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Ocular Block 8 > Optic Nerve > Flashcards

Optic Nerve Flashcards

(104 cards)

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1
Q

Where do the ganglion cell bodies reside

A

Retinal ganglion cell layer

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2
Q

Where do the dendrites of the ganglion cells reside

A

IPL

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3
Q

Where do the axons of the ganglion cells reside

A

RNFL

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4
Q

How many retinal ganglion cells are there

A

1.2 to 22 mill

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5
Q

These are the output cells of the retina that convey all of the processed visual information to the brain

A

Retinal ganglion cells

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6
Q

How is the RNFL formed

A

By the axons of the retinal ganglion cells.

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7
Q

What is the average diameter of optic nerve fibers

A

1 micron

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8
Q

Where is the deep plexus from CRA

A

INL

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9
Q

Where is the superficial plexus of CRA

A

RNFL

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10
Q

A nerve fiber tract of the central nervous system

A

Optic nerve

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11
Q

Why is the optic nerve prone to many of the same neurological diseases as the brain

A

It is a nerve fiber tract of the CNS

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12
Q

What kind of neurological diseases can affect the optic nerve

A

All of them really, but especially demyelinating diseases such as MS

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13
Q

What are the different parts of the optic nerve

A
  1. Intraocular
  2. Infraorbital
  3. Intracanalicular
  4. Intracranial
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14
Q

What is the approxiamte length of the optic nerve

A

4-5cm

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15
Q

What part of the optic nerve do you see on a fundus exam

A

Intraocular

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16
Q

What part of the optic nerve is the longest

A

Infraorbital

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17
Q

What part of the optic nerve is when it passes through the optic canal and before it meets at the chiasm?

A

Intracanalicular

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18
Q

What part of the optic nerve is where it joins at the optic chiasm

A

Intracranial

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19
Q

What is the smallest part of the optic nerve

A

Intraocular part of the optic nerve

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20
Q

What are some things you look at when looking at the ONH

A 
Size 
Shape
Color
Vessels
Border, contour
Lamina cribrosa
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21
Q

Shape of the optic disc

A

Oval shape and is longer in the vertical dimension vs horizontal

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22
Q

What is the diamter of the ONH in the vertical direction

A

1.9mm

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23
Q

What is the diamter of the ONH in the horizontal direction

A

1.5mm

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24
Q

How is the optic cup displaced compared to the disk

A

Temporally

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25
Optic cup and nerve fibers
The optic cup is devoid of nerve fibers
26
Where can you sometimes see the lamina cribrosa
Optic cup
27
Contains the nerve fibers and it located between the margin of the optic disk and cup
Neuroretinal rim
28
How does the thickness of the neuroretinal rim go
Follows the ISNT rule - inferior should be thickest - temporal should be thinnest
29
Compares the diamter of the cup with the overall diameter of the optic disc and is used to assess changes in neuroretinal rim thickness over time
Cup to disc ratio
30
What side of the cup do the CRA/CRV emerge
Nasal side
31
Is the CRA or the CRV usually more nasal
Artery
32
What are the two different portions of the intraocular portion of the opticnerve
Prelaminar | Laminar/scleral
33
What is considered the prelaminar part of the intraocular portion of the optic nerve
Retinal layer | Choroidal layer
34
What is considered laminar/scleral portion of the intraocular portion of the optic nerve
Scleral ayer (lamina cribrosa)
35
What does glaucoma do to lamina cribrosa
Causes the lamina to pinch the nerves that are going through it and kills them
36
PR and the optic nerve
There are no PR in the ONH so this is a blind spot
37
Retinal layer of the pre-laminar part of the intraocular portion of the optic nerve
The optic disc is located in the retinal layer because it is the axonal fibers of the retina ganglion cells that converge to form it
38
The choroidal layer of the pre laminar layer of the intraocular portion of the optic nerve
At the level of the choroidal tunic. The lamina cribrosa begins in the outermost portion of the choroidal layer of the optic nerve and continues into the scleral layer of the optic nerve
39
What are the glial borders around hte optic nerve
- meniscus of Kuhnt - ILM of Elschnig - border tissue of Elschnig - border tissue of jacoby - intermediate tissue of Kuhnt - ILM of retina
40
What are the glia cells involved in the glial border around the optic nerve
Astrocytes. There are no muller cells here because there is no retina here
41
What are the glial borders around the optic nerve that are considered to be retinal layer
- meniscus of Kuhnt - ILM of Elschnig - ILM of retina - intermediary tissue of kuhnt
42
Glial plaque (astrocytes) that lines the optic cup
Meniscus of Kuhnt
43
Peripheral continuation of meniscus of Kuhnt that lines surface of neuroretinal rim
ILM of Elschnig
44
Formed by the footplates of muller cells, continuous with ILM of Elschnig
ILM or retina
45
Glial tissue that separates outer retina from bundles of optic nerve fibers
Intermediary tissue of Kuhnt
46
What are the glial borders of the choroidal layer of the intraocular portion of the optic nerve
Border tissue of Elschnig | Border tissue of jacoby
47
Collagen separating choroid from bundles of optic nerve fibers
Border tissue of Elschnig
48
Glial tissue situated between border tissue of Elschnig and bundles of optic nerve fibers. It merges with intermediary tissue of Kuhnt
Border tissue of jacoby
49
Remnant of meniscus of Kuhnt tissue surrounding the hyaloid vasculature during development
Bermeisters papilla
50
Optic cup size at birth
Is related to disc size and resorption of glial tissue surrounding hylaoid vasculature
51
What is to be said about the cups of large discs
Large discs have large cups. Don't always assume a large cup is glaucomatous, always make sure its not just a large cup
52
Scleral layer of the laminar portion of hte optic nerve
The scleral layer is continuous with the scleral tunic of the eyeball and is the layer in which the lamina cribrosa resides
53
What layer does the lamina cribrosa reside
Scleral layer of the laminar portion of the optic nerve
54
Myelination of optic nerve
There is only myelin post-laminar, oligodendrocytes lay down myelin here but none in the eye
55
Myelin in the eye
Not normally any myelin in the eye, but some people are born with a little bit in there and you can see it on a fundoscopic exam. Won't affect vision too much, just document and move on
56
Why does the diameter of the retrobulbar optic nerve increase
Myelin
57
Astrocytes in retrobulbar optic nerve
Form thick columns that keep the axonal fibers organized into bundles in the optic nerve. Can be IDed on histology because their nuclei form long columns between the axonal bundles
58
How long is the infraorbital portion of the optic nerve
25mm
59
Where is the intraorbital portion of the optic nerve
From the sclera to the apex of the orbit
60
What is responsible for the increase in size of the optic nerve from 1.5mm to 3-4mm in diameter in the intraorbital portion of the optic nerve
Myelin
61
Where does the optic nerve pass through at the apex of the orbit
Passes through the optic canal in the lesser wing of the sphenoid
62
Where is the optic nerve sheath?
Parts of the optic nerve that reside outside of the eye
63
What is the optic sheath comprised of
Dura mater, arachnoid mater, and pia mater All three of these layers fuse with the retina CSF is contained within the subarachnoid mater
64
Bilateral swelling of the optic disc caused by elevated ICP within the subarachnoid space
Papilledema
65
How does papilledema present
Indistinct margins of the disc, engorged venous blood vessels, small peripalliary hemorrhages, and loss of spontaneous venous pulsation
66
Why is it that the veins are the vessels to get engorged in papilledema
More likely to become damaged because they are thinner than arteries. They cant get the blood back out of the retina so it is stuck in there
67
What causes venous pulsation
Pressure differential between IOP and ICP
68
When is venous pulsation important
When you have documented that someone has SVP, but at some point do not have it. Indicative of increased ICP
69
What is the difference between papilledema and pseudopapilledema
Papilledema is cause by high ICP Pseudopapilledema does not have increased ICP, but it is more ONH drusen that makes the ONH appear odd
70
Cause of pseudopapilledema
Buried disc drusen. These small tumors develop within the substance of the nerve tissue and can lead to an elevated disc, they also may lead to a loss of VF or central acuity
71
What is the difference in appearance of papilledema and pseudopapilledema
Pseudopapilledema has defined borders and papilledema does not. Also pseudo has no venous engorgement
72
How long is the intrcanalicular portion of the optic nerve
5mm
73
How does the intrcanalicular portion of the optic nerve pass
Through the lesser wing of the sphenoid bone via the optic canal and is accompanied by the ophthalmic artery
74
How does the ophthalmic artery sit relative to the optic nerve
Inferolateral
75
What is the subarachnoid space of the optic nerve continuous with
The subarachnoid space of the brain
76
Where does the central retinal artery pierce the optic nerve
12-15mm from the sclera
77
How does the ciliary ganglion sit relative to the optic nerve
Just lateral to it
78
Where does the optic nerve reside within in the apex of the orbit
Common annular tendon of Zinn
79
What are the nerves outside of the annular tendon of zinn
Lacrimal nerve Frontal nerve Trochlear nerve
80
What nerves are within the annular tendon of Zinn
Superior oculomotor nerve Nasociliary nerve Inferior oculomotor nerve Abducens nerve Optic nerve
81
How long is the intracranial portion of the optic nerve
10mm
82
What does the optic nerve do once it leaves the optic canal
Passes within the subarachnoid space of the brain where it will merge with nerve fibers from the contralateral optic nerve at the optic chiasm
83
Where is the optic chiasm located
Floor of the 3rd ventricle
84
What is the branch of the ICA that supples the optic nerve
Ophthalmic artery
85
How does the central retinal artery run
Along the optic nerve, then at about 1.25cm behind the eyeball through lamina cribrosa
86
What does the pia do for the optic nerve
Supports it
87
What is the retinal layer of the optic disc supplied by
Retinal capillaries (non fenestrated)
88
What does the choroidal layer of the optic nerve get its blood supply from
Only the peripheral portion of the lamina choroidalis receives some nutrition via diffusion from the surrounding choroidal vasculature
89
What are the lamina cribrosa and adjacent pial plexus supplied by
The arterial circle of Zinn-Haller, which is supplied by the short posterior ciliary arteries
90
What is the connection between the retinal and posterior ciliary arterial systems
None
91
Venous drainage of the optic nerve
Central retinal vein
92
Where does the central retinal artery enter the eye
Through an aperture in the lamina cribrosa of the optic disc
93
How is the CRA positioned
Slightly nasal in the nerve and nasal to the central retinal vein
94
Why is it important to notice that the vessels emerge nasally in the optic disc
Some disorders can nasalize the vessels, meaning they will be pushed much more nasally than normal
95
Weiss' ring
Vitreous has pulled away from the optic nerve
96
ISNT rule
Inferior neuroretinal rim is thickest and the temporal neuroretinal rim is the thinnest
97
Tilted disc
Some people have an obliquely placed optic nerve, which means that certain parts of the disc are actually much flatter than others
98
Scleral crescent
Choroid and RPE don't reach all the way to ONH margin, sclera showing through, whitish
99
Peripapillary crescent
RPE stops before the choroid does, appears darker
100
What happens if there is a disc with no cup
Nothing, can be completely normal. Just document
101
When is it OK to have a large cup
When you have a large disc. As long as it follows the ISNT rule, its fine
102
How can you tell if someone is glaucomatous or if they have large cups
Large cups will follow the ISNT rule | -glaucomatous will not follow the ISNT rule and you can see the lamina cribrosa through it
103
What is one of the earliest signs of glaucoma
Inferior notch
104
What would cause pallor in one eye but not the other
Ischemic optic neuropathy in that one eye or some sort of compression on the optic nerve of that eye

Ocular Block 8 (6 decks)

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