Eye stroke: Sudden painless loss of vision 

January 18, 2020
The very mention of stroke gets people to think of the brain and the very dramatic act of the arm jerking. However, stroke also extends to other areas beyond the brain, and one other place would be the eye.

Dr K. Sivamalar Consultant Ophthalmologist from Pantai Hospital Kuala Lumpur explained that eye stroke; also known as retinal artery occlusion is caused by a clot or narrowing of the retina's blood vessels. The retina's blood flow is interrupted. Blood and fluid may spill out into the retina and cause swelling. If left untreated, this can result in permanent damage to the retina and loss of sight.

There are four different types of eye strokes, depending on the blood vessel that is affected:
  • Central retinal vein occlusion (CRVO): The retina's main vein becomes blocked.
  • Central retinal artery occlusion (CRAO): The retina's central artery becomes blocked.
  • Branch retinal vein occlusion (BRVO): The retina's small veins become blocked.
  • Branch retinal artery occlusion (BRAO): The retina's small arteries become blocked.

​Who are at risk of an eye stroke?
The risk factors are similar to those of a regular stroke. Persons who have a personal history or family history of atherosclerosis or plaque build-up in the arteries, high blood pressure, high cholesterol, previous heart attack or stroke, chest pain, coronary heart disease, diabetes or a family history of diabetes and glaucoma may have a higher risk of having an eye-stroke.  
Central Retinal Vein Occlusion (CRVO)
Blockage in the main retinal vein is called a central retinal vein occlusion (CRVO). When the vein is blocked, blood and fluid begin to spill out into the retina. The macula can swell from this fluid, affecting your central vision. Eventually, without blood circulation, nerve cells in the eye can die leading to loss of more vision.
 
Branch Retinal Vein Occlusion (BRVO)
Similar to central retinal vein occlusion, BRVO happens when branches of the retinal vein become blocked. When the vein is blocked, blood and fluid spill out into the retina. The macula can swell from this fluid, affecting your central vision. Eventually, without blood circulation, nerve cells in the eye can die and you can lose more vision.
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Symptoms
An eye stroke is usually painless. Often, the first symptom of an eye stroke is the sudden loss of vision or loss of vision in one eye.
 
Vision loss can affect the entire eye or be subtler than that where the person experience a loss of peripheral vision only or have ‘floaters’ appearing as small grey spots around the field of vision. Blurry or distorted vision is also possible. Vision changes can start out mild, then become worse over several hours or days.
 
A cerebral stroke, which affects blood flow to the brain, can also cause sudden vision loss or changes in vision. For this reason, patients who experience painless loss of vision are advised to seek medical attention within 6 – 24 hours of onset in order to avoid irreversible blindness.

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