Section 3: Aetiology and risk factors
Retinal vein occlusion is due to thrombosis of retinal veins (central, hemi or branch) 1-3.
Established cardiovascular risk factors are the predominant medical associations for
both central and branch vein occlusions and are summarised below and include
differentiation by age and ethnic groups. (See table 1) 8,9
Strength of evidence
This is the predominant risk factor with up to 64% of patients having
hypertension (Table 1) in the older age group (more than 50 years).10 This is
more prevalent in BRVO than CRVO. A new diagnosis or uncontrolled
hypertension is a common finding. Inadequately controlled hypertension is
associated with recurrence of RVO in the same eye or fellow eye involvement.
Hyperlipidaemia (cholesterol > 6.5 mmol/l) is the predominant association in
the younger age group (< 50 years) of patients with retinal vein occlusion and is
associated in up to 50% of older patients.11
 Diabetes mellitus
Diabetes mellitus (table 1) is associated with retinal vein occlusion. This may
be due to an increase of other cardiovascular risk factors (e.g. 70% of type II
diabetics are hypertensive).10,12,13
Current evidence suggests an association between central retinal vein occlusion
and glaucoma.7,14 One study suggests that BRVO is associated with glaucoma 12
Factor V Leiden and other such abnormalities have been implicated in RVO but
their aetiology is unclear. Deficiency or abnormal activity of various factors
have been identified in patients with RVO including protein S,C, anti-thrombin
3, activated protein C resistance, hyperhomocysteinaemia and the presence of
lupus anticoagulant or anti-cardiolipin antibody deficiency.15 Thombophilia
and the other rarer associations e.g. oral contraceptive pill, and optic disc
vasculitis assume more importance in the younger patients (<50 years).16,17
Other Important Observations
Myeloproliferative disorders occur in 1% of patients presenting with retinal
vein occlusion.9
Other rare associations with retinal vein occlusion include:
  • Inflammatory disease that cause or are associated with retinal vasculitis – Behçets disease, polyarteritis nodosa, sarcoidoisis, Wegener’s Granulomatosis, Goodpasture’s Syndrome.

  • Chronic renal failure and other secondary causes of hypertension and diabetes e.g. acromegaly, Cushing’s syndrome.

  • Secondary causes of hypercholesterolaemia eg hypothyroidism.
Introduction Methods used Risk factors CRVO
BRVO Medical treatment Cardiovascular problems Young patient
References. Tables Main index Main page.