Why You Might Be Seeing Stars

Seeing stars can be unsettling. Most of the time, it is nothing to worry about. But, in some cases, it may mean there is something wrong with your vision or eye health.

This phenomenon is known as photopsia.

Symptoms of photopsia include seeing:

• Bands of light
• Colorful rings
• Flashing lights
• Sparks
• Stars

These visual disturbances are usually due to temporary physical pressure on the eyes—for example, rubbing your eyes or a hard sneeze.

However, it can also be a symptom of a medical issue, such as migraine headaches or a problem with the health or structure of the eye.

If you experience photopsia often or for extended periods of time, see your healthcare provider. An optometrist or opthalmologist can give you a full eye exam to help determine the cause.

This article discusses photopsia and five possible medical causes for seeing stars.

How Photopsia Occurs

When the retina (the lining in the back of the eye) senses light, it sends a message to the optic nerve. The optic nerve relays the message to the brain, which then identifies the image.

When you have photopsia, something other than visible light stimulates the retina. These false flashes of light are known as phosphenes.

Phosphenes can be triggered by pressing the eyes. They can also happen when neurons in the eye or the brain are stimulated.

The most common cause of phosphenes is pressure on the eye. This can include rubbing the eyes, sneezing, or receiving a blow to the head.

Flashes of light can also occur due to a medical condition like:

• Low blood pressure
• Eye injury
• Diseases of the eye or brain
• Migraines

Pressure

Phosphenes can be caused by pressure inside the eye or brain. These phosphenes can last for a few seconds. For example, you might see stars when you rub your eyes, sneeze, cough, strain, or vomit.

When phosphenes last longer than a few seconds or happen often, it could be a sign of a more serious issue. You should see your eye doctor right away.

Possible reasons include:

• A blood vessel problem
• Infection
• Inflammation
• Injury
• Thyroid disease
• Tumor

Posterior Vitreous Detachment

Posterior vitreous detachment (PVD) is a common condition caused by aging.

The vitreous is a jelly-like filler inside the eyeball. It keeps the eyeball plump and round. The vitreous is attached to the retina. With normal aging, the vitreous becomes less firm. It can start to shrink and tug on the retina.

If the pulling becomes strong enough, the vitreous may separate from the retina. When this occurs, it can cause a person to see floaters, flashes of light, or stars. Photopsia caused by PVD can look like streaks of light, usually at the side of the field of vision, also known as peripheral vision.

PVD can cause damage to the retina. It's important to tell an eye doctor about any PVD symptoms you experience, even though it is a normal part of aging. Your healthcare provider can monitor you for signs of a problem in the first few weeks of a PVD.

Retinal Disorders

Problems with the retina can cause you to see stars, flashes, or bands of light. A retinal detachment is one such condition. It occurs when the retina pulls away from its normal position in the eye.

Symptoms include:

• Flashes of light in one or both eyes
• A dark shadow that seems like a curtain covering part of your view
• An increase in floaters, which are small dark spots or squiggly lines that float across your field of vision

Symptoms of a detached retina come on quickly. If you notice these symptoms, see an eye doctor or go to the emergency room.

If a detached retina is not treated promptly, it can lead to more damage. A delay in treatment raises the risk of permanent vision loss or blindness. 

Other retinal conditions can lead to vision loss and cause you to see stars. These include:

• Diabetic retinopathy
• Macular degeneration
• Optic neuritis
• Retinitis pigmentosa

Some medications also can affect how the retina works in ways that produce phosphenes. One such drug is Corlanor (ivabradine), which is used to treat tachycardia (rapid heart rate).

Migraines

Visual changes known as auras are a common symptom of migraine headaches. An aura typically lasts about 20 to 30 minutes and then goes away on its own, without any treatment.

With some migraines, a visual aura may occur without pain. These are called ocular migraines. The aura can affect one or both eyes. You might see:

• Rainbow-like colors
• Flashes of light
• Stars
• Zig-zag lines
• Blind spots

If a headache follows the flashes, the episode is diagnosed as a migraine headache. If they occur without pain, it is often called as a migraine without a headache.

Brain-Related Causes

While less common, phosphenes can occur due to a problem in the areas of the brain that handle vision. This may occur because blood isn't flowing properly. It can also happen because of brain damage.

Cerebrovascular disease (blood vessel disease in the brain) or systemic low blood pressure can result in less blood supply to the brain. The brain may not function as well without enough blood supply.

Postural hypotension is a sudden drop in blood pressure. This can happen when someone who already has high or low blood pressure lies down or stands up too fast.

This drop in blood supply can trigger flashing lights or similar phenomena for a few seconds.

Summary

Seeing stars is known as photopsia. The individual flashes of light are called phosphenes.

They often occur when pressure on the eye stimulates the retina. The retina is a light-sensing part of the eye. Pressure can be caused by an outside force, such as rubbing your eyes, or internal structural problems or inflammation.

Photopsia can also occur with migraines, changes in blood pressure or blood flow to the brain, or brain damage.

Photopsia is usually harmless. However, if you see them often, tell your healthcare provider or eye doctor. If you have other symptoms like a shadow or curtain in your vision or an increase in floaters, get emergency help right away.