What Causes Flashing Circles and Lights in Vision? Square Glow Flashers Explained

Understanding Square Glow Flashers and Flashing Circles in Vision

Seeing flashing lights, circles, or jagged lines in your field of vision can be alarming. However, these visual disturbances have several potential causes, some of which are harmless. One of the most common is a square glow flasher.

Square glow flashers manifest as flickering shapes, often described as looking like an old television set with static. They typically last only briefly, ranging from a few seconds to minutes. While disruptive in the moment, these luminous flashes are generally not a cause for concern.

Read on to learn more about what square glow flashers are, what causes them, and when flashing circles or lights warrant an eye exam.

What are Square Glow Flashers?

Square glow flashers are momentary visual disturbances that look like flickering or flashing shapes, grids, or bursts of light. Some characteristics of square glow flashers include:

• Brief duration - Typically last seconds to minutes
• Non-solid shape - Often described as grids, netting, squares, dots
• Monocular - Usually occur in one eye at a time
• Can seem to dance or bounce
• No associated pain or headaches
• Not affected by eye movements or blinking

These luminous visual episodes are one type of entoptic phenomenon. Entoptic events stem from within the eye rather than an external light source.

In contrast, photopsia refers to seeing flashes of light coming from outside the eye. Migraine headaches commonly cause these types of flashes.

What Causes Square Glow Flashers?

Square glow flashers are generally harmless visual aberrations caused by temporary pressure changes within the gel-like vitreous inside the eye.

Changes in Vitreous Gel

The vitreous is a clear, gel-like substance that fills the interior cavity of the eye. It helps maintain the round shape of the eyeball and permits light to pass through unobstructed.

As we age, the vitreous slowly liquefies and detaches from the inner wall of the eye. Clumps or strands can form within the shifting gel. These vitreous opacities cast tiny shadows onto the retina, producing the flashing or flickering shapes.

Sudden eye movements may also cause vitreous traction on the retina, temporarily disrupting light transmission to the retina. The spontaneous vitreous waves also come across as luminous flashes.

Posterior Vitreous Detachment

Partial detachment of the vitreous gel from the retina frequently precedes square glow flashers. This event, known as posterior vitreous detachment or PVD, allows vitreous fluid to move more freely within the eye.

As the vitreous tugs during a PVD, it can stimulate the retina intermittently. This manifests as short-lasting flashes, sparks, and flickering shapes like grids or circles.

Benign Eye Floater Symptoms

Small specks or strings floating through the field of vision often precede or coincide with square glow flashers. These floaters represent vitreous opacities casting shadows onto the retina.

Like flashers, benign floaters result from normal age-related vitreous liquefaction. They are a symptom of PVD and signal harmless changes within the eye.

Are Square Glow Flashers Serious?

For most people, temporary square glow flashers are not a serious concern. They represent a natural aging process as the vitreous detaches from the retina.

However, flashing lights and floaters do warrant an urgent comprehensive eye exam if they appear suddenly and are accompanied by other symptoms. This helps identify potential vision-threatening conditions requiring prompt treatment.

When to Seek Emergency Care

Seek emergency eye care if flashing circles, grids, or jagged lines appear suddenly and are paired with:

• Sudden increase in floaters
• Loss of peripheral or central vision
• Veil or curtain over any part of vision
• Halos around lights
• Eye pain or headaches

These associated symptoms may indicate a retinal tear or detachment, which can lead to permanent vision loss if not treated immediately.

Causes of Troubling Visual Symptoms

Concerning medical causes of flashing shapes and lights accompanied by other symptoms include:

• Retinal detachment - A medical emergency where the retina separates from the back of the eye.
• Retinal tear - A retinal hole that can progress to detachment if not repaired.
• Vitreous hemorrhage - Bleeding into the eye from conditions like diabetic retinopathy.
• Ocular migraine - A headache accompanied by visual auras like flashing lights.
• Eye injury - Trauma can cause bleeding or retinal damage.

Any sudden, dramatic changes in vision require prompt medical assessment to identify potential threats to vision.

Are Floaters Related to Square Glow Flashers?

Small specks drifting through the field of vision, known as floaters, often precede or accompany square glow flashers. Like flashing shapes, most floaters are harmless indicators of vitreous changes.

However, a sudden onslaught of new floaters can signal a posterior vitreous detachment and associated retinal tear in some cases. This requires prompt evaluation.

Typical benign floater characteristics include:

• Small and dot-like appearance
• Drift slowly when the eye moves
• Translucent or cobweb-like
• No effect on underlying vision

Worrisome floaters are described as:

• Appearing suddenly in large amounts
• Dark or opaque in color
• Accompanied by light flashes
• Obscuring vision

Any sudden changes in floaters should be evaluated urgently to identify a potential retinal tear or other condition requiring quick treatment.

Can Flashing Shapes Indicate Retinal Detachment?

Flashing circles, lights, or zigzag lines can occasionally be the first visual symptom of a detached retina, though this is uncommon.

A detached retina is a serious event where the retina lifts away from the back of the eye. This causes rapid, permanent vision loss if not treated immediately with surgery.

People at highest risk for retinal detachment include:

• Those with extreme near-sightedness
• People who have had cataract surgery
• Those with a family history of retinal detachment
• Individuals with prior retinal injuries or tears

Flashing shapes or lights alone are rarely cause for alarm. But they warrant urgent evaluation if accompanied by:

• Sudden appearance of dark floaters
• Blurry vision
• Veil or shadow over any part of vision
• Loss of peripheral or night vision

Prompt treatment of retinal tears and detachments can help restore vision and avoid permanent impairment.

Can Ocular Migraines Cause Flashing Lights?

Transient flashing circles, zigzags, or geometric patterns can be symptomatic of a type of migraine headache called an ocular or retinal migraine.

This occurs when blood flow temporarily decreases to the retina, creating flickering visual distortions that precede head pain. These flashing auras typically last around 30 minutes before subsiding.

Ocular migraine characteristics include:

• Visual symptoms in both eyes
• Flashing lights, zigzags, or looping lines
• Gradual onset over 5-20 minutes
• Complete resolution with no permanent vision changes
• Headache afterward, usually one-sided

While alarming, migraine flashing auras are ultimately harmless to vision. Keeping a headache diary helps identify events as migraine-related.

When to See an Eye Doctor About Flashing Lights

Brief square glow flashers or flashing shapes that come and go are typically benign. However, schedule an urgent eye exam if flashing circles, lights or jagged lines appear suddenly and are paired with other symptoms like:

• Increase in dark floaters
• Partial loss of vision
• Curtain-like obstruction of vision
• Eye pain
• Headaches

While rare, these additional symptoms may indicate a retinal tear, detachment or other condition requiring emergency care to prevent permanent vision damage.

See an optometrist or ophthalmologist promptly if:

• Flashing shapes are frequent or persistent
• New floaters arise suddenly
• You experience migraine headaches with visual auras
• You have diabetes, nearsightedness or other retinal condition

A comprehensive dilated eye exam can identify any underlying eye issues and determine if flashing lights need treatment.

Preventing Flashing Lights in Vision

Little can be done to outright prevent temporary square glow flashers, as they stem from age-related vitreous changes. However, maintaining eye health may lower risks of certain vision-threatening causes of flashing lights.

• Get regular dilated eye exams
• Control diabetes through diet, exercise and medication
• Wear protective eyewear during sports or risky work
• Eat eye-healthy foods rich in vitamins and omega-3s
• Quit smoking to reduce retinal damage risks
• Limit UV exposure by wearing sunglasses outside

While rarely indicative of trouble, be sure to get evaluated promptly if new symptoms accompany sudden flashing lights or floaters in your field of vision.

The Takeaway

Brief square glow flashers or flashing circles are typically harmless visual aberrations stemming from age-related vitreous changes inside the eye.

However, seek urgent medical care if new light flashes or spots are accompanied by loss of vision, eye pain, or headaches, which can signal a retinal tear or other sight-threatening condition.

With proper attention to your symptoms, flashing lights do not have to cause undue alarm. But urgent evaluation for accompanying vision changes can help safeguard your eyesight.

Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult with a healthcare professional before starting any new treatment regimen.