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OD3 (S1&2) > DIS - Optic Nerve I - Week 10 > Flashcards

DIS - Optic Nerve I - Week 10 Flashcards

1
Q

What is one way of assessing optic nerve head size with a fundus photo?

A

You can expect the macula to be 2.5 disc diameters away from the optic nerve head for a normal size

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2
Q

How can the optic nerve head size be assessed using central retinal arteries and veins?

A

Expect 12 to 14 vein widths across the optic disc
Expect 10 to 20 arteriole widths across the optic disc

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3
Q

How can optic nerve head size be assessed using direct ophthalmoscopy?

A

Expect the disc to be one medium aperture size horizontally

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4
Q

How can a slit lamp be used to assess optic nerve head size? What correction factor is needed for a 90D lens?

A

Adjust slit width to the optic nerve head width and rotate, read size directly from the graticule
Correction factor - ~1.3 for 90D

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5
Q

What are four developmental issues that can occur affecting the optic nerve head? List the disease associated if applicable.

A

Embryonic cleft/fissure doesnt close
-coloboma
Optic nerve is underdeveloped
-optic nerve hypoplasia
Hyaloid doesnt disappear
Normal myelination doesnt stop before the eye
-medullated nerve fibres

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6
Q

What tissue does coloboma often involve? what may it be associated with?

A

Typically involves tissue along inferior orientation
May be associated with chromosomal defects

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7
Q

List three types of coloboma.

A

Retina/choroid
Optic nerve
Mix of the above

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8
Q

How does the retina appear with retina/choroidal coloboma and what happens to visual fields here? What is vision like? What is there a risk of?

A

White sclera visible through ectatic/thin tissue
Visual field loss over affected region
Vision usually ok if fovea spared
Risk of retinal detachment
-rhegmatogenous due to thin tissue

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9
Q

What is the optic nerve head size like with isolated optic nerve coloboma and how does this affect the blindspot? What is the blood vessel pattern like?

A

Larger than usual size
Enlarged blindspot on VF testing
Unusual blood vessel patterns

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10
Q

Up to what distance can peripapillary changes be seen in isolated optic nerve coloboma?

A

2DD

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11
Q

Is vision often affected in isolated optic nerve coloboma?

A

Yes, but veries from 6/7.5 to hand movements

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12
Q

Is there a risk of retinal detachment with isolated optic nerve coloboma?

A

Yes
-non-rhegmatogenous due to subretinal fluid

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13
Q

What is the optic disc like in morning glory syndrome and what are the blood vessels like? Is it easy to distinguish arterioles from venules?

A

Enlarged, funnel-shaped cavity of the optic disc
Anomalous blood vessels radiating circumferentially
Difficult to distinguish arterioles from venules

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14
Q

What is a glial plug and what is it seen in?

A

Tuft of glial tissue obscuring central cup in morning glory syndrome

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15
Q

What is the peripapillary region like in morning glory syndrome?

A

Pigment abnormality
-hyper and hypo pigment clumps

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16
Q

What is vision and prognosis like for morning glory syndrome?

A

Poor vision and prognosis

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17
Q

What pattern do blood vessels have in morning glory syndrome?

A

They radiate outwards like flower petals

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18
Q

Do congenital and acquired optic disc pits appear similar?

A

Yes

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19
Q

Define congenital optic disc pit.

A

Herniation of dysplasic retina extending posteriorly through a defect in the lamina cribrosa

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20
Q

Are congenital optic disc pits round or oval?

A

Can be either

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21
Q

Where can congenital optic disc pits most often be found (2)?

A

Commonly temporal, mostly at margin

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22
Q

What disease can congenital optic disc pits occur with?

A

Optic disc coloboma

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23
Q

Are optic disc pits progressive or non-progressive? What can happen with associated retinal abnormalities?

A

Optic disc pits are non-progressive
The associated retinal abnormalities may progress

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24
Q

What proportion of patients with optic nerve pits have retinal detachment and which type? Where does it occur?

A

2/3rds have non-rhegmatogenous detachment
-could be at the macula or close to it

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25
Q

What may contribute to the risk of retinal detachment in optic nerve pits?

A

Frequent retinoschisis-like separations

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26
Q

What is a retinoschisis-like separation?

A

Separation of retinal layers near the macula

27
Q

Define complicated coloboma (3).

A

Optic nerve head, retina/choroid ± iris involvement

28
Q

Complicated coloboma has a risk of which type of retinal detacment?

A

Both

29
Q

What may management require if complicated coloboma has iris involvement (2)?

A

Cosmetic contact lens for artificial pupil
Glare protection

30
Q

What should be considered if one eye has coloboma (2)?

A

Treatment of anisometropic amblyopia
Ocular realignment surgery if strabismic

31
Q

When should coloboma be referred and to who?

A

Refer to vitreoretinal ophthalmologist for:
-retinal detachment
-progression of schisis-like separation
-any presumed subretinal fluid
-vitreoretinal traction, especially macular
-urgency relative to risk of central visiond loss

32
Q

List two reasons why a referral to a GP should be considered for coloboma.

A

MRI for brain abnormalities
Association with chromosomal defects

33
Q

What is the most common congenital optic nerve anomaly and what is it due to?

A

Optic nerve hypoplasia
Underdevelopment of optic nerve fibres

34
Q

Is there a genetic component for optic nerve hypoplasia?

A

Yes

35
Q

List 6 possible maternal insults that can cause optic nerve hypoplasia.

A

Diabetes
Alcohol abuse
Illicit drug use (LSD)
Anticonvulsants (phenytoin)
Foetal or maternal infection (hepB/CMV)
Smoking

36
Q

Which of the two are a risk factor for optic nerve hypoplasia:
Birth from a young mother
Birth from an old mother

A

Young mother

37
Q

List four signs of optic nerve hypoplasia.

A

Low number of nerve fibres
Pale and small optic nerve head
Small neuroretinal rim
Thin RNFL

38
Q

What can optic nerve hypoplasia be confused with? Compare them (2).

A

Optic atrophy
-hypoplasia is non-progressive
-vasculature often appears very large due to hypoplasic disc

39
Q

Is optic nerve hypoplasia progressive or non-progressive?

A

Non-progressive

40
Q

List the two types of optic disc hypoplasia and what you expect it to look like. Which is associated with a tilted disc?

A

Total disc hypoplasia
-pale/pigmented peripapillary halo
Sectoral disc hypoplasia
-crescent of pallor
-associated with tilted disc

41
Q

What is a halo or crescent on a fundus photo?

A

The bare, exposed sclera where the normal-sized disc should have extended

42
Q

Which type of optic disc hypoplasia is the double ring sign seen in and what is it?

A

Total disc
-pale/pigmented peripapillary halo

43
Q

What can be seen in ~10% of children to diabetic mothers with poor control? Particularly what type of children (3)?

A

Superior segmental optic nerve hypoplasia
-particularly in premature females of low birth weight

44
Q

Can optic nerve hypoplasia be an isolated finding or does it always have an association?

A

Can be an isolated finding, but is frequently part of a syndrome

45
Q

Is optic nerve hypoplasia typically uni- or bilateral?

A

Bilateral

46
Q

List four times you would refer optic nerve hypoplasia.

A

Low vision and occupational therapy services
Infants who may require examination with sedation/general anaesthesia
MRI of intracranial visual pathways
GP for neurodevelopmental and endocrinologic deficiency

47
Q

What is bergmeisters papilla?

A

Persistent/remnant hyaloid at the ONH

48
Q

What is a remnant glia?

A

cellophane sheet or cotton ball of glial tissue overlying blood vessels near the ONH

49
Q

What is a mittendorf dot and where is it typically located?

A

Small opacity on the posterior lens capsule
It is the anterior attachment of the hyaloid artery

50
Q

What is persistent foetal vasculature syndrome, what is globe formation like, what is it also known as, and is it uni- or bilateral?

A

Aberant globe formation (smaller, white eye)
Retention of primary vitreous and hyaloid
Often unilateral
-also known as persistnet hyperplasic primary vitreous

51
Q

What is often seen in the affected eye with persistent foetal vasculature syndrome?

A

Cataract

52
Q

How should floaters be considered with a suspected case of persistent foetal vasculature syndrome?

A

Floaters may be common - note baseline

53
Q

Does persistent foetal vasculature syndromehave any effect on vision?

A

Typically no

54
Q

Which population is persistent/remnant hyaloid most common in?

A

Premature infants

55
Q

Does persistent foetal vasculature syndrome require referral for management? What about management for unilateral cases?

A

Referral for surgery
Amblyopia management for unilateral cases

56
Q

Where does myelination begin in the visual pathway and where is it supposed to stop?

A

Starts in the LGN, stopping at the lamina

57
Q

Describe two types of myelination that enters the eye in terms of attachment and their percentages.

A

80% continuous with the disc
Rest are detached from the disc

58
Q

How do myelinated/medullated fibres appear?

A

Feathery white, visible, distinct fibres

59
Q

Do myelinated/medullated fibres affect the blindspot?

A

Possible enlarged blindspot visual field defect

60
Q

What should you do if you suspect myelinated/medullated fibres? Give two differentials.

A

Differentiate from other white things
-cotton wool spots appear softer, more diffuse
-vasculitis appears dirtier (i.e. with haemorrhages)

61
Q

Do myelinated/medullated fibres affect vision? What should be done for management?

A

Typically no effect
-management can be routine eye exam
-record baseline

62
Q

Can congenital myelinated nerve fibres ever disappear? Explain.

A

They can, with multiple sclerosis or optic neuropathy

63
Q

What do congenital optic disc anomalies have in common (2)?

A

Non-progressive
Potential for associated retinal abnormalities that progress and therefore need monitoring

64
Q

What two things does management of congenital optic disc anomalies depend on?

A

Unilateral or bilateral
Systemic associations

OD3 (S1&2) (114 decks)

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