Retinal Vein Occlusion: Risk Factors and Injections Explained

What Is Retinal Vein Occlusion?

Retinal vein occlusion (RVO) happens when a vein in the retina gets blocked, stopping blood from flowing out. This causes fluid and blood to leak into the retina, leading to swelling and vision loss. It’s not painful, but it can hit suddenly - one day your vision is fine, the next it’s blurry or dark in part of your eye.

There are two main types: central retinal vein occlusion (CRVO), which blocks the main vein, and branch retinal vein occlusion (BRVO), which affects smaller branches. CRVO is more serious and often leads to worse vision loss. BRVO tends to affect only part of your vision, like the top or bottom half of your visual field.

It’s not rare. Around 16.4 million people worldwide have it, and most are over 55. But it can happen to younger people too - about 1 in 10 cases are under 45. The retina doesn’t heal on its own, so without treatment, vision can keep getting worse.

What Causes Retinal Vein Occlusion?

The blockage usually comes from a clot, but that clot doesn’t just appear out of nowhere. It’s tied to what’s happening in your blood vessels and overall health.

The biggest risk factor is high blood pressure. Up to 73% of people over 50 with CRVO have uncontrolled hypertension. Even if you don’t feel sick, high pressure inside your blood vessels can damage the thin walls of the retinal veins. That makes them more likely to narrow or get blocked.

Diabetes is another major player. About 10% of RVO patients over 50 have diabetes. High blood sugar damages blood vessels over time, making them stiff and more prone to clots. People with diabetes also tend to have worse outcomes after RVO.

High cholesterol plays a role too. If your total cholesterol is above 6.5 mmol/L, your risk goes up. That’s because fatty deposits can build up in arteries, and when a hardened artery crosses over a vein in the eye, it can squeeze it shut - that’s how BRVO often starts.

Glaucoma increases risk as well. If pressure inside your eye is too high, it can compress the vein at the optic nerve. That’s why people with glaucoma need regular eye checks - RVO can sneak in unnoticed.

Lifestyle matters. Smoking doubles your risk. Being overweight or inactive adds to the strain on your circulation. And for women under 45, birth control pills are a known trigger - especially if they have other risk factors like high blood pressure or clotting disorders.

Less common but serious causes include blood disorders like polycythemia vera (too many red blood cells), multiple myeloma, or inherited clotting problems like factor V Leiden. These are rare, but if you get RVO under 45, your doctor will likely test for them.

How Do Injections Help?

Injecting medicine directly into the eye is now the standard treatment for RVO. Why? Because the main problem isn’t just the blockage - it’s the swelling in the center of the retina, called macular edema. That’s what blurs your vision.

The two main types of injections are anti-VEGF drugs and corticosteroids.

Anti-VEGF drugs like ranibizumab (Lucentis), aflibercept (Eylea), and bevacizumab (Avastin) block a protein called VEGF that causes blood vessels to leak. These injections reduce swelling and often improve vision. In clinical trials, people gained 15 to 20 letters on the eye chart - that’s like going from reading only the top line to reading most of the chart.

Corticosteroid injections, like the dexamethasone implant (Ozurdex), work differently. They reduce inflammation and swelling over a longer period. One implant can last 3 to 6 months. But they come with risks: they can cause cataracts or raise eye pressure, which might need extra treatment.

Doctors usually start with anti-VEGF because it’s safer long-term. Steroids are reserved for people who don’t respond well to anti-VEGF, or those with very severe swelling.

What’s the Treatment Process Like?

Getting an eye injection sounds scary, but it’s quick and routine. Most patients say the fear is worse than the procedure.

First, your eye is numbed with drops. Then the doctor cleans the surface with antiseptic and holds your eyelid open with a tiny clamp. The needle goes in through the white part of your eye - you might feel a little pressure, but not pain. The whole thing takes less than 10 minutes.

Afterward, you might see floaters or have a red spot on your eye. That’s normal. Serious complications like infection (endophthalmitis) happen in fewer than 1 in 1,000 injections.

Most people need injections every 4 to 6 weeks at first. After a few months, if the swelling improves, the schedule can stretch out. Some patients switch to a “treat-and-extend” plan - where they get injections spaced further apart as long as their vision stays stable.

Real-world data shows most people need 8 to 12 injections in the first year. That’s a lot, and it’s why many patients feel overwhelmed. But the payoff is real: 78% of people report major vision improvement after a year of treatment.

Costs and Accessibility

The price of these injections varies wildly. In the U.S., Lucentis and Eylea cost about $2,000 per shot. Avastin, which is used off-label, costs around $50. That’s why many hospitals and clinics use Avastin - it’s just as effective for many patients.

Insurance often covers the branded drugs, but copays can still hit $100-$150 per injection. For someone on a fixed income, that adds up fast. Some patients skip appointments because of cost, even though their vision is improving.

There’s also a new option coming: the Susvimo implant, which slowly releases medicine over months. It’s approved for another eye condition and is being tested for RVO. If it works, it could cut injections from monthly to quarterly - a game-changer for people tired of frequent visits.

What to Expect Long-Term

RVO isn’t cured by injections - it’s managed. Even if your vision improves, you’ll likely need ongoing monitoring. The blockage might heal, but the damage to your blood vessels doesn’t go away. That means you’re still at risk for new clots or swelling down the line.

Regular eye exams with OCT scans are key. These scans measure fluid thickness in the retina. If it goes above 300 micrometers, that’s a sign to restart treatment. If it drops below 250, you might be able to wait longer between injections.

Controlling your risk factors is just as important as the injections. Lowering blood pressure, managing diabetes, quitting smoking, and keeping cholesterol in check can prevent new problems in your eye - and your heart and brain too.

Emerging Treatments and Future Hope

Researchers are working on better ways to treat RVO. One promising area is gene therapy. The drug RGX-314 is being tested to deliver anti-VEGF genes directly into eye cells. If it works, you might only need one treatment that lasts years.

Another new drug, OPT-302, blocks a different VEGF protein and is being tested alongside aflibercept. Early results suggest it helps patients who didn’t respond well to standard treatment.

Doctors are also using advanced imaging to personalize care. Instead of treating everyone the same, they’re looking at patterns in blood flow and swelling to decide who needs steroids, who needs more frequent shots, and who might benefit from combo therapy.

The goal isn’t just to restore vision - it’s to reduce the burden. Fewer injections, fewer visits, fewer side effects. That’s the future.

What You Can Do Now

If you’ve been diagnosed with RVO, the most important thing is to stick with treatment. Vision can improve - even after months of blurry sight. But only if you keep going.

If you haven’t been diagnosed but are over 50 and have high blood pressure, diabetes, or high cholesterol, get your eyes checked yearly. RVO often has no warning signs until it’s too late.

And if you’re under 45 and had RVO? Ask your doctor about blood tests for clotting disorders. It’s rare, but knowing the cause can help prevent future issues.

There’s no magic pill. But with today’s treatments, most people with RVO can keep their vision - and their independence - for years to come.