Central retinal vein occlusion – assessment

Description

Central retinal vein occlusion (CRVO) is a destructive condition with a dramatic ophthalmoscopic appearance: widespread hemorrhages in all quadrants of the retina. It is usually attributed to a thrombus in the central retinal vein, at the level of the lamina cribrosa within the optic disc. The vein at the arteriovenous crossing is also at risk of blockage, as a stiff-walled atheromatous artery may compress the lumen of the adjacent thin-walled vein, creating blood turbulence and thrombotic build-up. CRVO is frequently associated with systemic diseases, particularly hypertension, arteriosclerosis, diabetes, and hypercoagulation or vasculitic disorders. CRVO also has an association with glaucoma, as raised intraocular pressure (IOP) may compress the central retinal vein. There is a spectrum of disease in CRVO, in relation to the amount of venous obstruction, consequent stagnation of blood flow, retinal hypoxia and damage to the retinal capillary endothelial cells. The retinal capillary non-perfusion or closure (capillary ischemia) is shown as hypofluorescence on fluorescein angiography. Damage to the capillary endothelial cells causes breaches in the blood-retina barrier, leading to the clinical signs of blood leakage from the vessels.

Symptoms

The patient may report a sudden, painless, permanent loss of vision in one eye. There may be a history of previous brief loss of vision (amaurosis fugax), transient ischemic attack (TIA) or stroke (cerebrovascular accident).

Signs

The spectrum of disease in CRVO is evident clinically:

1. Ischemic CRVO has the most dramatic presentation, with dilated tortuous retinal veins, confluent dot, blot and flame hemorrhages in all four quadrants, and multiple cotton-wool patches. Visual loss is usually worse (<20/400) and there may be a relative afferent pupillary defect (RAPD). There is a significant risk within 1-3 months of neovascularization of the iris (rubeosis) or anterior chamber angle, causing neovascular glaucoma. Retinal neovascularization occurs less frequently
2. Non-ischemic CRVO is usually less florid in appearance, with acuity in the 20/20 to 20/400 range. Vision may be decreased because of macular edema or hemorrhage. Although neovascular complications are less common, due to adequate capillary perfusion, an ischemic course may subsequently develop.
3. Milder forms of non-ischemic CRVO may be termed ‘venous stasis retinopathy’ or ‘incomplete CRVO’. If the vein bifurcates posterior to the lamina cribrosa, a hemi-retinal vein occlusion may occur

There may be raised intraocular pressure due to glaucoma or ocular hypertension.

Prevalence

Although overall vascular occlusions are uncommon (1 : 1000), they are relatively common (1 : 100) in specific at-risk groups, such as people aged over 50 years.

Significance

Central retinal vein occlusion may cause legal blindness in the affected eye, and there is a slight risk of the other eye also being afflicted. It is also a warning of potentially life-threatening systemic conditions, such as stroke, that require prompt investigation and treatment.

Differential diagnosis

Branch retinal vein occlusion; branch retinal vein occlusion – sequelae; ocular ischemic syndrome (all usually unilateral); hypertensive retinopathy; diabetic retinopathy; papilledema (usually bilateral).

See also

Central retinal artery occlusion; Branched retinal artery occlusion; Neovascular glaucoma.

Management

See Central retinal vein occlusion – management.