You’ve heard the saying, “seeing stars.” Sure, probably in context of getting hit in the head. There are actually many reasons that you can see stars. All of them should be taken seriously. However, many people don’t realize that there is a reason for seeing those flashes of light or even “floaters” in their vision.

How Does Seeing Stars Work?

Seeing stars is usually the result of a disturbance either in the retina or in the brain. It is much more likely that the problem is related the retina. This thin lining of cells in the back of the eye sends messages to the brain when light is detected. It does not “see” things like colors or shapes, it simply perceives light and transmits a signal. These signals are then interpreted in the brain to give us visual images that we know as sight. In front of the retina, a special gel called the vitreous is in place to protect it. If the retina itself gets inflamed or if the vitreous gel moves or shrinks, the retina inappropriately sends signals to the brain. Even if no external light signal exists, the brain does not know the difference and “sees” a flash of light.

Seeing stars can also be caused by a problem in the brain itself separate from the retina. For example, if something disrupts the electrical activity in the brain, it may also send false signals that result in flashes of light.

What Causes You To See Stars?

There are many reasons that a person might see stars. Unlike the common misperception of only seeing stars after a hit to the head, things like migraines and retinal detachment can also cause the problem. Here are a few of the most common causes:

A blow to the head

There’s a reason that seeing stars is so closely associated with being hit in the head. It has been a staple in cartoons for many years, possibly leading to the connection. However, there is a more realistic reason for the phenomenon. The back of the brain, or the occipital region, is the part that processes visual information. Normally, a layer of fluid prevents the brain from bouncing against the skull. However, after a blow to the head, the occipital region can hit the skull, causing the brain to send out light signals that are perceived as flashes.


Migraine headaches are notorious for altering vision. They can cause flashes, spots, waves, tunnel vision, or lines. These visual changes often occur before a headache and are part of a sensation known as an aura. Occasionally, a person can have a retinal migraine, a rare condition that affects vision in only one eye. Other migraine symptoms include throbbing and severe headache, photosensitivity, nausea, and dizziness.

Vitreous gel movement

We briefly mentioned that movements of the vitreous gel can cause flashes to appear. When this happens, the vitreous pulls on the retina and can trigger it to send signals even if there is no light. This can be a serious issue if the flashes are happening frequently, come on suddenly, or are accompanied by other changes like floaters or cloudiness.

Retinal detachment

Sometimes the vitreous gel can pull so hard that the retina is torn away from the back of the eye. If this happens, a person will see stars or flashes, have a loss of vision, and will have a curtain or shadow across the sight that remains. Risk factors for retinal detachment include: being over 40, a family history of the problem, a previous retinal detachment, and being very nearsighted.

What Is The Difference Between Flashes And Floaters?

We’ve talked quite a bit about what can cause flashes of light in your vision and what causes them. Many times, they can be accompanied by another visual disturbance known as floaters. Unlike a flash of light, these look like a shadow, line, or clump that move slowly across your vision. They can be caused by chunks of protein or cells in the vitreous that float around in the fluid, hence the name floaters. Bursting of tiny blood vessels in the eye can also be to blame. Although they are typically harmless—and can happen normally as we age—if floaters appear suddenly or occur frequently, you may want to consult your eye doctor.

When To See A Doctor

If you’re experiencing stars, flashes, or floaters, it is probably a good idea to visit your eye doctor. Even though these symptoms are painless and may not cause severe problems with your eyesight, they can be a sign of a serious problem. However, if you only see them occasionally you may not have to get them checked out. You should visit the eye doctor if:

You see more flashes or floaters than usual

  • You have a sudden onset of new flashes
  • You have both flashes and floaters in the same eye
  • You have darkness in your eyesight or have noticed an immediate change

What To Expect When Seeing The Doctor

A trip to the eye doctor for problems with floaters or flashes will include a few tests to help determine the exact cause. For non-impact trauma flashes, the doctor will perform a thorough exam. Your pupils will be dilated. If identifying the problem is difficult, an ultrasound of your eye can also be helpful. For anyone with occasional floaters or flashes, you likely don’t need to schedule a special appointment. However, you should mention it to your eye doctor at your next regularly scheduled appointment. If you are concerned though, making a special visit certainly won’t hurt. Sometimes it is better to be safe than sorry when dealing with seeing stars or floaters.