Phosphenes

What are phosphenes?

You may have experienced this: You have your eyes closed, but you can still somehow see a color or a flash of light.

This is the meaning of phosphenes — flashes of light with or without structure that you see when there isn’t an actual source of light entering into your eye. The most common occurrence of phosphenes results from pressure on the eyeball, but your retina or brain can stimulate them, as well.

Phosphenes are a form of photopsia, a visual phenomenon that includes eye flashers. Like many of these illusions, phosphenes may or may not indicate a medical issue.

You pronounce phosphenes as fah-sfeenz.

What do phosphenes look like?

People often describe phosphenes in terms of light even though there’s no light source. Some people say they’re glittery sparkles. Other people describe them as being like stars. Still, others see geometric shapes.

What are the most common causes of phosphenes?

Many things can cause you to see phosphenes. Sometimes you can see them spontaneously. Possible causes of phosphenes range from rubbing your eyes to neurological diseases or ocular (eye) conditions.

Phosphenes from a blow to the head

You may have heard the expression “seeing stars.” If you hit your head or fall, you may see stars — bright flashes of light even when your eyes are closed. This reaction is similar to what you see when you rub your eyes and see light. Pressure on the eyeball can stimulate the retinal photoreceptor cells, causing the light you see.

Phosphenes from retinal issues

Retinal damage can be a cause for phosphenes. You may see phosphenes if you have:

• Retinal detachment: This serious condition means that the retina has pulled away from its supporting tissue.
• Posterior vitreous detachment: In this condition, the gel that fills the eyeball (vitreous gel) pulls away from the retina.
• Diabetes-related retinopathy: This retinal condition can lead to vision loss.
• Age-related macular degeneration: This eye disease affects central vision and the macula, which is part of the retina.

Phosphenes from neurological conditions

Phosphenes can also occur in certain neurological diseases, including:

• Optic neuritis: With optic neuritis, your optic nerve is inflamed and irritated. This can create pressure against the photoreceptors in your retina. People with optic neuritis may see phosphenes related to their eye movements. Some people who have optic neuritis may go on to develop multiple sclerosis (MS).
• Migraine headaches: Visual symptoms, including phosphenes, often happen with migraines.
• Seizures: Seizures happen because of uncontrolled electrical activity in your brain. Electrical stimulation is also a factor in phosphenes.
• Dementia syndromes and Parkinson’s disease: Phosphenes can occur due to the brain tissue affected in these diseases or with the medications used to treat them.
• Vertebrobasilar insufficiency: With this condition, you have reduced blood flow to the back of your brain. Low blood pressure can also cause visual disturbances when you move quickly, like getting up too fast.
• Traumatic brain injury: You may see phosphenes if you have head trauma.

Phosphenes resulting from radiation therapy and transcranial magnetic stimulation

You may experience phosphenes if you’re having radiation treatment for tumors in your eye, central nervous system or the head and neck area. These flashes of light usually happen during treatment and may persist after treatment as well.

Providers use transcranial magnetic stimulation (TMS) to treat some neurological conditions, such as depression. The electrical activity provoked by TMS can cause phosphenes.

Phosphenes resulting from other causes

You may see phosphenes for other reasons, including:

• Use of prescription and nonprescription medications and/or alcohol.
• Withdrawal from alcohol or medications.
• Rubbing your eyes.
• Coughing.

Some cases of phosphenes don’t appear to have a cause.

What is the treatment for phosphenes?

Providers can’t treat phosphenes, but they may be able to treat the underlying cause of the phosphenes. It depends on what’s causing this visual disturbance to happen. Some cases of phosphenes might not need treatment, such as seeing light when you rub your closed eyes or straining while you cough.

It’s a good idea, though, to contact a healthcare provider if you see phosphenes at other times.

How can phosphenes be prevented?

You may be able to prevent seeing phosphenes by managing other chronic diseases like diabetes, low blood pressure or migraines. Ask your provider for the best ways to do this.

You may be able to prevent head trauma by avoiding certain behaviors like fighting or riding bicycles or motorcycles without a helmet.

When should phosphenes be treated by a healthcare provider?

If you see phosphenes frequently and you have other symptoms that worry you, like double vision (diplopia) or blurry vision, you should consult an eye care provider, such as an ophthalmologist. If you know you have diabetes, or if you’re seeing floaters in conjunction with the phosphenes, you should also consult an eye care provider.

Your eye care provider will begin by asking you questions about your medical history and your symptoms. They’ll then give you a thorough eye examination.

Phosphenes aren’t necessarily dangerous, but they can be a sign of other, more serious problems in some cases.

A note from Cleveland Clinic

Healthcare providers want the best for you. If you’re concerned about symptoms, including those that affect your vision, consult a provider. Finding out about problems early usually leads to improved treatment and prognosis. It’s better to speak to a provider and find out that a symptom is something normal than to ignore the symptom and find out that it’s related to a more serious condition.