Ophthalmology - Central Retinal Vein Occlusion, Central Retinal Artery Occlusion

Question 1

Central Retinal Vein Occlusion (CRVO) - what is it and what does it cause?

Answer 1

Central retinal vein occlusion occurs when a blood clot (thrombus) forms in the retinal veins and blocks the drainage of blood from the retina, resulting in the vein to leak blood and excess fluid into the retina

The central retinal vein runs through the optic nerve and is responsible for draining blood from the retina

This excess fluid often collects in the area of the retina responsible for central vision called the macula. When the macula is affected, central vision may become blurry.

Question 2

CRVO - blockage of a retinal vein leads to what complications?

Answer 2

1. Blockage of a retinal vein causes pooling of blood in the retina
2. This results in leakage of fluid and blood causing macular oedema and retinal haemorrhages
3. This results in damage to the tissue in the retina and loss of vision
4. It also leads to the release of VEGF, which stimulates the development of new blood vessels (neovascularisation)

Question 3

CRVO - what is the classic sign of CRVO?

Answer 3

Blockage of one of these retinal veins causes:

Sudden PAINLESS loss of vision

Usually Unilaterally

Question 4

CRVO - risk factors?

Answer 4

• Hypertension
• High cholesterol
• Diabetes
• Smoking
• Glaucoma
• Systemic inflammatory conditions such as systemic lupus erythematosus

Question 5

CRVO - what is the main investigation done and what are the three characteristic findings?

Answer 5

Fundoscopy:

1. Flame and blot haemorrhages
2. Optic disc oedema
3. Macula oedema

Question 6

CRVO - management?

Answer 6

Management in secondary care aims to treat macular oedema and prevent complications such as neovascularisation of the retina and iris and glaucoma The options for this are:

• the majority of patients are managed conservatively
• macular oedema - intravitreal anti-vascular endothelial growth factor (VEGF) agents (e.g. ranibizumab, aflibercept or bevacizumab)
• retinal neovascularization - laser photocoagulation

Question 7

Central retinal artery occlusion (CRAO) - what is the characteristic thing it causes?

Answer 7

Causes sudden unilateral visual loss

Question 8

CRAO - what are the causes?

Answer 8

due to thromboembolism (from atherosclerosis) or arteritis (e.g. temporal arteritis)

Question 9

CRAO - what signs do you get?

Answer 9

Features include:

afferent pupillary defect

‘cherry red’ spot on a pale retina