Suddenly seeing a flash or flicker in your field of vision can be a disorienting experience. These luminous phenomena, known as phosphenes, sometimes occur with eyes closed, sometimes in broad daylight. Most of the time, they are harmless and transient, but sometimes they can also be a sign of an eye condition requiring medical attention.
How do you know if these light flashes are harmless or if they should raise concern? That's what we will explore in detail in this article.
What is a light flash or phosphene?
A phosphene is a visual impression produced by the retina without external light. Normally, the retina captures ambient light and transforms it into signals transmitted to the brain. But when the retina is stimulated mechanically, chemically, or electrically, it can send a light signal to the brain that was not actually perceived in the environment.
These manifestations take many varied forms: some describe a bright white flash across their vision, others perceive a flicker in the corner of their eye, or even a zigzagging luminous trail that lasts a few seconds. They can appear at night, with eyes closed, or even in broad daylight under certain circumstances.
The main causes of light flashes
The causes of phosphenes are numerous. Some are natural phenomena related to aging or migraines, while others indicate a more serious retinal problem.
1. Vitreous detachment (most frequent cause)
Inside the eye, a gelatinous substance called the vitreous body occupies most of the space. With age, this gel contracts and liquefies. This natural phenomenon, called vitreous detachment, usually occurs after age 40.
When the vitreous detaches from the retina, it can pull on it and cause the sensation of light flashes. This is a very common and generally benign cause of phosphenes. However, in some cases, this traction can lead to a retinal tear, which is more serious.
2. Migraine with aura
Ocular migraines are another common cause. Before the pain, some people experience luminous phenomena called visual auras. These visual symptoms last an average of 20 to 30 minutes and disappear on their own.
These auras can take the form of:
- luminous zigzags,
- colored flickers,
- blurred or blinding areas in the visual field. Sometimes they occur without a headache: this is called a visual migraine.
3. Blood pressure and stress
Variations in blood pressure, whether related to hypertension or hypotension, can disrupt blood circulation in the eye and cause light flashes.
Stress, by increasing blood pressure, can also promote the appearance of these luminous phenomena. This explains why some people experience them after an intense day or during significant physical exertion.
4. Eye trauma and surgery
A direct blow to the eye or recent surgery (for example, cataract surgery) can temporarily cause light flashes. In these cases, the phenomenon is often transient, but it is always recommended to report it to your optometrist or ophthalmologist.
5. More serious complications: retinal tear and detachment
In rarer cases, light flashes are a sign of a retinal problem.
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Retinal tear: when the vitreous body pulls too hard, it can create a tear in the retina. If left untreated, this tear can progress to retinal detachment.
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Retinal detachment: this is a medical emergency. It manifests as a partial loss of vision, as if a black curtain were obscuring part of the visual field. Without rapid treatment, it can lead to irreversible vision loss.
Which symptoms should raise concern?
It is normal to sometimes see a small isolated flash, especially with age. But some signs should attract attention. If light flashes appear suddenly and repeatedly, if they are accompanied by floaters (these small mobile black dots that cross vision), or if a part of the visual field darkens as if a curtain were falling in front of the eye, it is imperative to consult quickly.
These symptoms do not always mean there is a serious problem, but they can be a sign of retinal damage. In this case, an examination of the fundus by an ophthalmologist will determine the exact cause and, if necessary, intervene without delay.
Is there a treatment for phosphenes?
Light flashes themselves do not have a specific treatment, as they are not a disease but a symptom. Management is based on the underlying cause.
When they are related to a migraine, treatment mainly aims to relieve pain and identify triggers to prevent attacks. In cases of hypertension, medical follow-up and sometimes a lifestyle adjustment are necessary. If the retina has a tear, laser treatment can be performed to consolidate the fragile area and prevent worsening. And if retinal detachment is confirmed, emergency surgery is necessary to preserve vision.
How to protect your visual health?
It is not always possible to prevent phosphenes, but certain habits contribute to maintaining good eye health. Regular check-ups with an optometrist, especially after age 40, allow for early detection of any anomalies and ensure that vision remains optimal every day. Getting a comprehensive eye exam also helps to check if a prescription update is necessary and to adjust your frames or corrective lenses accordingly.
Stress management and blood pressure also play an important role, as does a balanced diet rich in nutrients beneficial for the eyes (fatty fish, green vegetables, red fruits). Finally, protecting your eyes during risky activities, DIY, contact sports, sun exposure remains an essential precaution.
FAQ - Light flashes in the eyes
Is it normal to see light flashes at night or in the dark?
Yes, it can happen, especially when the vitreous body slightly pulls on the retina. If the phenomenon repeats often or is accompanied by vision loss, it is recommended to consult.
Are light flashes dangerous?
Most of the time, they are benign, for example, related to eye aging or a migraine. However, they can also indicate a retinal tear or detachment, which require rapid medical attention.
Why do I see light flashes in only one eye?
When only one eye is affected, it is possible that the cause is related to the vitreous or retina of that particular eye. This warrants medical evaluation to rule out any serious problem.
Can phosphenes be linked to fatigue or stress?
Yes. Significant eye fatigue, prolonged stress, or blood pressure variations can accentuate these luminous phenomena, especially in people already prone to migraines.
Is it normal to see light flashes after cataract surgery?
Yes, it is not uncommon to observe transient light flashes after eye surgery. But if the symptoms persist or intensify, follow-up is necessary.
When should you consult urgently?
If you notice a black or dark curtain in your vision, a partial loss of vision, or the sudden appearance of numerous floaters accompanied by light flashes, this is an ophthalmological emergency.
