Retinal Vein Occlusion (Eye Stroke): Causes, Symptoms, Diagnosis, and Treatment

Primary Keyword: Retinal Vein Occlusion (RVO)

Secondary Keywords: Branch Retinal Vein Occlusion (BRVO), Central Retinal Vein Occlusion (CRVO), retinal vein blockage, eye stroke, retinal vascular disease

A Retinal Vein Occlusion (RVO) is one of the most common retinal vascular disorders and is often referred to as an eye stroke. It occurs when one of the veins responsible for draining blood from the retina becomes blocked. This blockage causes blood and fluid to leak into the retina, leading to swelling, haemorrhages, and vision loss.

Retinal vein occlusion is the second most common retinal vascular disease after diabetic retinopathy and primarily affects adults over 50 years of age. Early diagnosis and modern treatments—especially anti-VEGF injections—have significantly improved visual outcomes for many patients.

In this comprehensive guide, you'll learn everything about retinal vein occlusion, including its types, causes, symptoms, diagnosis, treatment options, prognosis, and prevention.

What Is Retinal Vein Occlusion (RVO)?

The retina is a thin layer of light-sensitive tissue located at the back of the eye. It requires a constant supply of oxygen-rich blood through retinal arteries, while retinal veins drain oxygen-poor blood away.

A Retinal Vein Occlusion (RVO) occurs when one of these retinal veins becomes blocked by a blood clot or is compressed by an adjacent artery.

As a result:

• Blood cannot drain properly.
• Pressure builds inside the retinal veins.
• Blood leaks into the retina.
• Fluid accumulates, causing retinal swelling (macular oedema).
• Vision becomes blurred or decreases.

Unlike a retinal artery occlusion, which blocks oxygen entering the retina, retinal vein occlusion affects blood drainage.

How Does Retinal Vein Occlusion Develop?

Normal circulation:

Heart → Retinal Artery → Retina → Retinal Vein → Heart

After blockage:

Blocked retinal vein → Blood backs up → Haemorrhage → Macular oedema → Vision loss

Types of Retinal Vein Occlusion

1. Central Retinal Vein Occlusion (CRVO)

CRVO occurs when the main retinal vein becomes blocked.

Features

• Entire retina affected
• Sudden blurred vision
• Extensive retinal haemorrhages
• Higher risk of complications
• Greater likelihood of severe vision loss

2. Branch Retinal Vein Occlusion (BRVO)

BRVO occurs when one branch of the retinal vein becomes blocked.

Features

• Only part of the retina is affected
• Vision loss depends on blockage location
• Better prognosis than CRVO
• Most common type of retinal vein occlusion

Causes of Retinal Vein Occlusion

Several medical conditions increase the risk of retinal vein blockage.

Atherosclerosis

Hardening of arteries compresses nearby retinal veins.

High Blood Pressure

Hypertension damages retinal blood vessels and is the most important risk factor.

Diabetes Mellitus

High blood sugar weakens retinal vessels and promotes clot formation.

High Cholesterol

Fat deposits increase vascular narrowing.

Glaucoma

Raised intraocular pressure increases the risk of CRVO.

Blood Clotting Disorders

Examples include:

• Antiphospholipid syndrome
• Hyperhomocysteinaemia
• Protein C deficiency
• Protein S deficiency

Smoking

Smoking damages blood vessels and increases clot formation.

Age

Most patients are older than 50 years.

Risk Factors

You are more likely to develop retinal vein occlusion if you have:

• High blood pressure
• Diabetes
• High cholesterol
• Glaucoma
• Smoking history
• Obesity
• Cardiovascular disease
• Blood clotting disorders
• Increasing age

Symptoms of Retinal Vein Occlusion

Symptoms depend on the severity and location of the blockage.

Sudden Blurred Vision

Most patients notice blurred vision in one eye.

Painless Vision Loss

Unlike eye infections, retinal vein occlusion usually causes no pain.

Distorted Vision

Straight lines may appear wavy because of macular oedema.

Floaters

Some patients notice dark spots caused by retinal haemorrhages.

Peripheral Vision Loss

More common in branch retinal vein occlusion.

Signs Seen During Eye Examination

An ophthalmologist may observe:

• Flame-shaped retinal haemorrhages
• Dilated tortuous retinal veins
• Cotton wool spots
• Optic disc swelling
• Macular oedema

The classic appearance of CRVO is often described as a "blood and thunder" fundus due to widespread retinal haemorrhages.

How Is Retinal Vein Occlusion Diagnosed?

Early diagnosis helps prevent permanent retinal damage.

Comprehensive Eye Examination

Includes:

• Visual acuity
• Pupillary reactions
• Intraocular pressure
• Dilated retinal examination

Fundus Photography

Fundus photographs document:

• Retinal haemorrhages
• Vein dilation
• Macular oedema
• Disease progression

Optical Coherence Tomography (OCT)

OCT is the gold standard for evaluating macular oedema.

It shows:

• Retinal swelling
• Intraretinal fluid
• Cystoid macular oedema
• Treatment response

Fluorescein Angiography (FA)

FA identifies:

• Areas of poor blood flow
• Capillary non-perfusion
• Retinal leakage
• Neovascularisation

OCT Angiography (OCTA)

A non-invasive method for evaluating retinal blood flow without dye.

Additional Medical Tests

Doctors may recommend:

• Blood pressure measurement
• Blood glucose testing
• Lipid profile
• Blood clotting investigations
• Glaucoma assessment

Treatment of Retinal Vein Occlusion

Treatment aims to reduce retinal swelling, improve vision, and prevent complications.

Anti-VEGF Injections

Anti-VEGF therapy is the first-line treatment for macular oedema caused by retinal vein occlusion.

Common medications include:

• Ranibizumab
• Aflibercept
• Bevacizumab
• Faricimab

Benefits

• Reduces retinal swelling
• Improves visual acuity
• Prevents further vision loss
• May require repeated injections

Steroid Injections

Steroids may be considered in selected patients who do not respond adequately to anti-VEGF therapy or when anti-VEGF treatment is not suitable.

Examples include:

• Dexamethasone implant
• Triamcinolone

Possible side effects include increased intraocular pressure and cataract formation.

Laser Photocoagulation

Laser treatment may be used to:

• Treat retinal neovascularisation
• Reduce complications in ischaemic disease
• Manage selected cases of BRVO-associated macular oedema

Laser is less commonly used as the primary treatment for macular oedema today because anti-VEGF therapy generally provides better visual outcomes.

Management of Underlying Disease

Treatment also includes controlling:

• Blood pressure
• Diabetes
• High cholesterol
• Glaucoma

Lifestyle changes such as stopping smoking and maintaining a healthy diet are also important.

Possible Complications

Without treatment, retinal vein occlusion may lead to:

• Macular oedema
• Retinal neovascularisation
• Vitreous haemorrhage
• Neovascular glaucoma
• Permanent vision loss
• Retinal ischaemia

Recovery and Prognosis

Visual recovery depends on:

• Type of retinal vein occlusion
• Severity of blockage
• Presence of macular oedema
• Degree of retinal ischaemia
• Speed of treatment

BRVO Prognosis

Most patients have a relatively favourable outcome, especially with early anti-VEGF treatment.

CRVO Prognosis

CRVO generally carries a poorer prognosis due to more widespread retinal involvement and a higher risk of complications.

Regular follow-up with OCT imaging is essential to monitor response to treatment.

Can Retinal Vein Occlusion Be Prevented?

Although not all cases are preventable, the risk can be reduced by:

• Controlling blood pressure
• Managing diabetes
• Lowering cholesterol
• Treating glaucoma
• Maintaining a healthy weight
• Exercising regularly
• Quitting smoking
• Having regular eye examinations
• Following treatment for heart and vascular disease

Frequently Asked Questions

Is retinal vein occlusion the same as an eye stroke?

Yes. Retinal vein occlusion is commonly referred to as an eye stroke because it results from a blockage of a retinal blood vessel that disrupts normal retinal circulation.

What is the difference between CRVO and BRVO?

• CRVO (Central Retinal Vein Occlusion): The main retinal vein is blocked, affecting the entire retina and often causing more severe vision loss.
• BRVO (Branch Retinal Vein Occlusion): Only one branch of the retinal vein is blocked, affecting a limited area of the retina with generally a better prognosis.

Can retinal vein occlusion cause blindness?

Yes. If left untreated, complications such as macular oedema, retinal ischaemia, and neovascular glaucoma can lead to permanent vision loss.

Are anti-VEGF injections effective?

Yes. Anti-VEGF injections are considered the standard first-line treatment for macular oedema due to retinal vein occlusion and have significantly improved visual outcomes for many patients.

Can retinal vein occlusion happen again?

Yes. Recurrence can occur in the same eye or the other eye, particularly if underlying risk factors such as hypertension, diabetes, or glaucoma are not well controlled.

Key Takeaways

• Retinal Vein Occlusion (RVO) is a common retinal vascular disorder and a form of eye stroke caused by blockage of a retinal vein.
• The two main types are Central Retinal Vein Occlusion (CRVO) and Branch Retinal Vein Occlusion (BRVO).
• Symptoms typically include sudden painless blurred vision, distorted vision, or vision loss in one eye.
• Diagnosis relies on fundus examination, OCT, fundus photography, and fluorescein angiography.
• Anti-VEGF injections are the primary treatment for macular oedema, while laser therapy and steroids may be used in selected cases.
• Early diagnosis, prompt treatment, and control of systemic conditions such as hypertension, diabetes, and glaucoma are essential for preserving vision and improving long-term outcomes.