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Causes of Sudden Onset Of An Arc Of Flashing Light On The Periphery Of One Eye & Its Prevention

Of all the organs we have, our eyes have a special role to play, as it gives us the ability to perceive vision. However, eye disorders can affect a person to a great extent. A common question that we come across is, what does a sudden onset of an arc of flashing light on the periphery of one eye indicate? Let us understand this in detail.

Floaters are a common name used for describing threads, spreads, and cob-web like images that are sometimes seen in the line of sight of a person. Flashes are flickering strands of light that occur in the visual field and are usually supported by floaters. Both of these disorders are regarded as harmless but may pose danger when they occur suddenly.

What Does a Sudden Onset of an Arc of Flashing Light on the Periphery of One Eye Indicate?

The eye is made of a thick, clear jelly known as vitreous humor. With age, the vitreous humor dries up losing some water content and it shrinks as it allows the retina to become disconnected, creating a pulling motion known as vitreous humor. The tugging results in the tearing of the retina and can cause detachment. This is usually known as Posterior vitreous detachment (PVD). Untreated PVD can lead to retinal detachment (RD). The retina can cause one to go blind as it is described as a thin lining of sensitive cells at the back of the eye and its pull away from the blood vessels making a scarcity of oxygen can make one devoid of eyesight. Studies suggest that retinal detachment is often a preventable cause of vision loss.1 Hence, it is necessary to know about it, the early symptoms and warning signs to seek timely medical treatment.Sudden Onset Of An Arc Of Flashing Light On The Periphery Of One Eye

What does a sudden onset of an arc of flashing light on the periphery of one eye indicate? A very common reason for the sudden occurrence of an arc of flashing light in one eye is the change that occurs in the vitreous humor. It is jelly-like hyaluronan used to fill the back of an eye. As a person gets older this solid jelly-like substance loses its form and turns into a runny jelly-like substance, it loosens the attachment of the retina from its back surface. The process by which vitreous detaches from the retina is called the separation or vitreous detachment. Considered vitreous or debris, the floating inflammatory cell or other rarer things can float are called floaters. These result in spots, circle, half-moon, dots, cobwebs or films in eyes. They stay bothersome mainly for the first few months and after that either they disappear or our brain adapts to it and makes it seem non-existent. Over time people become accustomed to the floaters and are not bothered by them at all. For very few extreme cases they might be visible and cause hindrance in the line of sight while reading or driving and may need to be removed surgically.

In some rare cases where the vitreous pulls itself away from the retina, it might cause tearing in the retina. This results in symptoms, which include bright flashes of light or floaters, which are usually defined as a black ribbon. The tearing of retina is a serious medical condition and needs to be addressed before the retina gets fully disconnected. If the retina gets disconnected then a part of the vision gets obscured and a curtain-like shape becomes visible from the periphery of the eye to the center. This is an emergency medical situation and the person should be taken immediately to an ophthalmologist.

In retinal detachment, tiny arc-like temporary flashes are common in the peripheral vision. This is perceived because the vitreous puts a strain on the retina, which to the person appears as like it is a flash of light. These flashes remain persistent throughout the time till the vitreous gets separated from the retina. Rare flashes perceived by a person are also associated with the tearing of retina. Another reason for the flashes is ocular migraine, or sometimes also known as optical migraine. These migraines are more common to persons as they age, although they also occur in young persons. The transition of the severe vascular headaches to visual phenomenon over time is fairly common in this disorder.

However, some people who experience frequent headaches and migraines might also develop these visual phenomena. These can vary to include symptoms like heat waves, blurry vision, bolt-shaped lightning. Sometimes, this is visible in the form of a crescent shape that moves from the center to the side boundaries. These symptoms may last for some minutes to some hours. This is caused due to the vascular spasm in the brain’s visual part. These are not permanent problems and a person suffering from this disorder can wait for it to pass away. However, in case of severe or frequent headaches, the patient should consider visiting a neurologist.

Causes of Sudden Onset of an Arc of Flashing Light on the Periphery of an Eye

As the cause of sudden onset of an arc of flashing light on the periphery of one eye indicates possibility of retinal detachment, let us look at the causes in detail.

The causes of this detachment are mainly due to:

Old age: when the retina become thinner and more brittle.2

Injury or harm caused: a direct injury can cause the detachment of the retina.

Occasional flashes of lights are normal when one rubs the eyes or get even the slightest of injury as the vitreous gel inside the eyes shrinks pulling the retina. However, an increase in the flashlights (photopsia) along with cloudiness and “curtain” images requires attention. One should visit an ophthalmologist for symptoms like distorted visions or floating black spots or rings on the field of vision. Sometimes there are shadowy visions or visions of a black curtain, halos around light or starbursts around the light. There are chances of sudden vision loss even and it can be permanent blindness. Migraine too is also one of the reasons to see distorted visions.

PVD (Posterior Vitreous Detachment): This vitreous is a gel-like fluid that fills the total back part of the eye. The retina is attached to the vitreous by tiny fiber-like substance. As a person ages, these fibers shrink and detach the vitreous from the retina partially or completely. This shrinking pulls the retina and stimulates the nerves present in the area to produce an effect, which is perceived as flashing of light. This situation occurs to persons who are nearing their sixties and are highly seen in nearsighted people.

Harmless Flashes: Harmless flashes are also seen in healthy individuals. If you rub your eyes, you can experience colors, shapes or even sparkle of light. This occurs basically due to the pressure that you put when rubbing the eyes, putting pressure to the optic nerve and areas of eyes, which perceives vision.

There may be other causes of detachment or sudden onset of an arc of flashing light on the periphery of one eye. Other possible causes include head trauma, lowering of blood pressure, lowered levels in blood sugar, mini-stroke, macular degeneration, eye or brain tumor, or inflammation in the eye nerves.

When to Consult a Doctor?

If the situation worsens or is associated with any other complaint, it is best to see a doctor. Sometimes the tugging can cause bleeding in the vitreous section. The detachment can be fixed by a simple surgery with the removal of vitreous gel and replacing it with a saline solution which is known as vitrectomy which leads to no further vision loss. Another process is using a laser treatment to break down the dense vitreous condensation. Though, sometimes reduced periphery or central vision is experienced by some people even after successful surgery. A vitreous detachment is common for people of 50-80 years of age though it is also possible to happen in nearsighted people. If the vitreous detachment is in one eye it is likely to happen in the other sooner or later.

Seeing an ophthalmologist can help to detect the problem in time and plan appropriate treatment. It shouldn’t be left unattended as it can lead to permanent blindness when it can be cured when treated on time. There is no specific treatment for the separation of retinal from vitreous gel but surgery or laser can be recommended by the doctor for the broken and torn retina.

Precautions to Prevent Sudden Onset of an Arc of Flashing Light on the Periphery of an Eye

Sudden onset of an arc of Flashing light on the periphery of an eye can be seen in many medical conditions. Some of these can be medical emergencies too, hence knowing about these is important. For people with medical concerns like diabetes, high blood pressure or those under medications should keep a check on their health, with regular follow-ups.

Protecting the eyes and preventing them from any problems is necessary. It is always a good practice to visit an ophthalmologist time to time for a regular checkup of the eye’s health. Report any eye related medical concerns or vision problems to the doctor and get timely treatment. When sudden flashing is observed then it is advised to immediately visit a doctor, as this may be signs of some serious problems. Some conditions, which need immediate medical aid include pain in the eye, dizziness, mental confusion, feeling of nausea, increasing headache or blurry vision.


Sudden onset of an arc of Flashing light on the periphery of an eye can be due to detachments, which are a result of some other underlying cause. Detachments, most regularly happen because of aging, with the retina shifting to fragile and more brittle as one gets older. However, an acute injury to the eye too can cause the condition.

Apart from flashing lights on the periphery of your eye, there are areas in the eye unit with different symptoms which will follow a separated retina.


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Team PainAssist
Team PainAssist
Written, Edited or Reviewed By: Team PainAssist, Pain Assist Inc. This article does not provide medical advice. See disclaimer
Last Modified On:March 2, 2022

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