Retinal vein occlusion happens when a blood clot blocks a vein and obstructs the blood flow within the retina.
There are two types of RVO:
The exact cause is unknown, but RVO is more likely to occur in people with conditions that affect the blood vessels or blood flow as:
The most common symptom of retinal vein occlusion (RVO) is vision loss or blurry vision which may occur in part or all of one eye.
It can happen suddenly or become worse over several hours or days. Sometimes, in severe cases you may lose all vision suddenly.
The common causes of vision loss from RVO are:
Macular Edema
When a retinal vein is blocked, this will disrupt the blood flow within the retina. This may lead to fluid leak and swelling of the retina, called macular oedema, which causes blurring and/or loss of vision. Macular oedema is the most common cause of vision loss from RVO. Macular oedema can be treated by an eye injection of a material that helps to reduce fluid leak and retinal swelling.
Macular Ischaemia
Unfortunately, some people may develop serious damage to the blood flow at the back of the eye (macular ischemia) after vein occlusion, which can result in a permanent loss of vision.
Retinal Neovascularization
Retinal vein occlusion can cause the retina to develop new abnormal blood vessels, called neovascularization. These new vessels are very fragile and can bleed inside the eye, causing further problems.
Neovascular glaucoma
The abnormal blood vessels can grow in different parts of the eye and this may disturb the drainage of fluid from the eye, leading to a marked pressure rise in the eye called neovascular glaucoma.
The complications of RVO, especially if they are not treated, can lead to irreversible loss of vision.
Unfortunately, there is no way to unblock retinal veins. Initially, the doctor will advise treating any health problems that seem to be related to the retinal vein occlusion. The main treatment options for retinal vein occlusion are:
Eye injection or often called Intravitreal injection is a modality of treatment where a medication is injected inside the gel (vitreous) of the eye. These medications are indicated for the treatment of macular oedema secondary to retinal vein occlusion. These medications can be either:
1.Anti-VEGF injection
This is a group of medications called anti-vascular endothelial growth factor (anti-VEGF). They block the vascular endothelial growth factor (VEGF) which is a protein released from damaged blood vessels, as in retinal vein occlusion. VEGF encourages the growth of abnormal blood vessels underneath the retina, which can easily break up and leak fluid into the retina (macular oedema). Blocking the VEGF may help to treat macular oedema secondary to retinal vein occlusion.
2. Ozurdex (dexamethasone implant):
This is a special tiny implant that slowly releases steroid material when injected inside the eye. The implant contains biodegradable steroid material that gradually dissolves within the eye. The drug usually lasts for about 3-4 months. Ozurdex is used to treat macular oedema secondary to retinal vein occlusion (and other retinal conditions). The steroid material helps to reduce inflammation and retinal swelling (oedema).
This type of laser treatment aims to treat areas of retinal damage caused by retinal vein occlusion. This would help to stop the proliferation of new blood vessels and prevent further damage. The laser can be applied to part of the peripheral retina, called sector laser treatment or to the whole peripheral retina, called pan-retinal photocoagulation.
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