Central Retinal Artery Occlusion (CRAO)

Central retinal artery occlusion (CRAO) is often described as a "stroke of the eye." It occurs when the main artery supplying blood to the retina becomes blocked, causing sudden, painless, and usually severe vision loss. Like a brain stroke, CRAO is a medical emergency—and it often signals high risk for stroke and heart attack.

What Happens in CRAO

The Central Retinal Artery

• Main blood supply to the inner retina
• Branches off the ophthalmic artery (from the brain's blood supply)
• Enters the eye through the optic nerve
• When blocked, the retina loses oxygen and begins to die

Timeline of Damage

Symptoms

Classic Presentation

• Sudden vision loss—often "like a curtain came down"
• Painless
• Usually one eye
• Severe—often counting fingers or worse
• No warning in most cases (unless previous transient episodes)

Preceding Symptoms (in some patients)

• Amaurosis fugax—transient vision loss lasting seconds to minutes
• Episodes of "shade coming down" that resolved
• These are warning signs that were missed

What You Won't Have

• Pain
• Red eye
• Gradual onset
• Flashing lights (usually)

Causes

Emboli (Most Common)

Material that travels from elsewhere and lodges in the artery:

Sources:

• Carotid artery plaque (atherosclerosis)
• Heart (atrial fibrillation, valve disease, heart attack)
• Aortic arch plaque

Types:

• Cholesterol emboli (Hollenhorst plaques)
• Platelet-fibrin emboli
• Calcific emboli (from heart valves)

Thrombosis

Clot forming in place:

• Atherosclerosis of the retinal artery
• Giant cell arteritis (inflammatory)
• Hypercoagulable states

Giant Cell Arteritis (GCA)

Other Causes

• Vasospasm
• Dissection of carotid or ophthalmic artery
• Trauma
• Complications of procedures (injections, surgery)
• Sickle cell disease

Risk Factors

• Cardiovascular disease (hypertension, diabetes, hyperlipidemia)
• Smoking
• Carotid artery disease
• Cardiac disease (atrial fibrillation, valve disease)
• Age (typically over 60)
• Male sex (slightly higher risk)
• Previous TIA or stroke
• Hypercoagulable states

Diagnosis

Clinical Examination

What the Doctor Sees:

• Severely reduced visual acuity (often counting fingers or worse)
• Afferent pupillary defect (pupil doesn't react normally to light)
• Pale, white retina (ischemic)
• "Cherry red spot" at the macula (classic finding)
• Narrowed, "boxcarring" arteries
• May see embolus in artery

The "Cherry Red Spot"

• The macula appears red against the surrounding pale retina
• Occurs because the macula is thin enough to show underlying choroidal blood supply
• Classic but not always present (especially early)

Urgent Testing

Immediate:

• ESR and CRP (to rule out giant cell arteritis)
• Blood pressure
• Blood glucose
• Complete blood count
• Coagulation studies

Urgent Workup:

• Carotid ultrasound or CTA
• Echocardiogram (looking for cardiac source)
• ECG (looking for atrial fibrillation)
• MRI/MRA brain (if stroke symptoms or GCA suspected)
• Temporal artery biopsy (if GCA suspected)

Differential Diagnosis

• Ophthalmic artery occlusion (even more severe)
• Central retinal vein occlusion (different appearance)
• Optic neuritis
• Vitreous hemorrhage

Treatment

The Reality of Treatment

Attempted Treatments (Variable Evidence)

Historical/Traditional:

• Ocular massage (attempt to dislodge embolus)
• Anterior chamber paracentesis (lower eye pressure)
• Carbogen inhalation (increase oxygen)
• Hyperbaric oxygen (limited availability, time-sensitive)

Newer Approaches (Under Investigation):

• Intra-arterial thrombolysis (clot-busting drugs delivered directly)
• IV thrombolysis (systemic tPA, as for stroke)
• Results have been mixed; may be considered within hours

What IS Critical

Stroke Prevention: The most important intervention is preventing brain stroke and heart attack:

• Urgent cardiovascular workup
• Carotid evaluation
• Cardiac evaluation
• Risk factor modification
• Antiplatelet therapy (Aspirin)
• Anticoagulation if indicated (atrial fibrillation)
• Statin therapy

If Giant Cell Arteritis Suspected:

• Immediate high-dose IV steroids
• Can prevent blindness in the other eye
• Temporal artery biopsy (doesn't delay treatment)

Prognosis

Visual Outcome

• Most patients do not regain useful vision
• Only 10-20% have significant improvement
• Final vision often counting fingers or worse
• Some patients retain peripheral vision if cilioretinal artery present

Systemic Implications

Living with Vision Loss

Practical Considerations

• Register with low vision services
• Occupational therapy for daily activities
• Evaluate driving ability (usually cannot drive with severe loss in one eye)
• Protect the remaining eye

Psychological Support

• Vision loss is traumatic
• Counseling may help
• Connect with support groups
• Focus on what can be done for prevention

Prevention

For Those at Risk

• Control blood pressure
• Control diabetes
• Control cholesterol
• Stop smoking
• Take prescribed medications
• Regular cardiovascular checkups

Warning Signs

If you experience transient vision loss (amaurosis fugax):

• Seek immediate medical attention
• This may be a warning of impending CRAO or stroke
• Urgent workup needed

Frequently Asked Questions

Is there any chance my vision will come back?

Unfortunately, most patients do not regain useful vision after CRAO. The retina suffers irreversible damage very quickly without blood flow. Some patients have modest improvement, and rarely patients with a cilioretinal artery retain some central vision.

Why do I need so many heart and brain tests?

CRAO is often caused by the same problems that cause stroke and heart attack—blocked arteries and blood clots. Finding and treating these problems can prevent a devastating brain stroke, which is actually the bigger risk after CRAO.

Am I going to have a stroke?

CRAO significantly increases stroke risk, which is why urgent workup and prevention are so important. With proper evaluation and treatment of risk factors, this risk can be reduced. This is the silver lining—you've received a warning that allows preventive action.

Will my other eye be affected?

The same risk factors that caused CRAO in one eye do put the other eye at risk. This is another reason why risk factor modification and treatment are so important. If giant cell arteritis is the cause, the other eye is at high, imminent risk without treatment.

What can I do now?

Focus on what you can control: follow up with cardiology and neurology, take prescribed medications, modify risk factors (smoking, diet, exercise), and work with low vision services to maximize function with your remaining vision.

References