You are reading, or looking at a clear sky, or staring at a white wall — and you see them. Small specks, strands, cobwebs, or shadows drifting slowly across your vision. They move when you try to look at them. They are more noticeable in bright light. They have probably been there for a while.

These are floaters, and they are one of the most common reasons people search for an ophthalmologist online. The question that drives almost every search is the same: should I be worried?

The honest answer: usually not. But sometimes, absolutely yes. And knowing the difference could save your sight.

What Floaters Are

The interior of the eye is filled with a clear, gel-like substance called the vitreous. In a young eye, the vitreous is firm and transparent. As we age, it gradually liquefies and shrinks. Small clumps of collagen fibres within the vitreous cast shadows on the retina, and those shadows are what we perceive as floaters.

This process is entirely normal. By the time most people reach their 50s and 60s, they have some degree of vitreous degeneration and a few floaters. These are harmless, annoying, and permanent — though the brain often learns to ignore them over time.

What Flashes Are

Flashes of light — brief, bright arcs or sparkles, usually in the peripheral vision — occur when the vitreous gel physically tugs on the retina. The retina has no pain receptors, but when it is mechanically stimulated, it generates a signal the brain interprets as light. Flashes are common during a posterior vitreous detachment (PVD) — the process by which the vitreous gel separates from the retinal surface.

PVD is a normal age-related event. Most people will experience it at some point, typically after 50. In the majority of cases, the vitreous separates cleanly and without consequence. But not always.

When Floaters and Flashes Become Serious

The danger arises when the vitreous does not separate cleanly from the retina. If the vitreous is firmly adhered to a particular spot, the traction can tear the retina as it pulls away. A retinal tear is a serious event. If left untreated, fluid can seep through the tear and lift the retina off the wall of the eye — a retinal detachment, which is a surgical emergency that can result in permanent vision loss.

The Numbers

Studies suggest that approximately 10% to 15% of patients presenting with a sudden onset of new floaters and flashes will be found to have a retinal tear. Of those with an untreated tear, a significant proportion will progress to retinal detachment. The reassuring news is that a retinal tear, when caught early, can usually be treated in the consulting room with laser or cryotherapy — a quick, effective procedure that seals the tear and prevents detachment. This is why prompt assessment matters so much: a ten-minute laser treatment can prevent a major surgical emergency.

How an Ophthalmologist Assesses Floaters and Flashes

The assessment begins with a thorough dilated fundus examination. Pupil-dilating drops are instilled to allow the ophthalmologist to examine the entire retina, including the far periphery where tears most commonly occur. This examination uses a slit lamp with specialised lenses and may also include indirect ophthalmoscopy with a headset and handheld lens.

In many cases, OCT imaging is used to assess the vitreoretinal interface — the boundary between the vitreous gel and the retinal surface — with micron-level precision. If a tear is found, laser treatment can often be performed immediately during the same visit.

What If Floaters Are Just Floaters?

In the majority of cases, the examination will confirm that the vitreous has separated cleanly, no tear is present, and the floaters are benign. This is welcome news, though it does not make the floaters disappear. Most patients find that floaters become less noticeable over weeks to months as the brain adapts.

For patients whose floaters are severe enough to significantly impair quality of life, a procedure called vitrectomy can be considered. This involves surgically removing the vitreous gel and replacing it with a clear solution. It is effective but carries risks that must be carefully weighed. For most patients, observation and reassurance are the appropriate management.

The Key Takeaway

Long-standing, stable floaters that have been present for months or years are almost always harmless. A sudden change — new floaters appearing abruptly, flashes of light, or any shadow across the vision — is a completely different situation that requires urgent assessment.

The distinction is simple: old floaters are annoying; new floaters are urgent.