Retinal Vein Occlusion

A retinal vein occlusion is sometimes called an “eye stroke”. It occurs when there is a blockage in one of the veins that returns blood from the retina to the heart. Blood cannot drain from the retina and leaks into the retinal tissue resulting in haemorrhage and swelling in the retina.

The lack of blood supply can result in permanent damage to the retina. Ischaemia (lack of oxygen) or neovascularisation (the growth of new blood vessels) can occur. New blood vessels are fragile and tend to bleed and can result in bleeding to the vitreous gel, retinal scarring and retinal detachment.

If these new vessels develop in the drainage angle of the eye they can result in neovascular glaucoma (a severe form of glaucoma).  The severity of vision loss depends on which vein is blocked. There are two types of retinal vein occlusion: Central retinal vein occlusion (CRVO) where the main retinal vein is blocked, and Branch retinal vain occlusion (BRVO) where a smaller branch vein is blocked.

Branch Retinal Vein Occlusion

Central Retinal Vein Occlusion

Investigations are aimed at assessing the level of vision, identifying the site and severity of the blockage, assessing areas of ischaemia and determining whether macular oedema is present.

Tests may include:

• Vision assessment.
• Retinal examination and photography.
• Optical coherence tomography (OCT) – a high definition image of the retina and its layers.
• Fluorescein angiography – a dye injected into the arm travels to the retinal vessels to be photographed and show blockages.
• You may also have blood work for diabetes, cholesterol, inflammatory conditions and blood clotting disorders.

While there is no way to actually unblock retinal veins, the subsequent eye problems that can develop following a retinal vein occlusion can be treated.

Treatment for retinal vein occlusions include:

• Injections into the eye of anti-vascular endothelial growth factor (anti-VEGF) drugs. These aim to reduce the growth factor that contributes to macular oedema.
• Injections of corticosteroid drugs into the eye to reduce the inflammatory components contributing to oedema.
• Retinal laser – focal (to reduce oedema) or pan-retinal (to reduce the stimulus for new vessels to develop) laser photocoagulation may be used.

The outlook for this condition does vary, with many people recovering and regaining most of their vision, however for some patients the vision does not return. It is important that any general health risk factors (blood pressure, cholesterol, diabetes, smoking etc) are addressed to protect the other eye as well as the blood vessels in the rest of the body.