Central Retinal Vein Occlusion
What Happens in CRVO
The retina is a thin layer of tissue at the back of your eye that senses light and sends signals to your brain. Arteries bring oxygen and nutrients to the retina, while veins carry used blood away. The central retinal vein is the main drainage route for blood leaving the retina.
A clot or narrowing in the central retinal vein slows or stops blood flow out of the retina. Pressure builds up, and blood and fluid leak into the surrounding tissue. This causes swelling in the macula, the part of the retina responsible for sharp central vision, and can damage the cells needed for seeing fine details.
CRVO is divided into two types based on how much blood flow is affected. Non-ischemic CRVO is milder, with partial blockage and better blood supply to the retina. Ischemic CRVO is more severe because large areas of the retina do not get enough oxygen. Ischemic CRVO has a higher risk of serious complications, including abnormal blood vessel growth. When only a smaller branch of the retinal vein is affected rather than the central vein, the condition is known as branch retinal vein occlusion.
Without treatment, CRVO can lead to problems that threaten vision.
- Macular edema: Fluid buildup in the macula causing blurry central vision
- Neovascular glaucoma: Abnormal blood vessels grow and raise pressure inside the eye
- Retinal ischemia: Lack of oxygen damages retinal tissue
- Vitreous hemorrhage: Bleeding into the gel-like fluid inside the eye
Complications such as vitreous hemorrhage can cause a sudden increase in floaters or a significant drop in vision and require prompt evaluation.
Symptoms of CRVO
Most people notice a sudden, painless drop in vision in one eye. Blurriness often affects the center of your sight, making it hard to read, recognize faces, or see fine details. Some people also see wavy or distorted lines.
You may see dark spots, strings, or cobwebs drifting across your vision. These floaters can appear when blood leaks from damaged vessels. A sudden increase in floaters needs prompt evaluation.
Retinal swelling can make colors look faded or less vivid than usual. This change may be subtle at first but can become more noticeable over time.
You may find it harder to see in dim lighting or at night. This can affect everyday tasks like driving after dark.
CRVO itself is usually painless. Pain, redness, or a feeling of pressure may develop if neovascular glaucoma forms. Any new eye pain should be checked right away.
Causes and Risk Factors
A blood clot, called a thrombus, typically forms where the central retinal vein passes through a narrow space near the optic nerve. Hardening of nearby arteries can compress the vein, slowing blood flow and making clots more likely.
CRVO is more common in people over 50. Blood vessels become stiffer with age, and conditions that affect the heart and blood vessels are more common in older adults.
Several health problems make CRVO more likely.
- High blood pressure: Damages blood vessel walls over time
- Diabetes: Causes changes to blood vessels throughout the body
- Glaucoma: Higher eye pressure may affect blood flow near the optic nerve
- High cholesterol: Leads to fatty buildup in arteries
- Blood clotting disorders: Increase the chance of clot formation
Certain habits can harm blood vessels and raise CRVO risk.
- Smoking: Injures blood vessel walls and increases clotting
- Lack of physical activity: Weakens circulation
- Obesity: Strains the heart and blood vessels
- Heavy alcohol use: Affects blood pressure and clotting
How CRVO Is Diagnosed
Your retina specialist will use drops to widen your pupil, allowing a clear view of the retina, optic nerve, and blood vessels. This exam can reveal swelling, bleeding, and signs of blocked blood flow.
Optical coherence tomography, or OCT, uses light waves to create detailed cross-section images of the retina. This test shows how much fluid has built up in the macula and helps track changes over time.
During fluorescein angiography, a special dye is injected into a vein in your arm, and a camera captures images as the dye travels through the blood vessels in your eye. This highlights areas of blockage, leaking vessels, and parts of the retina that are not getting enough blood.
High-resolution photos of the retina are taken to document the current state of your eye. These images help your retina specialist compare your condition over time.
Checking the pressure inside your eye, called tonometry, is important because CRVO can lead to neovascular glaucoma. Finding high pressure early allows for quicker treatment.
Blood tests may check for diabetes, high cholesterol, clotting disorders, and inflammatory conditions. Managing these underlying issues is part of your overall care plan.
Treatment Options
Anti-VEGF medications are injected into the eye to reduce abnormal blood vessel growth and leaking. These injections help decrease macular swelling and can improve or stabilize vision. Most patients need a series of treatments over several months, with ongoing monitoring to decide when more injections are needed.
Steroid medications reduce inflammation and swelling in the retina. They may be given as injections or as a slow-release implant placed inside the eye. Your retina specialist will monitor for side effects, including increased eye pressure and cataracts.
Laser treatment can seal leaking blood vessels and reduce the risk of abnormal vessel growth. It is most often used for ischemic CRVO or when neovascular glaucoma threatens. The procedure is done in the office and is well tolerated.
Controlling blood pressure, blood sugar, and cholesterol helps protect the retina and lowers the chance of CRVO affecting your other eye. Your retina specialist may work with your primary care doctor to coordinate care.
Regular eye exams are essential to catch complications early and adjust treatment as needed. OCT imaging and dilated exams help track how your retina is responding. Learn more about ongoing retinal vein occlusion management and what to expect during follow-up visits.
What to Expect After Diagnosis
Some people recover much of their vision, especially with early treatment. Others may have lasting vision loss, depending on how severe the blockage was and how quickly treatment began. Your retina specialist will help you understand what to expect based on your specific case.
Magnifiers, brighter lighting, large-print materials, and electronic readers can make daily tasks easier. Low-vision specialists can suggest tools and strategies to help you stay independent.
A heart-healthy lifestyle supports your eyes and lowers the risk of future problems.
- Eat plenty of vegetables, fruits, fish, and whole grains
- Stay physically active as your health allows
- Quit smoking
- Keep blood pressure, blood sugar, and cholesterol in a healthy range
- Limit alcohol
Vision changes can be stressful. Talking with family, friends, a counselor, or a support group can help you cope. Your care team can connect you with resources if you need extra support.
Frequently Asked Questions
CRVO usually occurs in one eye at a time. About 10 percent of people develop it in their other eye over time. Managing risk factors like blood pressure and diabetes helps lower this chance.
Any sudden, painless vision loss should be evaluated as soon as possible. Early diagnosis and treatment give you the best chance of protecting your vision.
The number of injections varies. Some people need ongoing treatment, while others improve and can be monitored without frequent injections. Your retina specialist will adjust your plan based on how your eye responds.
CRVO is sometimes called a type of eye stroke, but it affects a vein, not an artery. Central retinal artery occlusion blocks the artery and causes sudden, severe vision loss that is harder to treat. Both conditions need urgent attention.
Yes. Quitting smoking, eating well, staying active, and controlling blood pressure, blood sugar, and cholesterol can support your overall eye health and may lower the risk of complications.
Glasses and contacts correct focusing problems but cannot restore vision lost from retinal damage. Low-vision aids and rehabilitation services can help you make the most of your remaining sight.
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