Mr Venki Sundaram
Consultant Ophthalmic Surgeon
MD FRCOphth MRCOphth BMBCh BSc

Retinal vein occlusion

A blockage can occur in the main central vein, or one of its branch veins, causing either a Central Retinal Vein Occlusion (CRVO) or a Branch Retinal Vein Occlusion (BRVO).

Retinal Vein Occlusion

Central Retinal Vein Occlusion (CRVO)

CRVO most commonly occur in patients over 50 years of age. The most common causes include diabetes, hypertension, raised cholesterol, cardiovascular atherosclerotic disease, smoking and raised eye pressure. Occasionally, rare blood disorders can be a cause of developing a CRVO and this is more common in younger patients.

Symptoms are typically a painless, sudden reduction in vision. Extensive retinal haemorrhages typically occur (see Image 1).

Complications of CRVO include a growth of abnormal, fragile new blood vessels in the retina or iris, which can bleed and cause further loss of vision or glaucoma.

Also, macular oedema (thickening and swelling of the macula – see Image 2) can occur due to damage of retinal vessels, causing leaking of fluid into the macular region and further blurring of vision and distortion.

Retinal haemorrhages

Image 1 – retinal haemorrhages and damage caused by a CRVO

Macular oedema

Image 2 – macular oedema due to a CRVO

Treatments

Once a CRVO has occurred, there is unfortunately no treatment that can reverse the blockage of the vein. However, management instead is to identify and control any underlying risk factors (mentioned above) such as diabetes, raised blood pressure/cholesterol, smoking or raised eye pressure. This can prevent the risk of a CRVO occurring in the other eye.

  • Monitoring – it is important that patients are monitored regularly for at least a period of 2 years to assess whether there is growth of abnormal blood vessels in the eye, which can further impair vision. If new blood vessels do develop, laser treatment (PRP) is normally give to prevent further complication.
  • AntiVEGF therapy – Lucentis and Eylea are approved to treat macular oedema due to CRVO. Numerous clinical trials have shown that these therapies are very effective in reducing macular oedema and improving vision. Patients typically need a course of injections.
  • Steroid therapy – Ozurdex is a steroid implant that is injected into the eye and has been approved for treating macular oedema in CRVO.

Branch Retinal Vein Occlusion (BRVO)

BRVO are three times more common that CRVO, and usually occur in an area where there is pressure from an overlying artery on a retinal vein. There are similar underlying risk factors (except for raised eye pressure) that are associated with BRVO.

Symptoms can also include loss of vision, and patients may report a loss of part of their peripheral vision (visual field defect), that corresponds with the location of the BRVO.

Similar to CRVO, abnormal blood vessels can develop in the retina which can bleed if untreated.

Also, macular oedema can develop which can significantly affect vision.

Treatments

As per CRVO, there is unfortunately no treatment that can reverse the blockage of the vein in a BRVO. However, management instead is to identify and control any underlying risk factors (mentioned above) such as diabetes, raised blood pressure/cholesterol and smoking. This can prevent the risk of a BRVO occurring in the other eye.

  • Monitoring – it is important that patients are monitored regularly for at least a period of 2 years to assess whether there is growth of abnormal blood vessels in the eye, which can further impair vision. If new blood vessels do develop, laser treatment (PRP) is normally give to prevent further complication.
  • AntiVEGF therapy – Lucentis is approved to treat macular oedema due to BRVO. Numerous clinical trials have shown that these therapies are very effective in reducing macular oedema and improving vision. Patients typically need a course of injections.
  • Macula Laser – small, light laser spots which are applied to the area of macular swelling can be effective in reducing the oedema and restoring vision
  • Steroid therapy – Ozurdex is a steroid implant that is injected into the eye and has been approved for treating macular oedema in BRVO.