Central Retinal Artery Occlusion Flashcards

1
Q

What is central retinal artery occlusion (CRAO)?

A

The obstruction of blood flow through the central retinal artery (rare form of ocular stroke).

It is an ophthalmic emergency.

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2
Q

What is the most common cause of CRAO?

A

Carotid artery atherosclerosis (80%)

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3
Q

What is the centrla retinal artery a branch of?

A

The ophthalmic artery (which is a branch of the internal carotid artery).

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4
Q

Causes of CRAO?

A

1) Carotid artery atherosclerosis (80%) - risk factors for CVD

2) Cardiac emboli

3) Small artery disease

4) Inflammatory disease e.g. GCA, SLE, sarcoidosis

5) Haematological disease e.g. sickle cell, APS, Factor 5 Leiden, protein S and protein C deficiency

6) Infection

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5
Q

What is the most common cause of CRAO in patients <40?

A

Cardiac emboli

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6
Q

Who is at risk of cardiac emboli causing CRAO?

A

Those with cardiac disease predisposing to embolisms such as AF, valvular disease, infection endocarditis and congenital heart disease.

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7
Q

What is normally the cause of CRAO in older diabetic or hypertensive patients with a normal carotid doppler?

A

Small artery disease i.e. local atheroma within the central retinal artery itself

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8
Q

Clinical features of CRAO?

A

Vision loss which is:

  • SUDDEN onset (seconds)
  • monocular
  • painLESS
  • severely reduced visual acuity (usually reduced to hand movements)
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9
Q

What may vision loss in CRAO be desscribed as?

A

May be described as like a ‘curtain coming down’ over vision

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10
Q

In 10% of patients, what may CRAO be preceded by?

A

Episodes of amaurosis fugax –> episodes of transient monocular visual loss

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11
Q

Examination findings in CRAO?

A

1) RAPD

2) Fundoscopy reveals a ‘cherry red’ spot at centre of macula

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12
Q

It is important to perform a systemic examination to look for possible causes in CRAO.

What exams should you do?

A

1) Carotid auscultation –> may reveal bruits indicative of turbulent flow and possible atherosclerotic disease

2) Auscultation of heart sounds –> may reveal a murmur which could indicate a possible cardiac embolism

3) Palpation of radial pulse –> may indicate AF, which is a risk factor for cardiac emboli

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13
Q

How is CRAO usually diagnosed?

A

Usually a clinical diagnosis, and investigation is typically aimed at determining the underlying cause.

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14
Q

What happens in a RAPD?

A

The pupil in the affected eye constricts more when light is shone in the OTHER eye (than when it is shone in the affected eye).

The input is not sensed by the ischaemic retina when testing the direct light reflex but is sensed during the consensual light reflex.

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15
Q

What will fundoscopy show in CRAO?

A

Pale retina with a cherry red spot.

The retina is pale due to a lack of perfusion.

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16
Q

What is the cherry red spot in CRAO?

A

The fovea, which has a thinner surface and shows the red-coloured choroid below.

17
Q

Wht are the key differentials for a sudden painless vision loss? (5)

A

1) Retinal detachment

2) CRAO

3) Central retinal vein occlusion

4) Vitreous haemorrhage (due to diabetic retinopathy)

5) Amaurosis fugax

18
Q

Investigations in CRAO? (to diagnose cause)

A

1) Serum CRP & ESR

2) Carotid artery duplex US/doppler

3) Echo and/or Holter monitering

4) Bloods e.g. coag, FBC, vasculitis screen, lipid profile, fasting blood sugars

19
Q

Purpose of testing serum ESR & CRP in CRAO?

A

Raised in patients with GCA, and should be performed urgently in all patients aged over 50 with suspected CRAO.

Although GCA is a rare cause of CRAO, visual loss is reversible with rapid administration of IV corticosteroids.

20
Q

Role of doing a carotid artery duplex US/doppler in CRAO?

A

As carotid atherosclerosis is the most common cause of CRAO this test is ordered urgently to look for underlying carotid artery atherosclerosis.

21
Q

Role of echo and/or Holter monitoring in CRAO?

A

Looking for a possible cause of cardiogenic embolism

22
Q

Difference in vision loss in CRAO vs retinal detachment?

A

In retinal detachment:

  • visual loss is progressive, starting at the peripheries of the visual field and working its way in
  • unilateral floaters and flashes may precede visual loss
23
Q

fundoscopy in CRVO vs CRAO?

A

CRAO - pale retina and cherry red spot

CRVO - widespread do-blot and flame haemorrhages (not ischaemia)

24
Q

Mx options in CRAO?

A

1) If GCA –> systemic steroids

2) Intra-arterial thrombolysis

3) Ocular massage

4) Anterior chamber paracentesis (removing fluid from the anterior chamber to reduce IOP)

5) Sublingual isosorbide dinitrate (to dilate the artery)

6) Oral pentoxifylline (to dilate the artery)

7) IV acetazolamide or mannitol (to reduce the IOP)

8) Topical timolol (to reduce IOP)

25
Q

Long term mx of CRAO?

A

Long-term management involves treating reversible risk factors and secondary prevention of CVD

26
Q
A