Floaters and flashes

What they are

The vitreous is a clear gel filling the eye. With age it liquefies and shrinks, casting shadows on the retina perceived as floaters. When it pulls on the retina you may see brief flashes, especially in dim light or when moving the eye.

Posterior vitreous detachment (PVD)

PVD is when the gel separates from the retina — very common after age 50. It causes a sudden increase in floaters, often a large ring or cobweb, and intermittent flashes. Most PVDs are benign, but the pull can occasionally cause a retinal tear at the same time, which is why new symptoms need a dilated eye check.

Emergency warning signs

Same-day assessment if you notice:

• A sudden shower of new floaters
• Repeated flashes that are new or increasing
• A dark shadow or curtain spreading from the side
• Sudden blur or loss of vision in one eye
• Floaters after eye injury or surgery

Retinal tear and detachment

A retinal tear can let fluid under the retina, causing detachment — a sight-threatening emergency. Laser or cryotherapy can seal tears before detachment spreads. Detached retina usually needs surgery (vitrectomy or scleral buckle). Earlier treatment preserves more vision.

Monitoring and treatment

Stable long-standing floaters that have not changed for months or years usually need no treatment. Bothering floaters in an otherwise healthy eye may rarely be treated with vitrectomy after careful counselling. The priority is excluding tear or detachment when symptoms are new.

When to seek care

Treat any sudden change as urgent until an eye specialist examines the retina. Routine optometry visits are not enough for new flashes — you need a same-day or next-day dilated fundus check. Do not drive if vision is significantly reduced.