Retinal vein and artery occlusion
Retinal vein and artery occlusion
D E FI N I T ION
Retinal artery occlusion (RAO): Occlusion of central or a branch retinal artery.
Retinal vein occlusion (RVO): Occlusion of central or a branch retinal vein.
AE T IOLOGY
RVO:
The most common causes are diabetes mellitus, hypertension and glaucoma.
Changes in blood constituents: " Cell adhesiveness (e.g. diabetes mellitus), hyperviscosity
syndromes (e.g. multiple myeloma, hyperlipidaemia).
Changes in vessel wall: " Intra-ocular pressure (glaucoma), hypertension causing
arteriosclerosis (veins have a common sheath with arteries in the eye and may be
compressed by them), primary inflammation (e.g. vasculitis: primary vasculitides,
Beh¸cet’s syndrome, sarcoidosis).
RAO:
Emboli from carotids arteries (fibrin–platelet or cholesterol emboli) or heart valves (calcific
emboli), thrombosis, arteritis.
E P IDEMIOLOGY Common cause of sudden painless loss of vision (RVO > RAO).
H ISTORY
Sudden painless loss of vision.
RAO may be described as a ‘descending curtain’. It may be temporary (amaurosis fugax) when
the embolus is dislodged.
EXAMINA T I ON # Visual acuity (when macula is affected), visual field loss and relative
afferent pupillary defect (RAPD) may be present in both RAO and RVO. In RAO, visual field
loss is usually a unilateral quadrantanopia.
Fundoscopy:
RVO: Flame haemorrhages, cotton wool spots, swollen optic disc (in central RVO).
RAO: Pale oedematous retina with cherry red spot on the macula, narrow truncated arteries,
emboli may be seen (white – calcium; yellow – cholesterol).
Tonometry: To measure intraocular pressure (" intraocular pressure may be the cause or
complication of central RVO).
Signs of the underlying cause: Hypertension, diabetes mellitus, temporal tenderness
(temporal arteritis).
INVE S T I G A T IONS
Exclude other causes of sudden loss of vision (vitreous haemorrhage, retinal detachment,
giant cell arteritis, ischaemic optic neuropathy).
Tests to identify the cause/risk factors:
RVO: Blood glucose, ESR, exclude hyperviscosity syndromes and vasculitides, lipid profile and
intraocular pressure.
RAO: ESR, carotid doppler ultrasonography, ECG, echocardiogram, lipids.
Fluorescein angiography: Sequential photographs of the fundus are taken following IV
injection of fluorescein to identify areas of leakage and poor perfusion to assess risk of
rubeosis.
MANAGEMENT
RVO: Treat the underlying condition. Laser may be used to # macular oedema, treat ischaemic
areas and prevent neovascularization.
RAO: CO2 rebreathing (may cause arterial dilatation), IV acetazolamide, anterior chamber
paracentesis.
COM P L IC A T I ONS
Loss of vision.
Retinal vein and artery occlusion (continued)
RVO: Macular oedema, neovascularization of the retina and iris (rubeosis) and glaucoma.
RAO: Neovascularization and glaucoma can occur, although uncommon.
P ROGNOS I S
RVO: Cotton wool spots and RAPD (indicators of ischaemic retinal damage) are markers of
poor prognosis.
RAO: Very poor prognosis even with immediate treatment.
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