Retinal Vein Occlusion

Central retinal vein occlusion occurs when a blood clot (thrombus) forms in the retinal veins and blocks the drainage of blood from the retina. The central retinal vein runs through the optic nerve and is responsible for draining blood from the retina.

There are four branched veins that come together to form the central retinal vein. Blockage of one of the branch veins causes problems in the area drained by that branch whereas blockage in the central vein causes problems with the whole retina.

Blockage of a retinal vein causes pooling of blood in the retina. This results in leakage of fluid and blood causing macular oedema and retinal haemorrhages. This results in damage to the tissue in the retina and loss of vision. It also leads to the release of VEGF, which stimulates the development of new blood vessels (neovascularisation).


Blockage of one of these retinal veins causes sudden painless loss of vision.


Risk Factors

  • Hypertension
  • High cholesterol
  • Diabetes
  • Smoking
  • Glaucoma
  • Systemic inflammatory conditions such as systemic lupus erythematosus



Fundoscopy examination is diagnostic of retinal vein occlusion. It give characteristic findings:

  • Flame and blot haemorrhages
  • Optic disc oedema
  • Macula oedema


Other Tests

The Royal College of Ophthalmologists guidelines from 2015 suggest checking for possible associated conditions in patients presenting with retinal vein occlusion:

  • Full medical history
  • FBC for leukaemia
  • ESR for inflammatory disorders
  • Blood pressure for hypertension
  • Serum glucose for diabetes



Patients with suspected retinal vein occlusion should be referred immediately to an ophthalmologist for assessment and management.

Management in secondary care aims to treat macular oedema and prevent complications such as neovascularisation of the retina and iris and glaucoma. The options for this are:

  • Laser photocoagulation
  • Intravitreal steroids (e.g. a dexamethasone intravitreal implant)
  • Anti-VEGF therapies (e.g. ranibizumab, aflibercept or bevacizumab)


Last updated April 2019