[13] Anterior Ischaemic Optic Neuropathy Flashcards

1
Q

What is anterior ischaemic optic neuropathy?

A

A medical condition involving loss of vision caused by damage to the optic nerve as a result of insufficient blood supply

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2
Q

What are the two general types of anterior ischaemic optic neuropathy?

A
  • Arteritic AION

- Non-arteritic AION

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3
Q

What is arteritic anterior ischaemic optic neuropathy?

A

Loss of vision as a result of temporal arteritis

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4
Q

What causes non-arteritic anterior ischaemic optic neuropathy?

A

Due to non-inflammatory disease of small blood vessels

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5
Q

What do these cards mostly relate to?

A

Non-arteritic anterior ischaemic optic neuropathy

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6
Q

Where are the cards on arteritic anterior ischaemic optic neuropathy?

A

In temporal arteritis

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7
Q

What is non-arteritic anterior ischaemic optic neuropathy?

A

An isolated white-matter stroke of the optic nerve

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8
Q

What are the risk factors for non-arteritic anterior ischaemic optic neuropathy?

A
  • Predisposition due to type of optic disc
  • Cardiovascular risks
  • Nocturnal arterial hypotension
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9
Q

What type of optic disc predisposes to non-arteritic anterior ischaemic optic neuropathy?

A

‘Crowded’ optic disc

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10
Q

What is the optic disc?

A

The place where the axons from the retinal ganglion cells collect into the optic nerve

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11
Q

What must optic nerve penetrate?

A

The wall of the eye

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12
Q

How large is the hole in the eye for optic nerve?

A

Usually 20-30% larger than the nerve diameter

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13
Q

What is a crowded optic disc?

A

Where the optic nerve is nearly as large as the opening in the back of the eye

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14
Q

What are the cardiovascular risk factors for non-arteritic anterior ischaemic optic neuropathy?

A
  • Diabetes
  • Hypertension
  • High cholesterol levels
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15
Q

What is nocturnal arterial hypotension?

A

When there is a marked fall in BP when falling asleep

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16
Q

When does non-arteritic anterior ischaemic optic neuropathy typically present?

A

Suddenly upon waking

17
Q

What are the features of non-arteritic anterior ischaemic optic neuropathy?

A
  • Seeing poorly in one eye

- No pain

18
Q

How is vision affected in non-arteritic anterior ischaemic optic neuropathy?

A
  • Vision in affected eye is obscured by a dark shadow
  • Often just the upper or lower half of vision
  • Usually closer to the nose
19
Q

What happens to 40% of people with non-arteritic anterior ischaemic optic neuropathy after 6 months?

A

Their vision will have improved by 3 lines of a Snellen chart

20
Q

What will have happened to 10% of people with non-arteritic anterior ischaemic optic neuropathy after 6 months?

A

Their vision will have worsened by 3 lines of a Snellen chart

21
Q

What % of patients with non-arteritic anterior ischaemic optic neuropathy have opposite eye involvement within 5 years?

A

15-20%

22
Q

Is involvement of the opposite eye in non-arteritic anterior ischaemic optic neuropathy devastating?

A

Not always as impairment can be mild-moderate

23
Q

What do patients with non-arteritic anterior ischaemic optic neuropathy often have on examination?

A

Some or all signs of optic neuropathy

24
Q

What are some signs of optic neuropathy?

A
  • Decreased visual acuity
  • Dyschromatopsia
  • RAPD
  • Swollen optic nerve with splinter haemorrhages
  • Visual field defect
25
Q

What is dyschromatopsia?

A

Loss of colour vision

26
Q

Which sign of optic neuropathy is very sensitive for optic nerve dysfunction?

A

Dyschromatopsia

27
Q

How is non-arteritic anterior ischaemic optic neuropathy diagnosed?

A

Clinically

28
Q

What are the main differentials for non-arteritic anterior ischaemic optic neuropathy?

A
  • Arteritic anterior ischaemic optic neuropathy

- Optic neuritis

29
Q

When should A-AION be suspected instead of NA-AION?

A

In all patients over the age of 50

30
Q

How should patients with NA-AION over 50 be evaluated?

A

Evaluate to exclude A-AION

31
Q

What are the symptoms of A-AION?

A
  • Painful jaw muscle spasms
  • Scalp tenderness
  • Unintentional weight loss
  • Fatigue
  • Myalgia
  • Loss of appetite
32
Q

What can optic neuritis be secondary to?

A

MS

33
Q

How can non-arteritic anterior ischaemic optic neuropathy be treated?

A

There is no accepted way of reversing the condition

34
Q

How can non-arteritic anterior ischaemic optic neuropathy be prevented?

A

Risk factor modification

35
Q

What may be helpful in reducing effects of non-arteritic anterior ischaemic optic neuropathy in the early stages?

A

High dose corticosteroids