The retina is the "photographic film" at the back of the eye, made up of thin layers of tissue, which relay the images you see to the brain. Oxygen and nutrient-rich blood are pumped all over the body by veins and arteries. The nerve cells, like all organs in the body, need a constant supply of blood. Retinal vein occlusion occurs when a vein in the retina becomes blocked (either partial or completely). When this happens, the vision is affected.

The following symptoms may be a sign of retinal vein occlusion or other eye problems:

• Vision that is blurred
• An area in the eye where vision is missing

WHAT CAUSES RETINAL VEIN OCCLUSION?

In the retina, arteries and veins cross over and can overlap one another. In some cases an artery can harden due to atherosclerosis and press onto a vein, narrowing it. This causes clotting of the blood, which may block the blood flow in the vein, causing a retinal vein occlusion. Those with diabetes, high blood pressure, and other conditions that affect the blood vessels are more likely to develop this condition. If left untreated, retinal vein occlusions may cause vision loss.

HOW IS IT DIAGNOSED?

Your ophthalmologist will be able to diagnose and evaluate the extent of damage caused by a retinal vein occlusion. He may perform an optical coherence tomography (retinal scan) to determine the presence of swelling in the retina. An ophthalmoscope may be used to examine the complications caused by the retinal vein occlusion while fluorescein angiography may assist in assessing the extent of retinal ischaemia using a special dye injected into the bloodstream.

HOW IS A RETINAL VEIN OCCLUSION TREATED?

While there is no way to unblock retinal veins, your ophthalmologist may assist in the treatment of the symptoms and complications thereof. Treatments such as intravitreal injection of anti-vascular endothelial growth factor (VEGF) may be used to assist in suppressing the growth of abnormal new vessels while intravitreal injection of corticosteroid drugs may decrease the inflammation caused. Focal laser therapy can be done to address the ischaemia of the retina.