Central Retinal Vein Occlusion

Question 1

What is CRVO? and how does it occur?

Answer 1

CRVO = the occlusion of the central retinal veins at the level of the lamiina cribosa or just behind.

Cause = Thrombosis (blood clot)

Question 2

What is the pathogenesis of CRVO?

Answer 2

1. Occlusion of the central retinal vein - therefore oxygenated blood can’t get to the eye = hypoxia
2. Hypoxia causes blood vessels to get damaged.
3. This causes leakage = haemorrhages and oedema.
4. Leukocytes cause capillary occlusion = no oxygen transfer to cells, leading to retinal ischaemia.

Question 3

What are the two types of CRVO?

Answer 3

1. Non-Ischaemic (75% of cases, concern = turning into ischaemic CRVO.
2. Ischaemic (more serve, concern = could develop neovascularisation)

Question 4

What are the 3 symptoms for Non-Ischaemic CRVO?

Answer 4

1. Sudden Onset
2. Unilateral
3. Blurred Vision (6/36-6/60)

Question 5

What are the 7 signs of Non-Ischaemic CRVO?

Answer 5

1. Tortuous dilated retinal veins in all 4 quadrants.
2. Round/Blot/Flame Haemorrhages
3. Occasional CWS
4. Mild/Mod Macula Oedema
5. Mild/Mod Disc Oedema
6. Mild/Absent RAPD
7. Acute signs resolve over 6-12 months

Question 6

What are the 3 symptoms for Ischaemic CRVO?

Answer 6

1. Sudden Onset
2. Unilateral
3. Severe Vision Loss (6/60 - CF)

Question 7

What are 7 main signs of Ischaemic CRVO?

Answer 7

1. Tortuous and engorgement of retinal veins in all 4 quadrants.
2. Extensive deep haemorrhages
3. Multiple CWS
4. Extensive Oedema
5. Optic Disc Oedema
6. Marked RAPD
7. Acute signs resolve over 9-12 months

Question 8

What are the 3 referral options for CRVO?

Answer 8

• If IOP normal + non-ischaemic = ROUTINE
• If elevetated IOP (up to 40mmHg) + Ischaemic = URGENT
• If IOP > 40mmHg + Ischaemic = EMERGENCY

Question 9

What is the management and investigations done for CRVO?

Answer 9

GP = manage BP, cholesterol, thyroid function + any other systemic disease

Opthalmologist:

• OCT + FFA
• For non ischaemic - follow up every 3-6 months every 2-3 yrs.
• For ischaemic - follow up monthly for 6 months.

(If macula Oedema present -> Intravitreal Anti VEGF agents)
(If neovascularisation -> Laser PRP)

If FFA shows 10DD of capillary non prefusion = ischaemic