Central Retinal Vein Occlusion

Synonyms: CRVO

This condition has 2 broad categories, which may overlap:

• The milder form of the disease is non-ischaemic CRVO. This may resolve fully with good visual outcome, or progress to the ischaemic type.
• The severe form of the disease is ischaemic CRVO. Patients are often left with with neovascular glaucoma and a painful blind eye.

This is a common condition with an incidence of approx. 2 per 1000 in those >40 years, and 5.4 cases per 1000 aged >64 years.^1,2

Risk Factors

• Hypertension³
• Diabetes
• Smoking
• Hyperlipidaemia
• Hyperviscosity
• Glaucoma
• Clotting tendency e.g. Lupus anticoagulant, anticardiolipin antibodies, Protein C, Protein S
• Vasculitis eg. sarcoidosis, Behçet's syndrome

Symptoms

• Patient frequently presents with loss of vision or blurred vision, often starting on waking.
• Patient usually over fifty.
• Non-ischaemic CRVO may present with good vision, only few retinal haemorrhages and cotton-wool spots.
• Ischaemic CRVO presents with severe visual loss, extensive retinal haemorrhages and cotton-wool spots.

Signs

• Non-ischaemic CRVO may have no relative afferent pupillary defect, and good perfusion to the retina.
• Ischaemic CRVO shows a relative afferent pupillary defect and poor perfusion to retina.
• Haemorrhages scattered throughout fundus in typical blood-storm pattern with cotton-wool spots
• Sparse scattered haemorrhages with less complete blockage

These should help identify systemic problems.

• BP
• Blood glucose and lipids
• FBC, ESR, VDRL
• In younger patients; plasma protein electrophoresis, viscosity, thrombophilia screen including antiphospholipid antibodies and lupus anticoagulant.
• In hospital setting measure ocular pressure to exclude glaucoma.
• Fluorescein angiography is the investigation of choice. It evaluates retinal capillary non-perfusion, neovascularisation and macular oedema.
• Optical coherence tomography (OCT) scan. This is noninvasive, transpupillary imaging. It measures the retina and can detect macular oedema that fluorescein angiography has missed because of blockage from haemorrhage.⁴

• Refer immediately to on-call ophthalmologist
• Treat underlying condition if found
• Exclude glaucoma

These patients need long term follow-up to assess ongoing neovascularisation.

Drugs

As yet there is no known effective medical treatment available.^5,6 It is important to identify and treat medical problems.
The following treatments have been tried, but lack evidence for efficacy:

• Aspirin
• Thrombolytic treatment has been used with recombinant tissue plasminogen activator (rtPA) and intravenous heparinisation or haemodilution therapy.⁷
• Plasmapheresis
• Systemic anticoagulation with warfarin, heparin, and alteplase
• Systemic corticosteroids
• Local anticoagulation with intravitreal injection of alteplase
• Intravitreal injection of triamcinolone⁸

Surgical

Panretinal photocoagulation (PRP) with a laser is the usual treatment of an ischaemic retina.^5,9 This prevents new vessel formation.

• Retinal neovascularization (and secondary glaucoma or vitreous haemorrhage).
• Macular oedema ± lamellar or full-thickness macular hole.
• Permanent macular degeneration or "cellophane maculopathy".
• Optic atrophy

• Most have persisting reduced central vision due to long-term macular oedema. Occasionally, vision may improve without treatment.
• Non-ischaemic CRVO: complete recovery in 10%. Most have persistent visual impairment (50% have 6/60 vision or worse) - and a third develop ischaemic CRVO.¹⁰
• Ischaemic CRVO: >90% will have impaired vision of 6/60 or worse, 60% develop neovascularisation. 10% develop further occlusions in the same or other eye within 2 years.

There is no risk of increased long-term mortality ( c/w retinal artery occlusion).