Bottom line: A sudden first episode or sudden increase in spots, threads, cobwebs, or “flies” in your vision—especially with flashes like lightning or a camera flash—should not be assumed to be normal aging. Contact an eye service that can perform a same-day dilated retinal examination. A dark curtain or shadow, loss of side vision, or sudden vision loss needs immediate emergency assessment.
Who is this guidance for?
This is for adults who notice new floaters or flashes in one or both eyes. The threshold for urgent assessment is even lower if you have high myopia, a recent eye injury, prior cataract or retinal surgery, a retinal tear or detachment in the other eye, a family history of retinal detachment, diabetic retinopathy, or inflammation inside the eye.
Floaters that have looked the same for months or years are often benign. But a previous diagnosis of ordinary floaters does not cover a new shower of dots, persistent flashes, a shadow, or a change in vision. New symptoms need a new assessment.
Why do floaters and flashes happen?
The vitreous is a clear gel that fills most of the eye. With age it becomes more liquid and may pull away from the retina, a common process called posterior vitreous detachment (PVD). Shadows from clumps in the vitreous can look like floaters. Traction on the retina can create brief flashes, often near the edge of vision.
Most PVDs do not cause lasting harm, but the separating vitreous can sometimes tear the retina or a retinal blood vessel. Fluid can then pass through a tear and lift the retina from the back of the eye. Retinal detachment is often painless, so lack of eye pain does not rule it out.
When should you seek same-day eye care?
Contact an eye care service for a same-day dilated retinal examination if you notice:
- a sudden first floater or a sudden increase in the number or size of floaters;
- repeated or persistent flashes like lightning or a camera flash, often at the edge of one eye;
- a shower of black dots, a new cobweb, or a cloud of dark material;
- new floaters or flashes after an eye or head injury; or
- new symptoms with high myopia, recent eye surgery, or a history of retinal disease.
Seek emergency care now for a dark curtain or shadow, missing side vision, sudden loss of vision, or marked new blur. Severe eye pain, redness, headache, nausea, or vision change after trauma can also signal another urgent eye problem.
Can you tell a harmless floater from a retinal tear at home?
Not reliably. A tear can sit in the far peripheral retina while central vision still seems normal, and early retinal detachment may be painless. A phone camera, home vision chart, or covering and uncovering the eye cannot inspect the peripheral retina.
Eye care professionals check vision and pupil responses, dilate the pupil, and examine the vitreous and peripheral retina. Ultrasound may be needed if blood or clouding blocks the view. Dilating drops can cause glare and blurred near vision for several hours, so plan not to drive yourself home.
How do care pathways differ by country?
The warning signs and need for a dilated retinal examination are the same, but access routes differ. In the United States, this may mean an ophthalmologist, an urgent eye clinic, or an emergency department when urgent eye care is unavailable. In the United Kingdom and some other systems, an emergency optometrist or eye casualty service may assess and refer you. In Korea, same-day ophthalmology is the usual route, with an emergency department for a curtain, field loss, sudden vision loss, trauma, or when timely eye care is not available.
When you call, say “sudden new floaters and flashes” and report any curtain, shadow, or vision loss. Ask specifically whether you need a same-day dilated retinal examination rather than accepting a routine appointment without triage.
Important exceptions and look-alikes
A spreading zigzag or shimmering pattern in both eyes that resolves within about 5 to 60 minutes can occur with migraine aura. Do not label a first visual episode or a change affecting only one eye as migraine without assessment. If visual symptoms come with facial droop, weakness, trouble speaking, or another sudden neurologic symptom, seek emergency help for possible stroke.
Symptoms may fade even when a retinal tear is present. After a normal examination, return promptly if floaters suddenly increase again, flashes become persistent, or a curtain, shadow, or vision loss appears.
What to record and ask at the visit
- Record the exact start time, which eye is affected, how the floaters changed, and whether flashes are recurring.
- Note any curtain, shadow, missing side vision, blur, recent injury or surgery, high myopia, diabetes, or past retinal problem.
- Ask: “Do I need a dilated peripheral retinal exam today?”, “Was there any retinal tear or bleeding?”, and “Which new symptoms mean I should return immediately?”
Related Life Choice Note resources
- Symptom timeline and visit questions
- Medication and supplement list
- Health records and visit preparation
Sources and review date
- National Eye Institute: Floaters
- National Eye Institute: Vitreous Detachment
- National Eye Institute: Retinal Detachment
- MedlinePlus: Retinal Detachment
- NHS: Floaters and Flashes in the Eyes
- Korea Disease Control and Prevention Agency: Floaters
Reviewed October 2, 2026. General health information only, not individual diagnosis or treatment. This page does not claim independent medical review.