Flashes in vision can be caused by migraine aura or by the gel inside the eye tugging on the retina. Sudden new flashes or floaters need an urgent eye exam.
Causes
- Posterior vitreous detachment (PVD): the gel inside the eye tugs on the retina. Common after age 50.
- Migraine aura: zigzag shimmering lights.
- Retinal tear or detachment.
- Eye injury.
Warning
New flashes, many new floaters or a dark curtain over vision can mean a retinal tear.
Emergency
See an eye doctor the same day.
Migraine aura
Lasts 20 to 30 minutes.
Mechanisms
Flashes of light occur when the vitreous gel inside the eye tugs on the retina, which sends signals the brain sees as flashes. The gel shrinks with age, and posterior vitreous detachment affects about 25 percent of people by age 50, and 65 percent by age 65. It is usually harmless, but it can lead to a retinal tear.
- A shower of new floaters with flashes and a dark curtain or shadow in vision suggests a retinal tear or detachment, an emergency.
- Retinal detachment occurs in about 1 in 10,000 people per year.
- Ocular migraine or migraine aura brings zigzag shimmering patterns lasting 10 to 30 minutes, often in both eyes.
What to do
Get a dilated eye exam within 24 to 48 hours of new flashes, and emergency care if you have vision loss or a curtain effect. Retinal tears are treated with laser or freezing therapy, and detachments need surgery. Other causes include eye injury, inflammation and, rarely, stroke or optic nerve issues. Sudden flashes with weakness or speech problems need emergency care.
Mechanisms
Flashes of light in vision occur when the vitreous gel tugs on the retina, common with aging as the vitreous separates. Migraine aura produces zigzag shimmering lights that last 20 to 30 minutes. Other causes include retinal tears and detachment.
What to do
Sudden new flashes, floaters or a curtain over vision are an eye emergency requiring same day exam. Retinal detachment affects about 1 in 10,000 people per year.
Vitreous and retina causes
The vitreous gel liquefies with age, and by age 80, about 60 percent of people have posterior vitreous detachment. Flashes occur when the gel tugs on the retina. A retinal tear occurs in about 10 to 15 percent of symptomatic PVD patients. Migraine aura causes jagged lines lasting 20 minutes without headache sometimes.
Urgent steps
New flashes with floaters, a shadow or curtain across vision requires a dilated eye exam within 24 hours. Treatments for tears include laser or freezing, and detachment needs surgery. Risk factors include nearsightedness, eye injury, previous cataract surgery and family history. Flashes after head trauma are also a reason to seek care.
Based on data from the American Academy of Ophthalmology
