The Eye's Silent Threat: A Closer Look at Retinal Vascular Occlusions

Originally published by Retina Group of Florida

While some vision conditions may have noticeable symptoms, retinal vascular occlusions (i.e., blockages of blood vessels) can be sudden and unexpected. If untreated, retinal vein occlusions (RVOs) and retinal artery occlusions (RAOs) may lead to permanent vision loss. Retinal vascular occlusions often require immediate medical attention, so it’s important to be aware of their causes, risk factors, and symptoms.

Retinal Vascular Occlusion Development and Causes

Within the eye, arteries continually deliver oxygen-rich blood to the retina, while veins remove depleted blood and any waste products. Should this cycle be disrupted, blood and fluid may leak into the retinal tissue.

RAOs often develop due to blood clots and fatty deposits, especially if your eyes’ blood vessels have hardened, although clots may form elsewhere. RAOs may also develop due to issues affecting the heart, immune response concerns, or intravenous drug abuse. RVOs are typically caused by the eye’s veins being compressed, increasing clot development. They may also occur from conditions affecting blood flow, like diabetes.

Retinal Vascular Occlusion Types Explained

Specific occlusion types may depend on whether they develop within arteries or veins, and their locations. They include:

Central Retinal Artery Occlusion (CRAO)

A CRAO, or eye stroke, is a serious health threat that develops in the retina’s central main artery. While the most common symptom is spontaneous, painless vision loss, you may have blind spots, visual distortions, and permanent loss of peripheral vision.

Branch Retinal Artery Occlusion (BRAO)

BRAOs are blockages developing in branches growing from the central retinal artery. They can stop the blood supply to the macula, the retina’s center, which enables central vision. BRAOs may have no symptoms, and patients can expect to have fair-to-good eyesight after proper treatment.

Central Retinal Vein Occlusion (CRVO)

Retinal vein occlusions (RVOs) are the second-most common retinal vascular disease, and a primary cause of vision loss among older patients, affecting over 16 million people. If the main retinal vein is targeted, this causes a central retinal vein occlusion (CRVO). They may be nonischemic, a mild form causing leaking retinal blood vessels, or ischemic, a severe type reducing or blocking blood flow.

Should CRVOs progress, you may have bleeding, fluid leakage, and structural vein damage. Neovascularization may occur, in which new, fragile veins grow underneath the retina, bleeding and leaking fluid into it. Symptoms like floaters, hazy vision, and issues with night vision and lighting changes may occur.

Branch Retinal Vein Occlusion (BRVO)

BRVOs target smaller veins branching off from the central retinal vein. You may experience no symptoms, although there could be floaters, peripheral vision loss, and central vision distortions or blurriness. You may also have bleeding in the vitreous.

Common Risk Factors for Retinal Vascular Occlusions

Typically, occlusions affect people in their 60s, with men more at risk. If blood flow’s quickly restored, retinal occlusions only last for a few seconds or minutes, with a single eye affected. Other risk factors include:

• Smoking
• Diabetes
• High cholesterol
• Being overweight or obese
• Narrowing of the carotid artery
• Glaucoma
• Cardiovascular disease
• High blood pressure
• Blood-clotting issues, specifically among younger BRVO patients.

Having unusually thick and sticky blood, especially among female CRAO patients taking birth control pills
Retinal vascular occlusions are associated with macular edema, involving fluid leaking into the retina, swelling the macula, and forming a blister. If untreated, it can result in neovascularization, irreversible macular damage, and permanent vision loss.

Your ophthalmologist will usually recommend regular monitoring and management of underlying conditions and risk factors. Occlusions, particularly BRAOs, CRAOs, and CRVOs, may be considered medical emergencies, raising your risks for a cerebral stroke and permanent vision loss.

Learn More About Retinal Vascular Occlusions

Sudden and unexpected, retinal occlusions may cause serious damage and permanent vision loss. Regular monitoring, provided by comprehensive ophthalmologic exams, is crucial and may help to preserve vision. If you’d like to schedule a consultation with a retina specialist, find a Retina Consultants of America doctor near you.