Suraj Eye Institute · Medical Retina
Retinal Vein Occlusion (CRVO & BRVO)
EN: A sudden, painless “stroke” in the eye’s drainageहिंदी: रेटिनल वेन ऑक्लूज़नमराठी: रेटिनल व्हेन ऑक्लुजन
Retinal Vein Occlusion (CRVO & BRVO)
Retinal Vein Occlusion is a “blockage” in one of the small veins that drain blood out of the retina. When the vein is blocked, blood and fluid back up, causing sudden blurring, swelling and bleeding inside the eye. It is one of the most common vascular emergencies of the retina and the second-leading cause of vision loss from retinal vascular disease, after diabetic retinopathy.
A retinal vein occlusion is a “stroke” in the eye’s drainage system. The vision loss is sudden, painless and often noticed when waking up in the morning or covering one eye accidentally.
What Happens Inside the Eye
Each retina is drained by a network of small veins that come together to form the central retinal vein at the optic nerve. If a vein becomes narrowed by an artery pressing against it (often at a crossing point), a clot can form and block flow. Blood backs up behind the block, leading to:
- Haemorrhages spreading across the retina
- Swelling of the macula (macular edema)
- Lack of oxygen in the affected area
- In severe cases, growth of abnormal new vessels and a dangerous form of glaucoma
In BRVO the blockage occurs at an artery–vein crossing point and bleeds are confined to one sector. In CRVO the entire central vein is blocked and bleeds spread across the whole retina, with a swollen optic disc.
The Two Main Types
- Branch Retinal Vein Occlusion (BRVO) — a smaller, sector-supplying vein is blocked. Bleeding and swelling are limited to one quadrant of the retina. Vision is affected only if the macula is involved.
- Central Retinal Vein Occlusion (CRVO) — the main central vein is blocked at the optic nerve. The entire retina is affected. Vision drops dramatically and more severely.
- Hemiretinal Vein Occlusion (HRVO) — a less common variant where the upper or lower half of the retina is involved.
Symptoms
- Sudden, painless drop in vision in one eye — often noticed on waking up
- A dark patch or shadow over part of the vision
- Distortion of straight lines
- Floaters (if there is associated vitreous bleed)
- Rarely, deep aching pain weeks later if neovascular glaucoma develops
Who Is at Risk?
- High blood pressure — by far the most common association
- Diabetes mellitus
- High cholesterol or atherosclerosis
- Glaucoma — high eye pressure compresses veins at the optic nerve
- Smoking
- Obstructive sleep apnoea
- Inflammatory or clotting disorders (in younger patients)
- Oral contraceptives, hormone replacement therapy
- Age above 50 (most cases), though younger patients can be affected
A vein occlusion is often the first sign of undiagnosed high blood pressure or diabetes. Every patient with RVO needs a full systemic workup.
How We Diagnose RVO
- Dilated retinal examination — the diagnosis is usually obvious on fundus examination
- OCT — measures macular swelling and follows treatment response
- OCT-Angiography — non-invasively maps areas of poor blood flow (non-perfusion)
- Fluorescein angiography — the most detailed map of the non-perfusion zones and any new vessels
- Ultra-widefield fundus imaging — valuable for following large peripheral non-perfusion
- Systemic workup — BP, blood sugar, lipids, kidney function; in selected patients, sleep study or clotting profile
Treatment Options
- Intravitreal anti-VEGF injections — the first-line treatment for the macular swelling that causes vision loss in both CRVO and BRVO. Aflibercept, Ranibizumab, Brolucizumab, Faricimab and Bevacizumab are all used.
- Intravitreal steroid implants (Ozurdex) — helpful in selected patients, particularly those who cannot return for frequent injections.
- Retinal laser (sector or pan-retinal) — for large non-perfusion areas or when new vessels develop. Treatment is targeted at preventing neovascular glaucoma.
- Surgery — rarely needed, for non-clearing vitreous haemorrhage or tractional changes.
- Control of underlying systemic disease — BP, diabetes and lipid management are essential to protect the other eye.
What to Expect from Treatment
| BRVO | CRVO | |
|---|---|---|
| Severity of vision loss | Moderate, limited to the affected sector | Severe; whole field affected |
| Risk of new vessels | Lower but possible | Higher, especially in ischaemic CRVO |
| Treatment | Anti-VEGF for macular oedema ± sector laser | Anti-VEGF or steroid for oedema ± full PRP if ischaemic |
| Visual prognosis | Usually good with treatment | Variable; depends on perfusion |
| Follow-up | Months to years | Lifelong |
Prevention & Self-Care
- Control blood pressure — this is the single most important step to protect the other eye
- Diabetes and cholesterol control
- Stop smoking
- Healthy weight, regular exercise
- Treat sleep apnoea if present
- If you have glaucoma, keep eye pressure controlled
- Yearly eye and systemic check-up
When to Come to Us Immediately
Sudden painless blurring in one eye, a new dark patch, or worsening of an old occlusion — come the same day. Early anti-VEGF treatment gives the best visual recovery.
In short: A retinal vein occlusion is a sudden, painless “stroke” of the eye’s drainage. With prompt anti-VEGF treatment and tight control of blood pressure, most patients keep useful vision — and protect their other eye for life.
Frequently Asked Questions
I had no warning at all. Why did this happen suddenly?
Vein occlusions almost always happen suddenly. Underlying risk factors (high blood pressure, diabetes, glaucoma) build up silently for years before the vein eventually blocks.
Can the blocked vein be opened again?
Generally no — the focus of treatment is on the consequences (swelling, lack of blood flow, new vessels). Modern injections allow most patients to regain useful vision even though the vein itself does not re-open.
Will it happen in my other eye?
The risk is higher than in someone who never had RVO. Tight control of blood pressure, sugar and cholesterol — and treatment of glaucoma if present — significantly reduces this risk.
How long do I need injections?
It varies. Many patients need monthly injections initially, then the interval is gradually extended. Some need long-term injections, others can be stopped. Each eye is followed individually with OCT.
Do I need any blood tests?
Yes — blood pressure, fasting sugar / HbA1c, lipid profile and kidney function. Younger patients may need clotting tests and screening for inflammatory disease.
Is there a risk of complete blindness?
Most patients keep useful vision with modern treatment. The main long-term threat is neovascular glaucoma in severe CRVO — which is why follow-up matters even after the swelling has settled.
Book an appointment for a retina evaluation at Suraj Eye Institute.
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