Retinal Vessel Occlusion

Question 1

Describe the blood supply to the retina

Answer 1

Central retinal artery:
- Internal carotid artery → ophthalmic artery → central retinal artery
- The central retinal artery enters the eye at the optic disc → superior and inferior retinal arteries → temporal and nasal subdivisions, which each supply a quadrant of the retina
Choriocapillaries:
- Ciliary artery → choroid capillaries
- Supplies the peripheral retina
- Supplies the macula (Hence why the macula/fovea is spared in CRAO → cherry red spot)

Question 2

Aetiology of retinal arterial occlusion

Answer 2

Thrombo-embolic from atherosclerosis
Inflammatory Arteritis e.g. GCA, LSE
Carotid, cardiac or aortic embolism
Thrombophilia e.g. protein S/C deficiency, APLS

Question 3

Difference between central vs branch vs ciliretinal retinal artery occlusion

Answer 3

Central: sudden painless TOTAL loss of vision WITH RAPD
- Globally pale retina
- Cherry red macula

Branch: sudden painless PARTIAL loss of vision WITHOUT RAPD
- Focal ischaemic region

Ciliretinal: painless CENTRAL vision loss (may be retained if occurs with CRAO)

Question 4

Investigations for retinal artery occlusion

Answer 4

Fundoscopy:
- cherry red spot on a pale retina
- Focal area of ischaemia in BRAO
CVS RF history (echo, carotid dopplers, lipids)
ESR/Temporal artery biopsy
Fluorescein angiography
OCT

Question 5

Management for retinal artery occlusion

Answer 5

Treat underlying cause
Eyeball massage → carbogen therapy (inhale 5% CO2, 95% O2), haemodilution, vasodilators, decrease intraocular pressure (i.e. paracentesis of ant. chamber)
Intra-arterial thrombolysis can be considered

Question 6

Aetiology of retinal vein occlusion

Answer 6

Systemic disease (DM, HTN, CVD)
Hypercoagulable state
Glaucoma
Polycythaemia

Question 7

Difference between central and branch retinal vein occlusion

Answer 7

Central:
- Ischaemic: sudden painless TOTAL loss of vision WITH RAPD
- Non-ischaemic: subacute mild-mod loss of vision WITHOUT RAPD

Branch: asymptomatic
- Macular involvement → visual loss

Question 8

Investigations for retinal vein occlusion

Answer 8

Fundoscopy:
- Central: Torturous dilated vessels, haemorrhages, cotton wool spots, macular and papilloedema (STORMY SUNSET)
- Branch: haemorrhage confined to retinal quadrants

fluorescein angiography (ischaemic vs. non-ischaemic CRVO)
FBC, ESR, CRP, U&Es, LFTs, lipids, clotting screen

Question 9

Management for retinal vein occlusion

Answer 9

Majority managed conservatively
ischaemic CRVO  pan-retinal photocoagulation, intravitreal anti-vascular endothelial growth factor (VEGF) agents