What Are Retinal Vein Occlusions? Causes, Symptoms, and Treatment

A retinal vein occlusion occurs when blood flow out of the retina is blocked, leading to swelling and vision changes.

Branch and Central Retinal Vein Occlusion (BRVO & CRVO)

Pathophysiology

Blood being pumped into the eye by the arteries must leave the eye, and the resultant high

blood pressure in the system ruptures the small capillaries connecting the arteries and

veins. Bleeding occurs in the retina, and the capillaries may be so damaged that they

become leaky, allowing serum to leak into the retina. The retina is normally like a dry

sponge of neurological tissue, and this leakage causes it to swell or thicken like a wet

sponge, preventing the retina from functioning correctly. When the retina, particularly the

macula (center of vision), is thickened from leaking fluid, this condition is called macular

edema. Further, the damage to the retina can be so severe that it dies from lack of oxygen, a

condition known as ischemia.

Complications of BRVO and CRVO

The complications of a Branch Retinal Vein Occlusion (BRVO) or a Central Retinal Vein

Occlusion (CRVO) are consistent with the damage inflicted on the eye. The most common

cause of decreased vision is leakage, resulting in macular edema. In many patients, this

condition resolves on its own over time. However, if it persists for three months or more,

laser or surgical therapy may be necessary. Another complication is the development of

new blood vessels. These vessels do not grow into the damaged retina where they are

needed, but rather into the vitreous cavity. Such vessels can bleed and partially or

completely fill the vitreous cavity, obstructing vision. Laser treatment or vitrectomy surgery

may be required, although in some cases, waiting and adjusting head positioning may help

restore vision. A particularly severe complication, especially in CRVO cases, is the

development of new vessels on the surface of the iris, known as rubeosis. These vessels can

obstruct the eye’s outflow channels (trabecular meshwork), leading to a difficult-to-control

form of glaucoma called neovascular glaucoma. Patients are closely monitored for the first

six months following a CRVO to detect this issue early.

Treatment and Clinical Studies

The Branch Vein Occlusion Study and the Central Vein Occlusion Study were conducted to

determine the effectiveness and timing of laser photocoagulation for treating macular

edema and neovascularization. The studies concluded that laser treatment was beneficial

for macular edema in BRVO cases but not in CRVO cases. Laser therapy was also found

effective for specific indications involving neovascularization of the retina and iris in both

diseases. Laser treatment presumably works by sealing leaking vessels and reducing oxygen

demand in damaged areas, thereby decreasing the stimulus for new vessel formation.

However, it does not reopen damaged vessels or restore normal blood flow to the retina.

Recent advancements include the use of anti-VEGF medications such as Avastin, Lucentis,

and Eylea, as well as long-acting intraocular steroids like Ozurdex, which have shown

promise in managing these conditions.

Disclaimer

The information contained in this document is for informational purposes only. Diagnosis

and therapy should be based on a thorough examination by and recommendations of a qualified eye care provider

Symptoms

• Sudden blurred vision in one eye

• Distorted or dark areas in vision

Causes and Risk Factors

• High blood pressure

• Diabetes

• High cholesterol

• Glaucoma

Diagnosis and When to See a Doctor

A comprehensive exam and imaging help identify the type and severity of occlusion.

Treatment and Management

Treatment may involve medication, injections, or referral to a retinal specialist.

Summary and Next Steps

Sudden vision changes should be evaluated promptly to protect vision.