CENTRAL RETINAL ARTERY OCCLUSION
What is Central Retinal Artery Occlusion?
Central Retinal Artery Occlusion (CRAO) is an ocular and medical emergency. It is essentially a stroke of the eyes and may be associated with a cerebral stroke and requires immediate attention.
CRAO occurs when the flow of blood through the central retinal artery is blocked (occluded).
Who Does Central Retinal Artery Occlusion Affect?
Cerebral retinal artery occlusion can occur in men or women, usually above the age of 60, and is associated with cardiovascular disease risk factors.
How Does Central Retinal Artery Occlusion Occur?
Central retinal artery occlusion occurs due to obstruction to the retinal blood flow. There are several different causes of this occlusion, these can include:
- thrombus formation or an embolus (clot) causing occlusion. The origin of the clot is usually the carotid artery or the heart
- trauma
- vasculitis.
Causes of Central Retinal Artery Occlusion?
There are multiple risk factors and causes associated with CRAO and most of them are identical to ischemic stroke causes. These causes are:
- High blood pressure (Hypertension)
- Obesity
- Diabetes
- Smoking
- High cholesterol (Hyperlipidemia)
- Coagulopathy disorders
- Male gender
- Age above 60
- Cardiovascular disease e.g. atrial fibrillation
When the retina is oxygen-starved during the blockage, severe vision loss occurs in the affected ischemic area.
Symptoms of Central Retinal Artery Occlusion
The telltale presenting complaint of CRAO is a sudden onset, painless, persistent monocular vision loss.
This vision loss can range from mild to the inability to count fingers to light perception.
Types of Central Retinal Artery Occlusion
The artery blockage (ischemic region) may vary according to where occlusion occurs, and the causative pre-existing condition may be different, but the presentation, symptoms and prognosis remain the same.
Visual loss in CRAO is proportional to the amount of retina that is starved of oxygen.
How is Central Retinal Artery Occlusion Diagnosed?
Diagnosis depends on
- Eye Examination
- Optical Coherence Topography (OCT) is used to visualize retinal atrophy and swelling.
- Fluorescein angiography
A complete systemic examination should also be done including carotid artery imaging to determine if there is carotid artery atherosclerosis.
How is Central Retinal Artery Occlusion Treated?
There is controversy regarding treatment options. In general, treatment is targeted at preventing further vision loss, and to protect the other eye. These include:
- pharmacological (systemic steroids, anticoagulation therapy, medicines to reduce intraocular pressure)
- ocular massage,
- hyperbaric oxygen therapy and
- carbogen inhalation therapy.
Treatment is often undertaken in conjunction with your general practitioner, cardiologist, and neurologist.
Unfortunately the prognosis is poor and there is usually little recovery of vision. The underlying causes may also increase risk of a cerebral stroke.
