Eyes & Vision

Central Retinal Vein Occlusion (CRVO)

Central retinal vein occlusion causes sudden or subacute painless unilateral visual loss with widespread retinal haemorrhages and macular oedema; distinguish non-ischaemic from ischaemic disease because ischaemia carries a high risk of iris/angle neovascularisation and neovascular glaucoma.

In a nutshell

CRVO causes sudden or subacute painless unilateral visual loss with a blood-and-thunder fundus: four-quadrant haemorrhages, dilated tortuous veins, disc oedema and macular oedema. Distinguish non-ischaemic from ischaemic disease because ischaemia predicts neovascularisation and neovascular glaucoma. Medical-retina treatment targets macular oedema with intravitreal anti-VEGF or dexamethasone implant; established new vessels need pan-retinal photocoagulation and urgent pressure assessment.

Classic presentation

An older patient with hypertension or diabetes develops painless visual blur in one eye; fundoscopy shows widespread haemorrhages in all four quadrants, dilated tortuous veins, disc swelling and macular oedema.

Key points

CRVO affects the whole retinal venous drainage, producing a four-quadrant blood-and-thunder fundus.
Macular oedema is the major cause of central visual loss and is assessed/monitored with OCT.
Poor acuity, a relative afferent pupillary defect and extensive non-perfusion suggest ischaemic CRVO and high neovascular risk.
Anti-VEGF or dexamethasone implant may treat visual impairment from macular oedema under the medical-retina service.
New iris/angle vessels, pain or raised intraocular pressure indicate neovascular glaucoma; established neovascularisation needs urgent PRP-led treatment.
Control vascular risk and provide prolonged monitoring because non-ischaemic CRVO may convert and oedema may recur.

First-line investigation

Visual acuity, dilated fundoscopy, slit-lamp/gonioscopy and intraocular pressure, followed by macular OCT and specialist perfusion assessment where needed.

Management

Identify neovascular glaucoma

Painful red eye, halos, iris/angle new vessels or raised intraocular pressure needs same-day ophthalmic assessment for neovascular glaucoma.^2,3

Classify CRVO and quantify oedema

Use acuity, RAPD, fundoscopy, intraocular pressure, OCT and specialist perfusion assessment to distinguish non-ischaemic from ischaemic disease and identify macular oedema.^2,1

Treat macular oedema through the medical-retina service

Offer intravitreal anti-VEGF when visual impairment is caused by macular oedema; dexamethasone implant is a NICE-recommended alternative for CRVO, with IOP/cataract risks monitored.^1,4,5,2

Treat established neovascularisation

New vessels on the iris, angle, disc or retina need urgent ophthalmic treatment, usually PRP-led, with adjunctive anti-VEGF in selected cases; do not rely on macular injections alone to control neovascular risk.^2,3

Monitor and reduce vascular risk

Maintain close ischaemia/neovascular surveillance, monitor OCT and injection response, optimise blood pressure/diabetes/lipids/smoking and provide visual rehabilitation and driving support.^2,3

Exam traps

CRVO causes widespread four-quadrant haemorrhage; branch RVO is sectoral and respects the horizontal midline.
A cherry-red spot with a pale retina suggests CRAO, not CRVO.
A relative afferent pupillary defect and very poor acuity suggest ischaemic CRVO, not simply severe macular oedema.
Do not wait for pain before suspecting neovascular disease: iris/angle new vessels can precede painful neovascular glaucoma.
Anti-VEGF treats macular oedema; PRP treats established neovascularisation. They are not interchangeable treatments.

Illustrations

Central retinal vein occlusion on fundus and angiographyA two-panel retinal study showing widespread four-quadrant retinal haemorrhages and dilated tortuous veins on colour fundus photography, alongside specialist angiographic assessment. Label it as an illustrative image, not a substitute for clinical examination.Werner JU, Böhm F, Lang GE, Dreyhaupt J, Lang GK, Enders C, Wikimedia Commons · CC-BY-4.0

Cystoid macular oedema on OCTMacular OCT showing increased central retinal thickness with intraretinal cystoid fluid spaces, illustrating a structural cause of central vision loss in retinal vein occlusion.Imrankabirhossain, Wikimedia Commons · CC-BY-SA-4.0

Key sources

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.