The retina is a thin, light-sensitive tissue that lines the back of the inside of your eye. It perceives focused light that enters your eye and transmits electrical signals to your brain via the optic nerve, allowing your brain to convert this information into a picture.

The vitreous humor is a clear jelly-like fluid that fills up a large part of your eyeball. It protects the retina and helps your eye maintain its shape.

The retina knows only one “language,” and that’s light. This means that when anything stimulates the retina, such as a push or pull, it can trigger a light impulse — even in a totally darkened room.

For example, tiny fibers float in the clear vitreous fluid, and some are attached to the retina’s surface. These fibers may tug or pull on the retina’s surface, causing flashes or light sparks from the friction.

Flashes of light in the eye are not a condition on their own. Instead, they tend to be a symptom of another condition.

Some causes may be directly related to your eye health, while some result from health conditions that affect other body organs and systems.

Several types of eye conditions may cause light flashes in the corner of your eye or in your field of vision, including:

• Posterior vitreous detachment: This is one of the most common causes of light flashes in your eye. It typically happens as you get older. With posterior vitreous detachment, the vitreous humor detaches from the retina. If it happens too quickly, it can cause small flashes of light, usually in the corner of your vision. It can also cause floaters. This condition usually doesn’t require treatment, but visit an eye doctor to have it checked.
• Retinal tear: A retinal tear is when there is a break or rip in your retina. It often happens due to posterior vitreous detachment. It can sometimes worsen and turn into a retinal detachment.
• Retinal detachment: Retinal detachment is a serious condition that can cause partial or complete vision loss. It is when the retina detaches, shifts, or moves away from the back wall of the eye. It can result from posterior vitreous detachment or from fluid leaking from blood vessels that builds up behind the retina — a condition called exudative retinal detachment. Both retinal tears and retinal detachment are medical emergencies that require urgent eye care.
• Optic neuritis: Optic neuritis happens when the optic nerve becomes inflamed. This can be caused by an infection or a nerve-related disorder such as multiple sclerosis. With optic neuritis, symptoms like pain and flashes of light often get triggered by eye movement.
• Pressure on the retina: If you rub your eyes, cough too hard, or get hit on the head, you may notice light flashes due to extra pressure.
• Injury: An injury directly to your eye may cause you to see flashes or “stars” due to pressure on the retina.

Light flashes may also be a symptom of:

• Occipital epilepsy: This rare type of seizure in the occipital lobe of the brain can cause visual flashes in the eye. It can be a sign of seizure activity. This is sometimes mistakenly diagnosed as a migraine aura. Typically, though, occipital epilepsy seizures are shorter (seconds) than migraine aura (minutes).
• Migraine: Visual disturbances are common with a migraine aura. You may see flashes of light, zigzag lines, stars, or dots of light in your eyes. These symptoms usually go away within 60 minutes.
• Transient ischemic attacks (TIAs): Commonly referred to as ministrokes, TIAs happen when a blood clot temporarily restricts blood flow to your brain. TIAs can cause visual disturbances, including flashes of light in your eyes.
• Diabetes: Flashes of light or floaters can be a symptom of diabetic retinopathy.
• Tumors: Tumors in different areas of the eyes or brain can generate flashes when you move your head or neck.

Some medications may cause light flashes or floaters in your eyes. In many cases, this is due to the medication being administered intravitreally — with an injection into your eye — rather than due to the medication itself.

Medications linked to light flashes include:

Only a doctor can confirm the cause of your symptoms, so it’s important to get medical help for any new, sudden, or severe vision symptoms.

Some of the conditions that can cause light flashes in your eye are medical emergencies and require immediate medical care, such as:

• retinal tears and retinal detachment
• vision symptoms if you have diabetic retinopathy
• optic neuritis
• eye or head injury
• TIA

If you have any of the following symptoms, get medical care immediately:

• sudden flashes of light, especially when you look to the side
• partial vision loss or darkened vision
• blurred vision
• dizziness
• other sudden vision-related problems
• a seizure that lasts longer than usual for you, or your first ever seizure
• if you get migraine auras, migraine aura that lasts longer than 1 hour or is different from usual
• vision symptoms alongside any other symptoms, such as confusion or a severe headache
• symptoms of a TIA or stroke

A TIA can often be a warning sign of a stroke. That’s why it’s important not to ignore the signs. If you notice any of the following symptoms, get medical attention as soon as possible:

• weakness or numbness on one side of your body
• slurred speech or difficulty talking or understanding others
• visual disturbances or visual changes
• dizziness
• severe headache

Any serious injury to your eye also needs immediate medical attention.

Flashes of light in your eye are typically a symptom of an issue related to an underlying eye problem or some other health condition. A comprehensive eye exam, including pupil dilation and retinal funduscopy, can help identify the reason for the flashes. The treatment will depend on the underlying cause.

When you consult a healthcare professional, be sure to let them know about all the over-the-counter and prescription medications you use. Some medications can cause vision-related side effects.

In some cases, as with optic neuritis, treating the cause of the inflammation or infection can stop the light flashes. Tears in the retina or retinal detachment may require surgery.

There’s no treatment for shrinking of the vitreous that occurs due to age, unless it starts to cause retinal damage like a retinal tear.

A wide variety of issues can cause flashes of light. Some may be related to your eye, and some may be a symptom of another type of condition, such as migraine, epilepsy, diabetes, or TIAs.

To stay on top of your eye health, it’s important to visit an eye doctor for a checkup at least once a year.

Regular eye exams can help your healthcare professional determine if there have been any changes to your vision or the health of your eyes.