Retinal Vein Occlusion (RVO)

The process of converting reflected light into images begins at the retina, a thin layer of tissue at the back of the eye. Here millions of photoreceptor cells translate the incoming and focused light into full-color visual information that then heads to the brain, where it's instantly interpreted and defined.

When your eyes are healthy, this intricate process operates seamlessly. Just as every part of the body requires a constant and unimpeded blood supply bringing oxygen and nutrients from the heart and carrying deoxygenated blood back to it, so do vital structures within the eye.

Why it occurs

Retinal vein occlusion (RVO) occurs when the blood flow heading back to the heart gets blocked. With no means for the blood to drain, hemorrhages (bleeding) and leakage from the blocked blood vessels can ensue. While RVO can develop due to narrow retinal veins, people with diabetes, high cholesterol, high blood pressure, and other circulation issues have a higher risk.

Two types of Retinal Vein Occlusion

A branch retinal vein occlusion (BRVO) and a central retinal vein occlusion (CRVO) describe the two main locations where retinal vein occlusion can occur.

Central vein retinal occlusion develops from a blood clot or reduced blood flow in the central retinal vein that drains the retina. Most patients with CRVO develop it in one eye, and its specific cause is still unknown.

The common risks factors for CRVO include:

• Diabetes
• High blood pressure
• Conditions that may increase the risk of blood clots

A branch retinal vein occlusion typically occurs when a branch retinal artery, affected by the hardening of the arteries, compresses a branch retinal vein.

The common risk factors for BRVO include:

• Uncontrolled high blood pressure
• Being overweight or obese (increased body mass index)
• Cardiovascular (heart) disease
• Glaucoma
• In younger patients who suffer BRVO, an abnormal tendency to develop blood clotting is also possible

Retinal vein occlusion can lead to the following developments and consequences:

• Macular edema
• Abnormal blood vessel development (neovascularization)
• Neovascular glaucoma
• Vitreous hemmorhage
• Retinal detachment
• Blindness

Symptoms and treatment

It’s essential to be aware of the signs and symptoms of RVO so that you can get prompt, appropriate care. Typically occurring in just one eye, blurring and vision loss may be initially subtle and painless but can quickly worsen.

Mild CRVO may show no symptoms. However:

• Many patients with CRVO have symptoms such as blurry or distorted vision due to swelling of the center part of the retina, known as the macular edema
• Some patients have mild symptoms that wax and wane, called transient visual obscurations
• Patients with severe CRVO and secondary complications such as glaucoma (a disease characterized by increased pressure in the eye) often have pain, redness, irritation and other problems

BRVO causes a sudden, painless loss of vision. If the affected area is not in the center of the eye, BRVO can go unnoticed with no symptoms.  

In addition to treating medical conditions that contribute to RVO, you may need specific intravitreal injections, focal laser therapy, or pan-retinal photocoagulation therapy. These methods can help address damaging edema and the development of abnormal blood vessels.

It’s important to note that early detection of macular edema or abnormal blood vessels is important; most patients can avoid severe vision loss if treatment is initiated before substantial damage develops in the eye.