Fundus: Retinal Vascular Occlusion

Question 0

What are six chief causes of sudden painless monocular loss of vision?

Answer 0

1. Retinal vein occlusion
2. Retinal artery occlusion
3. Anterior ischaemic optic neuropathy
4. Vitreous haemorrhage
5. Macular haemorrhage
6. Optic neuritis

Question 1

Retinal venous and arterial occlusions should always be considered in the differential diagnosis of a patient presenting with what?

Answer 1

Sudden painLESS loss of vision.

Retinal vascular occlusion is usually a manifestation of systemic disease. Consider Virchow’s triad: outside the wall, in the wall, and inside the lumen.

Both artery and vein occlusions are usually unilateral.

Question 2

Venous occlusions can affect which two veins?

Answer 2

1. Central retinal vein
2. A ‘branch’ retinal vein occlusion (a tributary of CRV). Thrombosis frequently occurs at an arteriovenous crossing point. Retinal changes are confined to the area of retina drained by the vessel.

Same principle for central retinal artery occlusion!

Central retinal vein occlusion and some branch occlusions can involve the macula, so sudden painless loss of central vision results.
There may be an RAPD.

Question 3

What 4 features can be seen on fundoscopy in retinal vein occlusion?

Answer 3

1. Flame, dot and blot haemorrhages
2. Cotton wool spots
3. A swollen optic disc
4. Macular oedema

Question 4

What are two major complications of retinal vein occlusion?

Answer 4

1. Macular oedema
2. Neovascularisation of the iris (rubeosis) and of the retina.

Rubeosis can lead to a severe, painful glaucoma which is difficult to control.

Question 5

What is the major occular association with retinal vein occlusion (ie. risk factor)?

Answer 5

Elevated IOP.

The diagnosis of retinal vein occlusion is clinical. Ix are directed primarily at excluding treatable associations (hypertension, diabetes, blood dyscrasias, vasculitis, IOP).

Question 6

Treatment is of the disease and of any systemic association. How would you treat the following in retinal vein occlusion?

1. Macular oedema
2. Neovascularisation
3. Rubeotic glaucoma

Answer 6

1. Macular oedema: Laser Rx to reduce oedema and improve vision, may be successful in retinal vein occlusion.
2. Neovascularisation: Laser of ischaemic areas (as with proliferative diabetic retinopathy). Prophylactic laser after vein occlusion but before neovascularisation is not yet proven.
3. Rubeotic glaucoma: a variety of Rx, incl. laser and surgery are used, but the outcome is usually poor. A painful blind eye may need to be removed.

Question 7

Which lead to more severe visual loss, retinal vein or artery occlusions?

Answer 7

Retinal artery occlusions.

Question 8

What is the commonest cause of arterial occlusion, compared with vein occlusion?

Answer 8

Artery occlusions is usually from embolisation, with the embolus originating most frequently from a source in the carotid artery and consisting of cholesterol, calcific plaques or fibrinoplatelet material. US of carotids may show significant stenosis.

Vein occlusion is usually a thrombosis within the lumen of the vein. Abnormalities of blood constituents may promote thrombus formation.

Inflammation within the vessel wall, arteritis, may also cause occlusion.

Question 9

In artery occlusion, compare an embolism passing through vs a stationary embolism.

Answer 9

Emboli may pass through the retinal vascular system, causing transient rather than permanent visual loss.
A stationary embolus, however, causes retinal failure beyond the point of obstruction.

Question 10

True or false: a branch retinal artery occlusion may not give symptoms if the area affected is away from the macula.

Answer 10

True.

Fun fact: unlike other ischaemic retinal diseases, neovascularisation in retinal artery occlusion is uncommon.

Question 11

When a patient has experienced similar but transient episodes of acute severe monocular loss of vision, due to central artery occlusion, what are these episodes called?

Answer 11

Amaurosis fugax.

Question 12

True or false: an RAPD is usually present in central artery occlusions but not in branch artery occlusions.

Answer 12

False.
It is true that an RAPD is usually present in central artery occlusions, but it may also frequently be present in branch artery occlusions.

Question 13

Describe some features on fundoscopy which are present in the weeks following retinal artery occlusion.

Answer 13

1. Affected retinal arterioles may be thinned, with segmentation of the columns of blood.
2. The optic disc is not usually pale or swollen (unlike ischaemic optic neuropathy).
3. Oedematous retina is devoid of usual glistening appearance and may appear whitish and opaque.
4. A cherry-red spot in the centre of the macula is usual (recedes after 6 weeks).
5. One or two cotton wool spots are a common finding.
6. Emboli may be seen within the arterioles.

Question 14

Which condition, although usually causing ischaemic optic neuropathy rather than embolic retinal artery occlusion, should still always be considered alongside a retinal artery occlusion?

Answer 14

Giant cell arteritis.

Key features are pain and tenderness along the superficial temporal artery and elevated ESR and CRP.

Question 15

Treatment of retinal artery occlusion?

Answer 15

No specific Rx which reliably restores vision, but urgent referral to confirm Dx is necessary (esp. if a dx of treatable giant cell arteritis, not to be missed).
Regular prophylactic aspirin (if not contraindicated).
Carotid endarterectomy may be indicated in severe carotid stenosis.

Question 16

What are the two key features of retinal vein occlusion?

Answer 16

1. Tortuous dilated veins

2. Flame haemorrhages localised to area drained by affected vein.

Question 17

What are five key features of retinal artery occlusion?

Answer 17

1. History of amaurosis fugax
2. Retinal pallor
3. Cherry red spot on macula
4. Narrow truncated arteries
5. Embolus