Central Retinal Vein Occlusion (CRVO)

What is CRVO?

Central retinal vein occlusion (CRVO) is a condition affecting the eye, specifically the retina, which is the light-sensitive tissue located at the back of the eye. This condition occurs when a blood clot obstructs the primary vein responsible for draining blood from the retina. Typically, it impacts only one eye.

While some individuals may not experience any noticeable symptoms, many with CRVO report having blurred vision. The positive aspect is that seeking treatment promptly can significantly reduce the risk of vision impairment.

What are the types of CRVO?

CRVO can be categorized into two distinct types:

  • Non-ischemic — a less severe form of CRVO that leads to leakage from the blood vessels in the retina.

  • Ischemic — a more serious form of CRVO that diminishes or completely obstructs blood flow to the retinal blood vessels.

The majority of individuals diagnosed with this condition experience the mild form of CRVO, but without appropriate treatment, it can progress to the severe type.

Additionally, there is another variant known as branch retinal vein occlusion (BRVO). BRVO is akin to CRVO but affects the smaller veins within the retina rather than the main vein.

What are the symptoms of CRVO?

A common symptom among those with CRVO is blurred vision.

If you have a very mild case of CRVO, you might not exhibit any symptoms. However, in cases of more severe CRVO, you may experience discomfort or redness in your eye. It is crucial to consult an eye care professional as soon as you notice any of these symptoms, even if they seem minor. Early intervention can significantly reduce the risk of vision loss associated with CRVO.

Am I at risk for CRVO?

Individuals aged 50 and above are at a higher risk of developing CRVO. Additionally, certain health conditions may increase your likelihood of experiencing CRVO, including:

  • High blood pressure

  • Diabetes

  • Glaucoma

  • Arteriosclerosis (the hardening of the arteries)

CRVO and glaucoma

While the precise causes of CRVO and glaucoma remain unclear, it is known that there is a connection between the two conditions.

What causes CRVO?

The exact causes of CRVO are not well understood. However, it is known that individuals may develop CRVO due to the presence of a blood clot or diminished blood flow from the central retinal vein, which is the primary vein responsible for draining blood from the retina.

When the retina does not receive adequate blood flow, it also lacks sufficient oxygen. This deficiency triggers the release of a protein known as vascular endothelial growth factor (VEGF). An excess of VEGF can lead to swelling in the retina, a condition referred to as macular edema.

How will my doctor check for CRVO?

Eye care professionals can diagnose CRVO during a comprehensive dilated eye examination. This examination is straightforward and painless; your doctor will administer eye drops to dilate (enlarge) your pupils and then examine your eyes for signs of CRVO and other potential eye issues.

Additional tests for CRVO may include:

  • Fluorescein angiogram. In this procedure, your eye doctor will inject a special dye into your arm. This dye will travel from your arm to your eye, allowing the doctor to capture images of the retinal veins as the dye circulates through them.

  • Optical coherence tomography (OCT). This test involves your eye doctor using a specialized machine to take images of your retina. This can help assess the extent of any swelling. Your eye doctor may also utilize this test post-treatment for CRVO to evaluate its effectiveness.

What’s the treatment for CRVO?

While there is no definitive cure for CRVO, various treatments can enhance your vision or prevent your symptoms from worsening. Identifying CRVO early and receiving timely treatment can help minimize the risk of vision loss. Treatment options include:

  • Injections. Medications known as anti-VEGF drugs can lower VEGF levels in your eye, which helps to reduce and prevent macular edema. Some patients may require only one injection, but it is common for multiple injections to be necessary. Steroid medications can also assist in alleviating swelling.

  • Laser treatment. If your CRVO is severe, your eye doctor may recommend a laser treatment called panretinal photocoagulation (PRP). This procedure creates tiny burns in the retina, which helps to decrease the likelihood of bleeding and the development of elevated pressure within the eye.