Central Retinal Artery Occlusion (CRAO) is a condition where blood flow to the retina is suddenly blocked. As a result, the retinal cells are deprived of oxygen, leading to sudden vision loss.
CRAO is considered an “eye stroke” and is classified as an ocular emergency, requiring immediate medical attention.
Symptoms of CRAO
Common symptoms include:
- Sudden loss of vision
- Vision going dark within seconds
- Usually affects one eye only
- Typically no eye pain
Some patients may experience temporary vision loss that returns within minutes before the actual event. This is called amaurosis fugax and may be a warning sign of an impending blockage.
CRAO and Brain Stroke
Studies show that up to 30% of CRAO patients may also have a brain stroke, sometimes without obvious neurological symptoms.
Therefore, patients with CRAO should undergo evaluation of:
- Brain blood vessels
- Cardiovascular system
Stroke Warning Signs (BE FAST)
You can recognize stroke symptoms using BE FAST:
- B – Balance: Sudden loss of balance
- E – Eyes: Sudden vision changes or loss
- F – Face: Facial drooping
- A – Arm: Weakness in arms or legs
- S – Speech: Slurred or difficult speech
- T – Time: Seek medical help immediately
Time is critical
Why Immediate Treatment Matters
The retina is highly sensitive to lack of blood supply.
Studies show that permanent damage can occur within about 90 minutes of interrupted blood flow.
Early diagnosis and treatment are crucial to improve the chance of visual recovery.
Causes of CRAO
The most common cause is atherosclerosis (hardening of the arteries).
Key risk factors include:
- High blood pressure
- High cholesterol
- Cardiovascular disease
- Diabetes
- Smoking
A blood clot or cholesterol plaque (embolus) may travel and block the central retinal artery.
Other possible causes:
- Vasculitis (inflammation of blood vessels)
- Autoimmune diseases
Treatment Options
Currently, there is no guaranteed treatment to fully restore vision. However, some treatments may improve outcomes if performed early:
1. Lowering Intraocular Pressure
To improve blood flow to the retina:
- Oral medication (e.g., acetazolamide)
- Eye drops
- Glycerine
In some cases, a procedure called anterior chamber paracentesis may be performed to quickly reduce eye pressure.
2. Ocular Massage
Gentle eye massage may help dislodge the blockage, allowing it to move into smaller vessels.
3. Carbogen Therapy
Breathing a mixture of 95% oxygen and 5% carbon dioxide to increase oxygen delivery.
4. Hyperbaric Oxygen Therapy
Treatment in a high-pressure oxygen chamber to enhance oxygen supply to the retina.
5. Thrombolytic Therapy (rtPA)
A clot-dissolving medication that can be administered:
- Intravenous (IV): within 4.5 hours of symptom onset
- Intra-arterial: within 6–12 hours via catheter directly to the eye artery
When Should You See a Doctor?
Seek immediate medical attention if you experience:
- Sudden blurred vision
- Sudden vision loss
- Loss of vision in one eye without pain
Prompt treatment may improve the chance of visual recovery.
