Unless you're watching fireworks on the 4th of July, you don't expect to see lights streaking across your visual field. But flashing lights can be caused by several different medical conditions, including retinal detachment, shrinking vitreous humor, eye hemorrhage, stroke, or migraine. (Learn more)

Some flashes are best ignored. But if they're new, intense, or very disturbing, they could be a sign of a serious illness your doctor should treat. (Learn more) Once you arrive, you'll need a thorough eye exam, and you might need surgery to preserve your vision.

Some conditions that cause flashing lights can't be prevented. But there are steps you can take at home to monitor your vision and protect your eyes, so you'll be ready if the flashing starts. (Learn more)

photophobia

What Could Cause It?

When your eyes are healthy and working well, the only flashes you see come from outside your body. When you see them in your visual field but others can't see them, you could be dealing with an eye illness or another health problem.

Flashes in your eyes are often caused by:

  • Retinal detachment. A small slice of tissue in the back of your eye transforms light into images. The retina needs a steady flow of blood to work right, and when that's interrupted through a tear, your information flow breaks down. Your brain interprets the break as a flash of light. This is a medical emergency, says Mayo Clinic, as the longer the tear remains, the more likely it is that you'll have permanent vision loss.
  • Shrinkage of vitreous humor. A thick, gel-like substance keeps your retina in place. As you age, that material gets smaller and smaller. Sometimes, it tugs on the retina, and that can lead to flashes and sparks. This is a common problem, says Harvard Medical School, as about a quarter of people have shrinkage by age 60. But in about one person in six, the reduction leads to retinal detachment.
  • Hemorrhage. Blood nourishes every cell in your body, and in your eyes, it's delivered by tiny little vessels that line the eye socket. If one of those capillaries breaks, blood can leak into the space behind your retina, and that can lead to retinal detachment and flashes of light.
  • Stroke. Bleeding inside the brain can also cause flashes of light. Other stroke symptoms include numbness, weakness, slurred speech, or headache. This is a medical emergency.
  • Migraines. Some people develop an aura before the pain of a migraine hits. Unusual electrical activity in the brain leads to all sorts of shifts in perception, including flashes of light. If they last for 10 to 20 minutes and are followed by pain, the light is probably sparked by a migraine, says the Canadian Ophthalmological Society.

When Should You See a Doctor?

No one wants to visit a clinic when it's not absolutely necessary. Sometimes, the flashes you see fade away in a second or two and don't return, and those may not require urgent care. But some optical changes indicate that something is very wrong with your eyes, and when those symptoms appear, quick care is crucial.

You should see a doctor for flashes, says the American Academy of Ophthalmology, if:

  • The light is accompanied by cloudiness or dark blobs blocking your view.
  • You see flashes when you've never seen them before.
  • The flashes get suddenly stronger or brighter, and they won't go away.
  • A dark cloud (sometimes described as a curtain) slides across your field of vision.

You should also see a doctor if the flashes are accompanied by numbness or an inability to talk. Severe pain in your eyes, especially after you've been hit in the head, should also prompt quick medical care.

The treatment you'll need depends on the issue causing your flashes. If you have a stroke, for example, your doctors will work to remove the blood clot and restore blood flow. If you have a migraine, doctors might use medications to soothe the electrical firestorm in your mind.

But if the flashes are caused by retinal detachment or some other retinal issue, you'll need eye surgery. Per Australian Family Physician, doctors can perform a vitrectomy to remove the gel inside your eye (which can fix bleeding tissues), to push the retina back into place, and to hold it there as it heals. Every surgery is a little different, and the care you need might be different than the care someone else needs. But these are all considered specialty procedures, so you'll need an eye expert to help you.

How Can You Protect Your Eyes?

Smiling mature patient consulting with optometrist for an eye checkup

Annual eye exams can help your doctor spot changes in your vision before they cause significant problems. Your doctor can dilate your pupils to allow for examination of the back of the eye, and they can check eye pressure to make certain glaucoma isn't developing. Keeping these appointments is one of the best ways to protect your eyes.

You can also check your vision at home between visits. The organization Fighting Blindness recommends that you do the following:

  • Cover one eye.
  • Look straight ahead, and check your vision.
  • Look to the side, and check your vision.
  • Note the placement and presence of floaters and flashes.
  • Check the other eye.

Bring your notes with you to your appointment, and talk with your doctor about anything unusual you've seen.

Never be afraid to talk with your doctor about your symptoms and your concerns. Your doctor's job is to keep you healthy, and open communication can help make that happen.  

References

Retinal Detachment. (March 2019). Mayo Clinic.

What You Can Do About Floaters and Flashes in the Eye. (October 2018). Harvard Medical School.

Flashes and Floaters in Your Eyes: When to See the Doctor. (March 2019). Cleveland Clinic.

Floaters and Flashing Lights. Canadian Ophthalmological Society.

Flashes of Light. (January 2019). American Academy of Ophthalmology.

Flashes and Floaters: A Practical Approach to Assessment and Management. (April 2014). Australian Family Physician.  

Flashes and Floaters. Fighting Blindness.