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Block 8 > Ocular Lab 8 Questions > Flashcards

Ocular Lab 8 Questions Flashcards

1
Q

Difference between ora serrata and peripheral retina

A

Ora serrata –> end of the retina

Peripheral retina –> outer part of retina that TERMINATES at ora serrata

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2
Q

How wide is the macula

A

5mm

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3
Q

Where the retina starts to make changes and slope

A

Fovea

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4
Q

The very center of the fovea

A

Foveola

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5
Q

What is the cup to disc ratio

A

Compares the diameter of the cup to diameter of entire disc

-> assess neuroretinal rim thickness over time

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6
Q

How long is the intraocular part of ON

A

1.5 mm

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7
Q

How long is the intraorbital part of ON

A

25mm

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8
Q

How long is the intracanalicular part of ON

A

5 mm

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9
Q

How long is the intracranial part of ON

A

10mm

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10
Q

How long is the entire ON in length

A

4-5 cm

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11
Q

Glial plaque (astrocytes) that line the optic cup

A

Meniscus of Kuhnt

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12
Q

Peripheral continuation of meniscus of Kuhnt that lines surface of neuroretinal rim

A

Inner limiting membrane of elschnig

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13
Q

Formed by footplates of muller cells, continuous with inner liming membrane of elschnig

A

Internal limiting membrane of retina

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14
Q

Glial tissue that separates outer retina from bundles of ON fibers

A

Intermediary tissue of Kuhnt

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15
Q

Collagen separating choroid from bundles of ON fibers

A

Border tissue of elschnig

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16
Q

Glial tissue situated between border tissue of elschnig and bundles of ON fibers. it merges with intermediary tissue of kuhnt

A

Border tissue of jacoby

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17
Q

Remnant of meniscus of Kuhnt tissue surround the hyaloid vasculature during development

A

Bergmeister’s papilla

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18
Q

Size of small discs vertical diameter

A

<1.5 mm

19
Q

Size of large discs vertical diameter

A

> 2.2 mm

20
Q

Medium sized vertical diameter of optic disc

A

1.9mm

21
Q

Where does the ON become myelinated

A

Just posterior to lamina cribrosa

22
Q

What is the ON myelinated

A

For insulation, protection and to speed up travel/transmission to the brain

23
Q

What is the prelaminar diameter of ON

A

1.5mm

24
Q

What is the post laminar diameter of ON

A

3-4mm

25
Q

Why is there a difference in diameter between pre/post laminar regions of ON

A

Because of myelin being laid down behind lamina cribrosa

26
Q

What are the meningeal layers of the ON continuous with

A

The meningeal layers of the brain

27
Q

Bilateral swelling of disc caused by elevated intracranial pressure within the subarachnoid space

A

Papilledema

28
Q

Presents with indistinct margins of disc, engorged vessels, small peripapillary hemorrhages and loss of spontaneous venous pulsation

A

Papilledema

29
Q

Where does the intracanalicular portion of ON pass through and what travels with it

A

Lesser wing of sphenoid bone via optic canal with ophthalmic artery

30
Q

How does the ophthalmic artery sit in relegation to ON when passing through optic canal in lesser wing of sphenoid bone

A

Inferolateral to the ON

31
Q

How far from the globe does the CRA pierce the ON

A

1.25 cm

32
Q

What is the lamina cribrosa and adjacent pail plexus supplied by

A

Arterial circle of zinn-haller

33
Q

What supplies the arterial circle of zinn-haller

A

Short posterior ciliary arteries

34
Q

Why does the macula look different from the rest of the retina

A
  • It only has densely packed cones, no rods
  • sloped bc of henle fibers
  • avascular
  • more than one RGCL
  • appears more pigmented bc less layers covering the RPE
  • high levels of carotenoids
35
Q

Why does the RNFL run parallel to retina

A
  • axons of gang cells have to run this way to converge into ON
  • inline bipolar cells, they do not synapse locally, so their axons are different
36
Q

Why ON becomes thicker once the NFL passes through the lamina cribrosa

A

Bc of myelination

37
Q

3 main causes of papilledema

A
  • inc CSF causing disc to be pushed forward
  • veins re engaged bc blood cannot leave eye
  • obstruction of axonal flow
38
Q

Total blood supply to the ON beginning with ICA

A

ICA –>. Ophthalmic a –> CRA –> capillaries and short posterior a

39
Q

Where does the CRA branch

A

In the intraorbital region after the optic canal

40
Q

Why are diabetics susceptible to ON damage

A

Bc the capillaries can be easily damaged

41
Q

Why is the optic disc taller than it is wide

A

Bc of ISNT rule

- more gang cells coming into top and bottom

42
Q

Why is the nasal side of ON thicker than temporal region

A

Temporal only gets in from from macular but nasal gets info form most of peripheral retina

43
Q

With the isnt rule, what is thickest/thinnest

A

I - thickest

T - thinnest

Block 8 (11 decks)

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