FLOATERS AND FLASHES
What Are Eye Floaters?
Floaters are small specks, dots, threads, cobwebs, or squiggly lines that drift across your field of vision.
They are most noticeable when looking at a plain, bright background, such as a clear sky, a white wall, or a computer screen.
Floaters are caused by tiny clumps of collagen fibres or cells within the vitreous, the clear, gel-like substance that fills the inside of the eye between the lens and the retina.
These clumps cast shadows onto the retina, which the brain perceives as floating shapes.
Floaters and Flashes:What You Need to Know
What Are Flashes of Light?
Flashes are brief streaks, sparkles, or flickers of light, often described as similar to a camera flash or lightning. They typically occur when the vitreous gel tugs or pulls on the retina, stimulating it mechanically and causing the retina to send a signal that the brain interprets as light, even though no actual light is present.
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Flashes are most often noticed in dim lighting or in peripheral (side) vision.
Why Do Floaters and Flashes Happen?
The most common cause is a normal age-related process called posterior vitreous detachment (PVD). As we age, the vitreous gel gradually shrinks and becomes more liquid, eventually separating from the surface of the retina. This is extremely common, particularly after the age of 50, and on its own is not usually sight-threatening.
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However, the same process that causes a PVD can, in some cases, also cause a retinal tear. If the vitreous gel is firmly attached to a weak area of the retina, the traction during separation can tear the retinal tissue.
A retinal tear can, in turn, lead to fluid passing through the tear and lifting the retina away from the underlying tissue, a retinal detachment, which requires urgent treatment.
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​Other causes of floaters and flashes include:
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High myopia (short-sightedness), which increases the risk of retinal tears and PVDrelated complications.
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Previous eye surgery, including cataract surgery
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Eye trauma or injury.
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Inflammation inside the eye (uveitis).
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Bleeding within the vitreous (vitreous haemorrhage), which can occur in diabetic eye disease or retinal vein occlusion
When Are Floaters and Flashes a Warning Sign?
Most people experience some floaters at some point, and an occasional floater that has been present and stable for a long time is usually not a cause for concern.
However, certain patterns of floaters and flashes warrant prompt assessment by an eye specialist, ideally within 24 to 48 hours, as they may indicate a retinal tear or detachment:
A sudden onset of new floaters, especially if numerous (a "shower" of floaters)
New or increased flashes of light, particularly in peripheral vision
A dark shadow or curtain appearing in your field of vision, often starting from one side
A sudden decrease in vision
Floaters that appear suddenly after an eye injury or recent eye surgery
These symptoms do not always mean a retinal detachment has occurred, but they cannot be reliably distinguished from a benign PVD without a dilated retinal examination, which is why prompt assessment is recommended.
How Are Floaters and Flashes Assessed?
Assessment typically involves a dilated fundus examination, where eye drops are used to widen the pupil, allowing the retina to be examined carefully for any tears, areas of thinning (such as lattice degeneration), or early signs of detachment. Additional imaging, such as retinal photography or ocular ultrasound (particularly if there is bleeding obscuring the view), may also be used.
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If a retinal tear is found, it can often be treated promptly with laser photocoagulation or cryotherapy, sealing the tear before it progresses to a full retinal detachment. If a retinal detachment has already occurred, surgical treatment is required.
Are Floaters Themselves Treatable?
For most people, floaters caused by a benign PVD do not require treatment. Over time, many people find that floaters become less noticeable as the brain adapts, though they do not typically disappear completely.
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For floaters that are dense, persistent, and significantly affecting vision or quality of life, certain treatment options exist, though these are generally reserved for more severe cases and are discussed individually based on the specific situation, the size and location of the floater, and the balance of risks and benefits.