Central Retinal Vein Occlusion: Causes, Symptoms, and Treatment
What Is Central Retinal Vein Occlusion?
The retina is the thin, light-sensitive layer of tissue at the back of your eye. It depends on a constant supply of blood to function. When the main vein that drains blood from the retina becomes blocked, fluid and blood back up into the retinal tissue, and vision can be seriously affected.
The central retinal vein is the primary drainage vessel for the entire retina. A blockage typically forms at or near the lamina cribrosa, the point where the optic nerve exits the back of the eye. Three main factors contribute to clot formation: slowed blood flow in the vein, damage to the vessel wall, and an increased tendency for blood to clot. Any medical condition that worsens these factors can set off a CRVO.
The central retinal artery and vein share a common outer covering behind the lamina cribrosa. When conditions like high blood pressure or diabetes cause the artery to thicken and harden through a process called atherosclerosis, the artery can compress the nearby vein. This compression slows blood flow, injures the vein wall, and promotes clot formation.
Retina specialists classify CRVO into two main types based on severity. Non-ischemic CRVO is the milder form, in which retinal blood vessels become leaky and fluid collects in the macula (the central part of the retina responsible for sharp detail vision), but overall blood circulation is not severely disrupted. Many patients with this type retain useful vision and respond well to treatment.
Ischemic CRVO is the more severe form. Small retinal blood vessels become completely closed off, cutting blood supply to portions of the retina. Patients with ischemic CRVO tend to have worse vision from the start and a lower chance of significant recovery. This type also carries a higher risk of serious complications, including the growth of fragile, abnormal new blood vessels.
Who Is at Risk for CRVO?
CRVO can affect anyone, but certain health conditions and personal factors raise the risk significantly. Identifying these risk factors is important both for your eye health and for your overall cardiovascular wellbeing.
CRVO most commonly affects people aged 50 and older, with the large majority of cases occurring in patients over the age of 55. The risk continues to rise with each decade of life. While less common, CRVO can also affect younger adults, often with different underlying causes.
High blood pressure is the most common health condition associated with CRVO. It is present in a large majority of CRVO patients over the age of 50. Elevated blood pressure damages the walls of blood vessels throughout the body, including those in the retina, making clot formation more likely.
Diabetes also raises the risk of CRVO by damaging blood vessel walls over time. Managing blood pressure and blood sugar consistently is one of the most important things you can do to lower your risk of retinal vein occlusion and protect your vision long-term.
Several additional conditions and lifestyle factors can increase the likelihood of developing CRVO. Being aware of these can help guide conversations with your doctors about prevention and monitoring.
- Glaucoma, a condition involving increased pressure inside the eye
- Atherosclerosis, the hardening and narrowing of arteries
- Blood clotting disorders, also called hypercoagulable states
- High cholesterol and abnormal lipid levels
- Smoking
- Oral contraceptive use in younger women, which is the most common underlying association with CRVO in this age group
Research has also found that patients with CRVO carry an increased risk of serious cardiovascular events, even after accounting for known risk factors like age, diabetes, and high blood pressure. This means that a CRVO diagnosis should be treated as a signal to evaluate your overall vascular health, not just your vision.
Symptoms of CRVO
Recognizing the symptoms of CRVO early is critical. Prompt evaluation and treatment give you the best chance of preserving your vision. Some symptoms require immediate medical attention.
The most common symptom of CRVO is painless vision loss or blurring in one eye. This can come on suddenly or develop over several hours or days. In some cases, vision loss is severe and rapid. Because the vision change typically affects only one eye, some people do not notice it right away.
Some patients notice floaters, which are dark spots, lines, or drifting shapes in their field of vision. These are caused by tiny amounts of blood that have leaked from retinal vessels into the vitreous, the clear gel that fills the inside of the eye. Floaters that appear suddenly or in large numbers should always be evaluated promptly.
Most cases of CRVO do not cause eye pain. However, in severe cases where CRVO leads to complications such as neovascular glaucoma, a condition in which abnormal new blood vessels grow on the iris and block fluid drainage from the eye, pain, redness, and pressure can develop. These symptoms represent a more advanced and urgent situation.
If you experience sudden vision loss, a rapid increase in floaters, flashes of light, or pain in one eye, seek care from a retina specialist or go to the emergency room right away.
How CRVO Is Diagnosed
Diagnosing CRVO involves a thorough eye examination combined with specialized imaging. Your retina specialist will also look at your overall health to understand the underlying causes and guide treatment planning.
Your retina specialist will begin by checking your visual acuity, which is how clearly you can see at various distances, and measuring the pressure inside your eye. The retina is then examined through a dilated pupil. Dilation involves using eye drops to widen the pupil so that the specialist can clearly view the retina and its blood vessels.
The specialist will look for characteristic signs of CRVO, including swollen and tortuous retinal veins, areas of bleeding scattered throughout the retina, and fluid buildup in the macula.
Optical coherence tomography, commonly called OCT, is a non-invasive imaging test that creates detailed cross-sectional pictures of the retinal layers. OCT allows the specialist to precisely measure the amount of swelling in the macula and track how well your retina is responding to treatment over time.
Fluorescein angiography is another important test. A special dye is injected into a vein in your arm, and a camera takes rapid photographs as the dye travels through the retinal blood vessels. This test helps determine whether you have non-ischemic or ischemic CRVO by identifying areas of blocked blood flow or leaking vessels.
Because CRVO is closely linked to systemic conditions, your retina specialist may recommend blood tests and a referral for a cardiovascular evaluation. Testing for high blood pressure, diabetes, cholesterol levels, and blood clotting disorders helps identify underlying causes and guides your broader treatment plan. Treating these conditions is a key part of managing CRVO and protecting your long-term health.
Treatment Options for CRVO
Treatment for CRVO focuses on reducing swelling in the retina, preserving vision, and preventing complications. The right approach depends on the type and severity of your CRVO and how your eye responds over time.
Anti-VEGF injections are the primary treatment for macular edema (swelling of the macula) caused by CRVO. VEGF stands for vascular endothelial growth factor, a protein that drives abnormal blood vessel growth and fluid leakage in the retina. Anti-VEGF medications are injected directly into the vitreous of the eye to block this protein, reduce swelling, and help stabilize or improve vision.
Two anti-VEGF agents are FDA-approved specifically for macular edema following CRVO: ranibizumab (Lucentis) and aflibercept (Eylea). Bevacizumab (Avastin), approved for cancer treatment, is also widely used in clinical practice for this condition. Treatment typically begins with a series of monthly injections, after which your specialist will adjust the schedule based on how your eye is responding.
Faricimab (Vabysmo) is a newer bispecific antibody that targets both VEGF and a second protein called angiopoietin-2. Clinical studies have shown that faricimab performs comparably to aflibercept in treating CRVO-related macular edema, and it may allow longer intervals between injections for some patients. Your retina specialist can discuss whether this option may be appropriate for your situation.
The dexamethasone implant (Ozurdex) is a small steroid pellet injected into the eye that slowly releases medication over several months. It was the first intravitreal medication specifically approved by the FDA to treat macular edema from retinal vein occlusion. Steroid injections are often considered when patients do not respond adequately to anti-VEGF therapy or when anti-VEGF treatment is not an option.
A known side effect of steroid injections is increased eye pressure, which requires close monitoring during treatment. Steroid implants may also accelerate cataract formation in some patients.
Panretinal photocoagulation, often referred to as PRP, is a laser procedure used in severe ischemic CRVO. When large areas of the retina lose their blood supply, the eye can release signals that trigger the growth of abnormal new blood vessels, a process called neovascularization. These fragile vessels can bleed and lead to serious complications including neovascular glaucoma.
PRP uses a thermal laser to treat areas of the retina that are no longer receiving adequate blood flow, reducing the signals that drive abnormal vessel growth. PRP does not restore central vision, but it plays an important role in preventing and managing the complications of ischemic CRVO.
What to Expect During and After Treatment
Starting treatment for CRVO can feel overwhelming, but understanding what the process involves can help you feel more confident and prepared. Most patients manage well and appreciate knowing what each visit will include.
Intravitreal injections, which are injections directly into the eye, are performed in the office. Before the injection, the eye is numbed with anesthetic drops and cleaned with an antiseptic solution. The injection itself takes only a few seconds. You may feel brief pressure or mild discomfort, but significant pain is uncommon.
After an initial series of monthly loading doses, your retina specialist will evaluate your response using OCT imaging and adjust your schedule accordingly. Some patients are able to gradually extend the time between injections, while others require ongoing monthly treatment to maintain their vision.
Visual outcomes vary depending on the type and severity of CRVO, how quickly treatment is started, and individual factors specific to each patient. Patients with non-ischemic CRVO generally have a better chance of meaningful vision improvement. Those with ischemic CRVO often experience more limited recovery.
Anti-VEGF therapy has substantially improved outcomes for CRVO patients compared to the period before these treatments were available. However, many patients require ongoing injections to maintain the gains they have made. Stopping treatment early can lead to recurrence of macular edema and further vision loss.
Regular follow-up visits are essential after a CRVO diagnosis. Your retina specialist will monitor for signs of worsening, new vessel growth, or returning swelling. Follow-up visits typically include visual acuity testing and OCT imaging at each appointment.
Because non-ischemic CRVO can sometimes convert to the more severe ischemic form over time, ongoing monitoring is important even when your initial condition appears mild. Your specialist will watch closely for signs of this progression and adjust your treatment plan as needed.
Living With CRVO
Managing CRVO goes beyond treating the eye itself. Taking care of your overall health and adapting to any lasting changes in your vision are equally important parts of living well with this condition.
Because CRVO is strongly associated with cardiovascular risk factors, managing your overall health is a critical part of protecting your vision and preventing future events. Work closely with your primary care doctor to keep blood pressure, blood sugar, and cholesterol within healthy ranges. If you smoke, stopping will meaningfully reduce your vascular risk.
Younger women who develop CRVO while taking oral contraceptives should speak with their doctor right away. Since oral contraceptive use is the most common underlying association with CRVO in younger women, continuing this medication after a retinal vein occlusion may not be safe.
CRVO typically affects one eye, but the underlying conditions that caused it can affect both. Controlling blood pressure, diabetes, and other vascular risk factors helps protect your unaffected eye. Report any new visual symptoms in either eye to your retina specialist promptly and do not wait for a scheduled appointment if something feels wrong.
If CRVO has caused lasting changes to your central vision, your retina specialist may refer you to a low vision specialist. Low vision rehabilitation can help you make the most of your remaining sight through magnifying devices, adaptive technology, and training in daily living skills. Good lighting, large-print materials, and high-contrast tools can also make routine tasks much easier.
Sudden vision loss can be frightening and emotionally difficult. It is completely normal to feel anxious, frustrated, or uncertain about your future after a CRVO diagnosis. Connecting with family, joining a support group for people with vision loss, or working with a counselor can provide meaningful help as you adjust.
When to Seek Urgent Eye Care
Certain symptoms related to CRVO require immediate attention. Knowing when to act quickly can make a significant difference in your outcome.
Do not wait for a scheduled appointment if you experience any of the following symptoms. Go directly to a retina specialist or an emergency room right away.
- Sudden vision loss or significant blurring in one eye
- A rapid increase in the number of floaters
- Flashes of light in your vision
- A dark curtain or shadow spreading across your field of vision
- Pain, pressure, or redness in one eye
If you have known risk factors such as high blood pressure, diabetes, glaucoma, or a blood clotting disorder, talk with your doctor about regular dilated eye exams. Retinal vein occlusion can sometimes be detected before significant vision loss occurs. Your primary care doctor or optometrist can screen for early retinal changes and refer you to a retina specialist if there is any concern.
Frequently Asked Questions
These answers address common questions about CRVO that go beyond the basics covered above, including practical guidance on treatment decisions and what to watch for.
CRVO almost always affects one eye at a time. Having it in one eye does increase your risk of developing it in the other eye, particularly if underlying conditions like high blood pressure or diabetes are not well controlled. This is one reason why managing your cardiovascular health after a CRVO diagnosis is so important, and why your specialist will ask about symptoms in both eyes at every visit.
There is no single answer that applies to everyone. Some patients are able to taper down to less frequent injections as macular edema stabilizes, while others need ongoing monthly treatment to maintain their vision. Your retina specialist will use OCT imaging and vision testing at each visit to make this determination. Stopping injections without guidance from your specialist carries a real risk of the swelling returning and vision worsening.
Visual recovery depends on the type of CRVO you have, how much retinal damage occurred before treatment began, and how your eye responds to therapy. Many patients with non-ischemic CRVO experience meaningful improvement in vision with consistent treatment. Patients with ischemic CRVO typically have more limited recovery due to greater damage to the retinal nerve cells. Starting treatment as early as possible gives you the best opportunity to preserve and improve your sight.
CRVO shares many of the same underlying risk factors as heart disease and stroke, including high blood pressure, diabetes, and atherosclerosis. Research has shown that patients diagnosed with CRVO have an elevated risk of serious cardiovascular events compared to the general population. For this reason, your retina specialist may recommend that you see your primary care doctor or a cardiologist for a thorough cardiovascular evaluation after your diagnosis. Treating CRVO as a whole-body warning sign, not just an eye problem, is an important part of your care.
There is no way to guarantee prevention of CRVO, but you can meaningfully lower your risk by managing modifiable health conditions. Keeping blood pressure in a healthy range, controlling blood sugar if you have diabetes, maintaining healthy cholesterol levels, not smoking, and attending regular dilated eye exams all play a role. If you have a known blood clotting disorder, working closely with your physician to manage it is also important. People with existing risk factors benefit most from this proactive approach.
Without treatment, macular edema from CRVO can persist and worsen, leading to permanent damage to the central vision. In severe ischemic CRVO, untreated abnormal new blood vessel growth can lead to neovascular glaucoma, a painful and vision-threatening complication. Early diagnosis and consistent treatment are the most reliable ways to prevent these outcomes and preserve as much vision as possible.
Expert Retina Care at Rhode Island Eye Institute
Rhode Island Eye Institute is home to fellowship-trained retina specialists who provide advanced evaluation and personalized treatment for CRVO and other serious retinal conditions. Our team brings subspecialty expertise, state-of-the-art imaging technology, and a genuine commitment to patient-centered care to every visit. If you are experiencing vision changes or have been told you are at risk for retinal vein occlusion, we encourage you to schedule an appointment with our team and take the first step toward protecting your sight.