Retinal Vein Occlusions

What is a Retinal Vein Occlusion?

The retina, a thin light sensing membrane at the back of the eye, has many small blood vessels to provide it with nutrients and oxygen. If one of the veins gets blocked, this is known as a retinal vein occlusion. A blocked vein damages blood vessels and blood can leak in the eye. This can be sight threatening because your retina needs proper blood flow to detect light and send the message to your brain.

There are two different types of retinal vein occlusions:

  • Central retinal vein occlusion (CRVO) – when the main vein collecting all the blood from the eye becomes blocked
  • Branch retinal vein occlusion (BRVO) – when one of the smaller branches of vessels becomes blocked

Risk Factors

Certain illnesses that affect your blood and vessels can put you at risk for developing a vein occlusion, including:

  • Diabetes
  • Glaucoma
  • High blood pressure
  • Age-related vascular disease
  • Blood disorders

If a vein occlusion occurs in one eye, there is an increased chance that it could also occur in your other eye.


Some of the symptoms of a retinal vein occlusion include:

  • sudden loss of vision
  • distorted vision
  • usually painless
  • sometimes aymptomatic, if vein occlusion does not occur in a central location

Depending on where the vein occlusion occurs, you may or not have symptoms. It is important to seek immediate medical help if you do experience any of these symptoms, as well as keep up with regular eye exams. Your ophthalmologist can detect a retinal vein occlusion by examining the back of your eye with special lenses, or by performing a fluorescein angiogram. Fluorescein angiography is a procedure that takes photographs of how the blood flows within your eye.


When a vein becomes blocked, the blood has nowhere to go, so fluid and blood leak into the retina. This can have many serious effects:

  • Macular edema – The macula is the spot at the back of your eye that allows you to see fine detail. If blood and fluid leak underneath the macula, it swells upwards and distorts your vision.
  • Abnormal blood vessel growth (neovascularization) – retinal vein occlusions prevent the retina from receiving proper blood flow. In an attempt to make up for this, your eye may form new vessels to nourish it. However, these vessels are very fragile and leaky, causing blood to leak inside your eye and underneath the retina. This distorts your vision and can lead to more serious complications, such as a retinal detachment.
  • Neovascular Glaucoma – in severe cases of retinal vein occlusions, new vessels can grow all the way onto the iris, the colored part of your eye. Having abnormal vessels here can block the fluid from draining from your eye, leading to increased pressure. Having an increased pressure can be very painful and fluid can push against your optic nerve, damaging it and causing vision loss. This is known as glaucoma.


Although there is no known cure for a retinal vein occlusion, there are some treatment options available that may be able to prevent further complications and vision loss. These include intraocular injections or laser surgery to try and reduce the bleeding, swelling, and new vessels formation.

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