Central Retinal Artery or Vein Occlusion

The retina requires a constant supply of oxygen and nutrients delivered through its blood vessels. When the central retinal artery (CRAO) or central retinal vein (CRVO) becomes blocked, it disrupts this vital blood flow, causing retinal tissue damage and vision loss.

Central retinal artery occlusion blocks blood flow into the retina, causing immediate and severe vision loss. Central retinal vein occlusion blocks blood flow out of the retina, leading to swelling, bleeding, and gradual vision impairment. Both conditions often occur in people with underlying cardiovascular disease.

These conditions are medical emergencies that require prompt diagnosis and treatment. Early intervention within the first few hours may help preserve some vision, while delayed treatment often results in permanent vision loss. The condition may also indicate underlying systemic health problems that need immediate attention.

Symptoms of retinal vascular occlusion typically appear suddenly and may be accompanied by systemic symptoms, particularly irregular heartbeat, which could indicate an underlying cardiovascular emergency.

Primary Visual Symptoms

• Diminished vision - sudden, severe reduction in sight
• Blindness - complete or near-complete vision loss
• Symptoms of eye - various eye-related complaints
• Visual field defects - loss of peripheral or central vision
• Sudden onset of vision loss (minutes to hours)
• Painless vision loss in most cases

Associated Eye Symptoms

• Pain in eye - may occur with increased pressure
• Foreign body sensation in eye - feeling of something in the eye
• Flashing lights or floaters before vision loss
• Light sensitivity in some cases
• Pupil abnormalities
• Loss of color vision

Systemic Warning Signs

• Irregular heartbeat - may indicate cardiovascular emergency
• Chest pain or discomfort
• Shortness of breath
• Dizziness or fainting
• Sudden weakness on one side of body
• Speech difficulties

Differences Between CRAO and CRVO

Retinal vascular occlusions are typically caused by blood clots, emboli, or vessel inflammation that blocks normal blood flow. Understanding risk factors is crucial for prevention and early detection.

Primary Causes

• Embolic Occlusion: Blood clots from heart or carotid arteries
• Thrombotic Occlusion: Local clot formation in retinal vessels
• Arterial Spasm: Temporary vessel constriction
• Inflammatory Conditions: Vasculitis affecting retinal vessels
• Compression: Increased intraocular pressure

Cardiovascular Risk Factors

• Hypertension: High blood pressure damages vessel walls
• Diabetes: Causes retinal blood vessel damage
• Atherosclerosis: Arterial plaque increases emboli risk
• Heart Disease: Atrial fibrillation, valve disease
• Carotid Artery Disease: Source of emboli to retinal arteries
• High Cholesterol: Contributes to vascular disease

Other Risk Factors

• Age: More common in people over 60
• Gender: Slightly more common in men
• Smoking: Increases clotting and vascular damage
• Glaucoma: Increased eye pressure
• Blood Disorders: Clotting abnormalities
• Vasculitis: Inflammatory blood vessel disease
• Oral Contraceptives: May increase clotting risk
• Migraine: Vascular changes may contribute

Emergency Precipitants

• Sudden blood pressure spikes
• Heart rhythm abnormalities
• Dehydration or blood loss
• Recent surgery or trauma
• Sudden physical exertion

Retinal vascular occlusion is an ophthalmologic emergency. Rapid diagnosis and treatment within the first few hours are critical for preserving vision and identifying life-threatening underlying conditions.

Immediate Diagnostic Tests

• Ophthalmoscopy: Direct visualization of retinal blood vessels
• Visual Acuity Testing: Assess degree of vision loss
• Visual Field Testing: Map areas of vision loss
• Fluorescein Angiography: Evaluate blood flow in retinal vessels
• OCT (Optical Coherence Tomography): Assess retinal structure
• Intraocular Pressure: Rule out glaucoma

Systemic Evaluation

• Cardiovascular Assessment: ECG, blood pressure, heart rhythm
• Carotid Ultrasound: Check for artery blockages
• Blood Tests: Complete blood count, clotting studies, glucose
• Echocardiogram: Evaluate heart function and valve disease
• Neurological Exam: Rule out stroke

Emergency Treatments

For Central Retinal Artery Occlusion (CRAO)

• Ocular Massage: May help dislodge emboli
• Anterior Chamber Paracentesis: Reduce eye pressure
• Hyperbaric Oxygen: Increase oxygen delivery
• Vasodilators: Improve blood flow
• Thrombolytic Therapy: In select cases within hours

For Central Retinal Vein Occlusion (CRVO)

• Anti-VEGF Injections: Reduce retinal swelling
• Corticosteroid Injections: Control inflammation
• Laser Photocoagulation: Prevent complications
• Monitor for Neovascularization: Prevent glaucoma

After emergency treatment, ongoing management focuses on preventing complications, preserving remaining vision, and addressing underlying cardiovascular risk factors.

Ophthalmologic Follow-up

• Regular retinal examinations
• Monitoring for neovascularization
• Managing secondary glaucoma
• Treating macular edema
• Vision rehabilitation services
• Low vision aids and training

Cardiovascular Management

• Antiplatelet Therapy: Aspirin or clopidogrel
• Blood Pressure Control: Target <140/90 mmHg
• Diabetes Management: Tight glucose control
• Cholesterol Management: Statin therapy
• Smoking Cessation: Eliminate tobacco use
• Heart Rhythm Management: Treat atrial fibrillation

Ongoing Treatments

• Intravitreal Injections: Anti-VEGF or steroids
• Laser Therapy: Prevent complications
• Surgical Options: Vitrectomy in severe cases
• Implantable Devices: Sustained-release medications

Without proper management, retinal vascular occlusions can lead to serious complications affecting both vision and overall health:

Ocular Complications

• Permanent Vision Loss: Irreversible damage to retinal tissue
• Neovascular Glaucoma: Abnormal blood vessel growth
• Vitreous Hemorrhage: Bleeding into eye's gel-like interior
• Retinal Detachment: Separation of retinal layers
• Macular Edema: Swelling of central retina
• Cystoid Macular Edema: Fluid accumulation in macula

Systemic Complications

• Stroke: Brain blood vessel occlusion
• Heart Attack: Coronary artery blockage
• Carotid Artery Disease: Neck artery narrowing
• Cardiovascular Death: From underlying heart disease
• Recurrent Occlusions: In same or opposite eye

The prognosis for retinal vascular occlusion varies significantly based on the type of occlusion, severity, timing of treatment, and underlying health conditions:

Central Retinal Artery Occlusion (CRAO)

• Generally poor prognosis for vision recovery
• Only 10-20% of patients regain useful vision
• Earlier treatment improves outcomes
• May retain some peripheral vision
• High risk of cardiovascular events

Central Retinal Vein Occlusion (CRVO)

• Better prognosis than CRAO
• 30-50% of patients improve with treatment
• Response depends on severity of initial vision loss
• May develop complications requiring ongoing treatment
• Risk of recurrence in same or opposite eye

Factors Affecting Recovery

• Time from symptom onset to treatment
• Initial severity of vision loss
• Patient age and overall health
• Presence of other eye conditions
• Response to initial treatments
• Control of underlying risk factors