anatomy > Optic Nerve (Q3) > Flashcards

Optic Nerve (Q3) Flashcards

CN are in nerve deck, Hematomas are in vasculature

1
Q

What do we call the most anterior part of the optic nerve?

A

Optic disc

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

The colour (or lack thereof) of the ONH is due to the absence of …

A

retinal pigment epithelium

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

Which side of retina is the ONH located and how many degrees from fixation?

A

Located in the nasal retina, 15 degrees from fixation

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

T/F: ONH acts as a physiological blind spot in visual field tests

A

True

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

In an evaluation of the ONH, we should examine…

A

margins, rim tissue, disc size, C/D ratio, depth, blood vessels, and insertion of the nerve

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

List the sides of the rim tissue as thickest to thinnest

A

Inferior, Superior, Nasal, Temporal (ISNT Rule)

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

What is the average optic disc size (in mm)?

A

1.9mm vertically and 1.7mm horizontally

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

What measurement is considered a small disc size (in mm)?

A

<1.5mm

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

What measurement is considered a large disc size (in mm)? What might this condition be called?

A

> 2.2mm, Megalopapilla

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

What are the correction factors for measuring disc size using a +60D lens? +78D lens? and +90D lens?

A

1.0 (for +60D lens), 1.1 (for +78D) and 1.3 (for +90D lens)

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

What is optic nerve hypoplasia?

A

A congenital, pathologic condition in which the optic nerve head is underdeveloped

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

The cup-to-disc ratio indicates the diameter of the cup expressed as a fraction of the diameter of the optic disc and is given in increments of…

A

0.05

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

T/F: Cup-to-disc ratio is most accurately determined stereoscopically

A

True

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

T/F: A deep physiological cup makes it harder to judge a C/D ratio

A

False, a deep cup is easier to evaluate C/D ratio compared to a shallow cup which is more difficult; you may need to use the appearance of the blood vessels to judge.

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

Is a malinserted (insertion not perfectly perpendicular) ONH pathologic or not? And what visual condition is it usually associated with?

A

Not pathologic, associated with moderate to high myopia

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

What is a choroidal crescent?

A

A dark area by the ONH caused by an absence of the RPE/retina, allowing the underlying choroid to be visible

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

What is a scleral crescent?

A

A white area next to the ONH caused by the absence of the RPE/retina and choroid layers, allowing the underlying white sclera to be visible

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

Are choroidal/scleral crescents pathologic? And are they included in judging C/D ratio?

A

Not pathologic, and not included in rim tissue when judging C/D ratios

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

What are some other common ONH findings?

A

Disc hemorrhages, ONH drusen, notches in rim tissue, collaterals, laminar dots, etc.

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

The optic nerve is composed of bundles of axons carrying signals from the retina to the brain. Where are the cell bodies of these axons located? And what layer is also formed by these axons?

A

Cell bodies are in the ganglion cell layer of the retina, and the axons also form the nerve fibre layer before coming together at the optic nerve

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

Which side of the optic disc do the macular fibres enter and what is this bundle of nerve fibres also referred to as?

A

Macular fibres enter at the temporal disc and are also referred to as the papillomacular bundle

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

T/F: All 3 layers of the meninges fuse together and become continuous with the sclera

A

True

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

What is the longest segment of the optic nerve?

A

the intraorbital segment

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

What is the shortest segment of the optic nerve?

A

the intraocular segment

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

What is the name for the sieve-like interwoven collagen fibrils forming canals through which the optic nerve bundles pass through in the intraocular segment?

A

the lamina cribrosa

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

Which is the only segment of the optic nerve that is non-myelinated?

A

the intraocular segment

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

Which EOMs attach to the intraorbital segment of the optic nerve?

A

the superior rectus and medial rectus

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

Which structures of the brain are surrounding the intracranial portion of the optic nerve (leading up to the optic chiasm)?

A

Superiorly - olfactory tract, anterior cerebral artery
Medially - sphenoid sinus
Inferiorly - internal carotid artery, middle cerebral artery, pituitary gland

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

What is the name for a proliferation of meningeal cells of the intraorbital and intracanalicular optic nerve? What are the symptoms?

A

Optic nerve sheath meningioma. Affect F>M (40-50yrs of age) gradual painless vision loss usually in one eye, optic nerve head edema or atrophy, and/or optociliary shunt vessels (collaterals)

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

Which structures supply blood to the intraocular (pre-laminar and laminar) portions of the optic nerve?

A

The circle of Zinn, formed by the short posterior ciliary arteries

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

Which vessels supply blood to the intraorbital portion of the optic nerve?

A

The central retinal artery and pial vessels

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

Which arteries supply blood to the intracranial portion of the optic nerve?

A

The ophthalmic, anterior cerebral, anterior communicating, and internal carotid arteries

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

What are the possible symptoms of a pituitary adenoma?

A

Blurred vision, headache, diplopia, colour desaturation, visual field defect (bilateral hemianopsia), optic atrophy

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

Can visual field defect improve after removal of a pituitary tumour?

A

Depends on the amount of optic nerve damage/atrophy, it may improve if the tumour is caught early!

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

The Circle of Willis is an anastomosis of which arteries/circulations?

A

Anterior circulation: internal carotid arteries, and posterior circulation: basilar, vertebral arteries

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

A patient had an optic tract lesion due to a stroke which caused a left hemianopsia in his visual field testing, which side of his brain was affected?

A

Right side

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

What is the name of the nuclei where the axons of the ganglion cells synapse?

A

Lateral geniculate nucleus, in the thalamus

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

Which layers of the LGN are magnocellular and which are parvocellular? What are the layers in between these 6 layers called?

A

Layers 1-2 are magnocellular, layers 3-6 are parvocellular. Koniocellular layers are located in between all 6 layers

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

Which layers of the LGN do contralateral (crossed) fibres of the optic tract synapse in?

A

Layers 1,4,6

40
Q

Which layers of the LGN do ipsilateral (uncrossed) fibres of the optic tract synapse in?

A

Layers 2,3,5

41
Q

The axons that project from the LGN to the primary visual cortex (V1) are called…

A

optic radiations

42
Q

The visual cortex is divided into an upper and lower portion by the calcarine fissure, what are these gyri called and which part of the retina do the information they process come from?

A

Upper - Cuneus gyrus: processes info from superior retina (inferior visual field)
Lower - Lingual gyrus: processes info from inferior retina (superior visual field)

43
Q

V1 processes basic stimulus, which centers make up the extrastriate cortex that processes more complex information?

A

V2-V5, on lateral aspect of occipital cortex

44
Q

Which layer of V1 receives visual input from the LGN?

A

Layer 4

45
Q

Which layer of V1 provides inhibitory feedback to the LGN?

A

Layer 6

46
Q

What structure supplies blood to the optic chiasm?

A

the Circle of Willis

47
Q

Which arteries supply blood to the optic tract?

A

Anterior choroidal artery

48
Q

Which arteries supply blood to the LGN?

A

Anterior choroidal, and posterior cerebral arteries

49
Q

Which arteries supply blood to the optic radiations?

A

Anterior choroidal, middle cerebral, and posterior cerebral arteries?

50
Q

Which arteries supply blood to the visual cortex?

A

Middle cerebral, and posterior cerebral arteries

51
Q

Which structures of the visual pathway are supplied by the anterior choroidal artery?

A

Optic tract, LGN, and optic radiations

52
Q

Which structures of the visual pathway are supplied by the posterior cerebral arteries?

A

LGN, optic radiations, visual cortex

53
Q

Which structures of the visual pathway are supplied by the middle cerebral arteries?

A

Optic radiations, and the visual cortex

54
Q

T/F: about 5,000 ganglion cells are lost per year

A

True

55
Q

T/F: myelinated retinal nerve fibres are pathologic

A

False, they are not pathologic

56
Q

Most retinal neurons use graded potentials or action potentials?

A

Graded, however ganglion cells generate action potentials

57
Q

T/F: Inside of axon is more negative than outside environment

A

True; Na+ flows in, resulting in depolarization

58
Q

An example of a disease caused by a loss of myelin, resulting in reduced conduction velocity

A

Multiple sclerosis

59
Q

Periventricular white matter lesions/plaques in the brain almost definitively mean which disease?

A

Multiple sclerosis

60
Q

What is Uhthoff’s phenomenon in MS patients?

A

A loss of conduction due to changes in body temperature, such as when exercising or having a hot shower, possibly more numbness or vision problems noticed at these times

61
Q

What is Lhermitte’s sign in MS patients?

A

an electric shock-like sensation that occurs with flexion of the neck

62
Q

What is Pulfrich’s phenomenon in MS patients?

A

An altered perception of motion usually because one eye is affected more than the other

63
Q

What are the ocular symptoms of MS?

A

pain on eye movement, diplopia, flashing lights (phosphenes)

64
Q

What are the ocular signs of MS?

A

ONH edema or pallor, optic neuritis, varying degrees of vision loss, APD, VF defects, loss of colour vision, decreased contrast sensitivity, etc.

65
Q

What is an astrocytoma?

A

A slightly elevated, yellow-white retinal mass due to astrocyte proliferation. Rare, but when found is usually in a younger patient and can potentially be malignant

66
Q

What are NG2-glia?

A

A new class of glial cells, thought to be oligodendrocyte progenitor cells that can differentiate into other cell types depending on the environment

67
Q

What are the four main signs of optic nerve damage?

A

VA loss, VF loss, pallor/atrophy, and excavation (loss of rim tissue)

68
Q

What are the risk factors of optic nerve injury due to ischemia?

A

age, hypertension, diabetes mellitus, migraine headaches, sleep apnea, and tobacco use

69
Q

What are the signs and symptoms of optic nerve injury due to ischemia?

A

sudden, unilateral, painless vision loss

clinical signs: ONH edema/atrophy, and hemorrhages

70
Q

What conditions may cause an optic neuropathy by compression?

A

tumours (ex. pituitary adenoma), aneurysms, enlarged EOMs

71
Q

What is the definition of papilledema?

A

Optic disc edema caused by elevated intracranial pressure

72
Q

What are the common symptoms of papilledema?

A

can be asymptomatic, or vision loss, changes in colour vision, headache, nausea, vomiting, diplopia, etc.

73
Q

How should you document a case of swollen optic nerves before an elevated intracranial pressure is proven to be true?

A

“bilateral disc edema”, NOT papilledema unless ICP is proven to be elevated

74
Q

What is the most common cause of optic neuropathy?

A

Glaucoma, the loss of ganglion cell axons

75
Q

How can we measure a glaucoma progression objectively?

A

Using OCT scans of the RNFL thickness over time

76
Q

In glaucoma progression, which clinical sign usually is seen earlier compared to the others?

A

Earliest is usually changes in RNFL thickness, then disc changes (C/D ratios), and then visual field changes in later stages

77
Q

What are the signs and symptoms of optic atrophy

A

reduced VA, dyschromatopsia, visual field defects, afferent pupillary defect, etc.

78
Q

Optic atrophy due to damage anterior to the chiasm is usually seen unilaterally or bilaterally?

A

Unilateral

79
Q

Optic atrophy due to damage posterior to the chiasm is usually seen unilaterally or bilaterally?

A

Bilateral

80
Q

What is a neurotrophin?

A

a regulatory factor that induces survival, development, and function of neurons; implicated in neurodegenerative diseases such as Alzheimer’s and possibly glaucoma

81
Q

Which neurotrophin has the greatest influence on the optic nerve?

A

BDNF - brain-derived neurotrophic factor

82
Q

Which cells’ survival does BDNF enhance?

A

Retinal ganglion cell survival after optic nerve injury, preserving structural integrity and visual responsiveness (therapeutic possibilities!)

83
Q

Which of the non-glaucomatous causes of optic atrophy involves edema, primary or secondary?

A

Secondary (nerve becomes swollen and then recedes and then atrophy occurs)

84
Q

What are the common causes of primary optic atrophy?

A

bilaterally - hereditary reasons, or nutritional/toxic cases

unilaterally - trauma

85
Q

What are the common causes of secondary optic atrophy?

A

bilaterally - papilledema, compression

unilateraly - ischemia, occlusion, compression

86
Q

At what amount of time is an average of 50% of the RNFL lost after an injury?

A

56 days after injury

87
Q

Perfusion pressure definition

A

how easily blood can pass through a given tissue, it is the difference between the pressure of the blood flow entering and leaving the eye

88
Q

Perfusion pressure of the eye, equation

A

mean arterial pressure of the arteries entering the eye is around 65 mmHg and the pressure in the episcleral veins leaving the eye is around 15 mmHg, so the perfusion pressure of the eye is approximately 50 mmHg.

89
Q

Ocular perfusion pressure =

A

OPP = diastolic BP - IOP

90
Q

What does OPP tell us for glaucoma patients?

A

pts with a low OPP are 1.5x more likely to develop progresisve optic neuropathy secondary to ischemia

91
Q

What is the relationship between IOP and OPP?

A

if IOP decreases, OPP increases

if IOP increases, OPP decreases

92
Q

What is the relationship between OPP and diastolic BP?

A

if diastolic BP decreases, OPP decreases

93
Q

autoregulation

A

the process by which blood vessels alter their diameter (in the absence of neural control) in order to increase or decrease resistance to blood flow (pericytes are most likely responsible for this in the retina and optic nerve)

94
Q

transmural pressure

A

describes the pressure across the blood vessel wall and is determined by subtracting the pressure outside the vessel from the pressure inside the vessel

95
Q

critical closing pressure

A

the pressure at which the blood vessel collapses and blood flow stops

96
Q

What is the immediate threat to vision in an acute angle closure?

A

CRAO! the pressure in the eye causes the retinal vessels to autoregulate until they reach their critical closing pressure at which point a CRAO would occur to the CRA

Ocular Anatomy (12 decks)

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