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Ophthalmology > Retinal Arterial Occlusion > Flashcards

Retinal Arterial Occlusion Flashcards

1
Q

What is central retinal artery occlusion?

A

A disease of the eye where the flow of blood through the central retinal artery is occluded

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2
Q

How important is retinal artery occlusion?

A

Its an ophthalmic emergency

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3
Q

What retinal artery occlusion be divided into?

A
  • Central retinal artery occlusion

- Branch retinal artery occlusion

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4
Q

What is central retinal artery occlusion?

A

When the CRA occludes before any of its branches

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5
Q

What is branch retinal artery occlusion?

A

Where one or more of the branches of the CRA are blocked

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6
Q

What are the two sources of blood supply to the retina?

A
  • Central retinal artery

- Ciliary artery

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7
Q

Where does the central retinal artery come from?

A

It is the first branch of the ophthalmic artery

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8
Q

Where does the ophthalmic artery come from?

A

It is the first branch of the internal carotid artery

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9
Q

What part of the retina is first supplied by the central retinal artery?

A

Surface of the optic disc

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10
Q

After supplying the optic disc, what happens to the central retinal artery?

A

It divides into a superior and inferior branch and then temporal and nasal branches

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11
Q

What do the superior and inferior nasal and temporal branches of the central retinal artery supply?

A

The 4 quadrants of the retina

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12
Q

What part of the retina does the ciliary artery supply?

A

The outer retina

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13
Q

How does the ciliary artery supply the retina?

A

Via the choriocapillaries of the chorid

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14
Q

What anatomical variation is relevant to retinal artery occlusion?

A

The cilioretinal artery

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15
Q

What percentage of the population are thought to have a cilioretinal artery?

A

15-30%

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16
Q

What does the cilioretinal artery do?

A

Supplies the macular retina to varying degrees

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17
Q

What is the importance of the cilioretinal artery to retinal artery occlusion?

A

It may preserve some central vision in CRA occlusion

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18
Q

How does the cilioretinal artery appear on fundoscopy?

A

A single vessel emerging from the edge of the optic disc towards macula

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19
Q

What variation does variation in location of occlusion create in retinal artery occlusion?

A
  • Different layers

- Different quadrants

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20
Q

Where in the central retinal artery will an occlusion have the most devastating effect?

A

More proximal

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21
Q

Why does a more proximal retinal artery occlusion cause a more devastating effect?

A

It will affect more layers and more areas of the retina

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22
Q

What will occlusion of a distal end branch of the retinal artery affect?

A

The inner neural layer of the part of the retina supplied

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23
Q

What will a distal retinal end artery occlusion spare?

A

The photoreceptors (so limits visual loss)

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24
Q

What is central retinal artery occlusion the ocular equivalent of?

A

Cerebral stroke - it is a process of end organ ischaemia

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25
Q

What is the most common cause of central retinal artery occlusion?

A

Atherosclerosis

26
Q

What percentage of central retinal artery occlusion cases are caused by atheroma-related thrombus?

A

80%

27
Q

What are some other causes of central retinal artery occlusion?

A
  • Embolism
  • Inflammatory disorders
  • Thrombophilic disorders
  • Infections
  • Pharmacological causes
  • Ophthalmic causes
28
Q

Where can an embolus originate to cause central retinal artery occlusion?

A
  • Carotid

- Cardiac

29
Q

What can cause a carotid embolus?

A
  • Cholesterol
  • Fibrinoplatelet
  • Calcific embolus
30
Q

What can cause a cardiac embolus?

A
  • Calcific
  • Vegetations from cardiac valve endocarditis
  • Mural thrombus e.g. AF
31
Q

What inflammatory disorders can cause retinal artery occlusion?

A
  • Giant cell arteritis
  • Polyarteritis nodosa
  • SLE
  • Pancreatitis
32
Q

What thrombophilic disorders can cause retinal artery occlusion?

A
  • Antiphospholipid syndrome
  • Protein S or C deficiency
  • Leukaemias or lymphomas
33
Q

What infections can cause retinal artery occlusion?

A
  • Toxoplasmosis

- Syphilis

34
Q

What are the possible pharmacological causes of retinal artery occlusion?

A
  • OCP

- Cocaine

35
Q

What are the ophthalmic causes of retinal artery occlusion?

A
  • Severely raised IOP
  • Trauma
  • Optic nerve drusen
36
Q

What are the risk factors for retinal artery occlusion?

A

Same as for atherosclerosis

37
Q

What is the usual presenting symptom in central retinal artery occlusion?

A

Sudden (over a few seconds) unilateral painless visual loss

38
Q

What is vision limited to in the affected eye in 94% of patients with central retinal artery occlusion?

A

Counting fingers

39
Q

What percentage of patients with central retinal artery occlusion have bilateral visual loss?

A

1-2%

40
Q

What will be seen on examination in retinal artery occlusion?

A
  • RAPD
  • Pale retina
  • Attenuation of blood vessels
  • Cherry-red macula
  • Segmentation of blood in arteries
41
Q

What should systemic examination include in suspected retinal artery occlusion?

A
  • Carotid auscultation for bruits
  • Heart sounds for murmurs
  • Radial pulse for AF
  • BP
42
Q

How is central retinal artery occlusion diagnosed?

A

Clinically

43
Q

Why may investigations be useful in suspected retinal artery occlusion?

A

To rule out underlying disease

44
Q

What investigations may be useful in identifying an underlying cause for retinal artery occlusion?

A
  • Urgent ESR and CRP in over 60
  • Coagulation studies
  • Full blood examination
  • Screening tests for vasculitis
  • Cardiovascular risk assessment
45
Q

Why should urgent ESR and CRP be performed in patients presenting with retinal artery occlusion symptoms?

A

To rule out temporal erteritis

46
Q

What are the differentials for retinal artery occlusion?

A
  • Retinal detachment
  • Vitreous haemorrhage
  • Retinal vein occlusion
  • Acute glaucoma
  • Acute optic neuritis
47
Q

Why is retinal artery occlusion an emergency?

A

The retina damage becomes rapidly irreversible

48
Q

Why is it important to recognise retinal artery occlusion in the long term?

A

To be able to treat risk factors to protect the other eye and prevent cerebro and cardiovascular incidents

49
Q

What is the main principle of retinal artery occlusion management?

A

To attempt to re-perfuse the ischaemic tissue as quickly as possible

50
Q

What is the best clinically proven treatment for retinal artery occlusion?

A

There isn’t one but a few things can be tried

51
Q

What are the options for attempting to reperfuse ischaemic tissue in retinal artery occlusion?

A
  • Firm ocular massage
  • Lowering IOP with anterior chamber paracentesis and treatment with acetazolamide
  • Dilation of the artery e.g. with sublingual isosorbide dinitrate
  • Intra-arterial fibrinolysis through local injection of urokinase into the proximal part of the ophthalmic artery
52
Q

When can firm ocular massage be used to treat retinal artery occlusion?

A

90-100 minutes of onset of symptoms

53
Q

What is a firm ocular massage?

A

Repeatedly massaging the globe over the closed lid for 10 seconds with 5 second interludes in attempt to dislodge obstruction

54
Q

What is anterior chamber paracentesis?

A

Withdrawal of a little fluid from the anterior chamber under local anaesthetic

55
Q

What is retinal artery occlusion a marker for?

A

Increased risk of ischaemic end-organ damage e.g. stroke

56
Q

What are the aims of long-term management following retinal artery occlusion?

A
  • Identify and treat underlying causes
  • Assess for coagulopathy
  • Reduce risk factors for atherosclerosis
57
Q

What underlying causes of retinal artery occlusion can be treated in the long-term?

A
  • Investigate and treat hypertension

- Carotid endarterectomy for carotid occlusion

58
Q

What risk factors for atherosclerosis can be managed to reduce the risk of further ischaemic events following retinal artery occlusion?

A
  • Hypertension

- Prophylaxis with statins and low-dose aspirin

59
Q

What will patients who have been treated for acute retinal artery occlusion require?

A

Follow-up in the eye clinic to check for complications

60
Q

What is the main complications of retinal artery occlusion?

A

Iris neovascularisation

61
Q

What can iris neovascularisation lead to?

A

Glaucoma or vitreous haemorrhage

62
Q

What are some other potential complications of retinal artery occlusion?

A
  • Retinal neovascularisation
  • Rubeosis iridis
  • Cells and flare
  • Iris necrosis
  • Cataract

Ophthalmology (16 decks)

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