Flashes and Floaters: When They're Normal and When They're an Emergency

Quick answer: Floaters you've had for years that drift slowly are usually harmless. Call a retina specialist the same day if you notice a sudden shower of new floaters, flashes of light (especially in your side vision), a shadow or curtain over part of your vision, or a sudden drop in vision. These can signal a retinal tear or detachment. Caught early, a tear can often be sealed with an in-office laser before it becomes a detachment that needs surgery.

What are floaters?

The inside of your eye is filled with a clear gel called the vitreous. With age, the gel becomes more liquid and forms clumps and strands. Those clumps cast shadows on the retina, and you see them as specks, threads, cobwebs, or rings that drift when your eye moves. They're most noticeable against a bright sky or a white wall.

What causes flashes?

Flashes happen when something tugs on the retina. The retina responds to physical stimulation by sending a light signal, so you see brief arcs or sparks of light, often in your peripheral vision and more noticeable in dim light.

Flashes are a sign the vitreous gel is pulling on the retina.

Why do new floaters and flashes happen together?

Most often, it's a posterior vitreous detachment (PVD). As the vitreous shrinks with age, it peels away from the retina. That's a normal part of aging, and most people experience it by their 60s or 70s.

Usually the gel separates cleanly. Sometimes it pulls hard enough to tear the retina. Research shows roughly 1 in 7 people with a symptomatic PVD has a retinal tear at the time of the exam. That's why a new PVD deserves a dilated exam. Read more in Posterior Vitreous Detachment.

When are floaters an emergency?

Why does timing matter so much?

A retinal tear lets fluid seep under the retina and lift it off the back of the eye. That's a retinal detachment, and it can cause permanent vision loss if not repaired.

• A tear can often be treated in the office with laser or freezing treatment (cryotherapy) that creates a seal around it. The visit is short and recovery is quick.
• A detachment usually needs surgery, such as pneumatic retinopexy, scleral buckle, or vitrectomy. The outcome depends heavily on whether the central retina (macula) has detached.

The difference between a quick laser treatment and surgery is often a matter of days. Learn more in Retinal Detachment: Symptoms and Surgery Options.

Who is at higher risk of a retinal tear?

• People who are very nearsighted
• People who have had cataract surgery
• Anyone with a prior retinal tear or detachment in either eye
• People with a family history of retinal detachment
• Anyone who has had an eye injury

What happens at the exam?

Dr. Garg dilates your eyes and examines the entire retina, including the far edges where tears usually happen. She may use gentle pressure on the eyelid to see the periphery and take OCT or ultrasound images. If she finds a tear, treatment is often the same day.

Can floaters be treated?

Most floaters become less noticeable over weeks to months as the brain learns to ignore them and the gel settles. For rare cases where large floaters seriously affect vision long term, vitrectomy may be discussed. The first priority is making sure your retina is healthy.