The retina is the light-sensitive tissue at the back of the eye. It needs a continuous supply of oxygen-rich blood to work properly. When a retinal artery becomes blocked, oxygen delivery falls and retinal cells can be injured.
What is an eye stroke?
An eye stroke usually refers to a retinal vascular occlusion in which blood flow through an artery supplying the retina becomes blocked. When the central retinal artery is affected, it is called central retinal artery occlusion (CRAO). When a smaller branch is affected, it is called branch retinal artery occlusion (BRAO).
The word “stroke” is used because retinal tissue is deprived of oxygen, much like an ischaemic stroke. The affected tissue is the retina rather than the brain, but the event remains important because it can be associated with disease in the blood vessels supplying the brain and heart.
What can cause an eye stroke?
- High blood pressure, diabetes and high cholesterol
- Heart disease or an irregular heart rhythm such as atrial fibrillation
- Smoking, blood-clotting disorders and carotid artery disease
- Inflammatory blood-vessel disease, including giant cell arteritis
- Age-related vascular disease, trauma or other medical conditions
Warning signs you should never ignore
The classic warning sign is sudden vision loss or a major reduction of vision in one eye, often without pain. Vision may look dark, grey, blurred or as if a curtain has appeared.
- Sudden loss of vision in one eye
- A dark or grey area in the visual field
- Sudden severe blurring or dimming
- Sudden loss of part of the field of vision
- A temporary episode of vision loss that comes and goes
How is it diagnosed and treated?
Assessment may include visual acuity, pupil examination, eye pressure, a dilated retinal examination and retinal imaging. OCT can help evaluate retinal structure. When arterial occlusion is suspected, the patient may also need urgent medical or neurological evaluation to look for a source of emboli and address vascular risk.
There is no single treatment appropriate for every eye stroke. The first priority is urgent assessment and treatment of any underlying cause. Long-term care may include blood-pressure control, diabetes management, cholesterol treatment, smoking cessation or management of heart rhythm disorders.
The key message
Retinal artery occlusion can be the first visible sign of a wider vascular problem. Sudden, painless vision loss in one eye is a reason for urgent care — not a symptom to observe at home.
