Flashing Lights in Your Vision: When Is It an Emergency?

Seeing flashing lights in your vision can be unsettling. Many people describe them as flickers, sparks, zig zags or brief flashes at the edge of their sight, often appearing suddenly and without warning.

In many cases, flashing lights are harmless. However, sometimes they can be a sign of something that needs urgent attention. Knowing the difference is important.

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What do flashing lights in vision look like?

Flashing lights can appear in different ways, including:

• Brief flashes or flickers, often in the peripheral vision

• Sparkles or lightning like streaks

• Repeated flashes when moving your eyes or in the dark

• Shimmering or zig zag patterns

They may come and go, or appear suddenly and persist.

Common causes of flashing lights

Posterior vitreous detachment (PVD)

This is the most common cause, especially as we get older. The vitreous is the gel inside the eye, and over time it naturally shrinks and pulls away from the retina. This tugging can stimulate the retina and cause flashes of light.

PVD is very common and usually harmless, but it does need checking to make sure no retinal damage has occurred.

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Flashes associated with floaters

Flashes are often linked with new floaters. While floaters alone are usually normal, flashes and floaters together increase the importance of having your eyes examined promptly.

Migraine or ocular migraine

Some people experience flashing or zig zag lights as part of a migraine, sometimes without any headache at all. These are often described as a kaleidoscope pattern, and the visual symptoms usually:

• Affect both eyes

• Last between 10 and 60 minutes

• Have a shimmering or geometric pattern

These symptoms are generally not related to the health of the eye itself, but should still be discussed if they are new.

When are flashing lights an emergency?

You should seek urgent eye care if you experience flashing lights alongside any of the following:

• A sudden increase in floaters

• A dark shadow, curtain or veil coming across your vision

• Loss of part of your visual field

• Flashes that are persistent or worsening

• Flashes following trauma or a knock to the head or eye

These symptoms can indicate a retinal tear or retinal detachment, which requires urgent treatment to prevent permanent vision loss.

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Retinal detachment and why speed matters

The retina is the light sensitive layer at the back of the eye. If it tears or detaches, vision can be permanently affected if treatment is delayed.

Early detection is key. If caught quickly, treatment is often very successful and vision may remain unaffected.

Should flashing lights always be checked?

Yes. Even if flashing lights turn out to be harmless, it is important they are assessed properly. An eye examination allows us to:

• Examine the retina in detail

• Check for tears or weak areas

• Monitor changes over time

• Refer urgently if needed

  
  

If you have never experienced flashes before, or they feel different to anything you have had in the past, it is always worth getting checked.

What will happen at the eye examination?

If you attend with flashing lights, your optometrist may:

• Take a detailed history of your symptoms

• Dilate your pupils to examine the retina thoroughly

• Use advanced equipment, such as Optomap wide field imaging, to assess eye health

• Decide whether monitoring or urgent referral is needed

You may be advised not to drive for a few hours after dilation, so it is worth planning ahead.

Reassurance and next steps

While flashing lights can feel alarming, the majority of cases are not serious. The key is not to ignore them, especially if they are new, sudden or changing.

If you are experiencing flashing lights in your vision and are unsure what to do, it is always better to seek medical advice. Prompt assessment brings reassurance when everything is fine, and swift action when it is not.

Hayley Brunsden

Founder & Optometrist

CBTR Opticians