Flashing lights and zigzag lines: when it is migraine, not the eyes
No headache, no red eye, nothing to see, and yet your child describes a shimmering, spreading zigzag line that lasted about twenty minutes and then cleared. Here is how to recognise an ordinary migraine aura, and the short list of features that mean today, not this week.
- Migraine visual aura is generated in the brain, not the eyes, and classically appears as a shimmering, zigzag pattern that spreads gradually over minutes before clearing completely.
- It does not need a headache to count: children often have the visual aura on its own, with a mild headache, or with a headache arriving up to about an hour later.
- A single aura symptom typically lasts five minutes to an hour, spreading and changing shape rather than appearing instantly, and always resolving back to normal vision afterwards.
- Aura confined to one eye rather than the whole field of view, aura lasting over an hour, new weakness or numbness, the worst headache your child has ever had, a headache that wakes them or comes with morning vomiting, a change in behaviour, or a new squint or double vision, need same-day assessment.
- Migraine itself is a paediatrician's or paediatric neurologist's field to diagnose and treat; an eye examination checks that the eyes and the optic nerve are healthy, which is a different and narrower job.
He was doing his homework and looked up to say he could see a shimmering zigzag line drifting across the edge of his sight. It lasted about twenty minutes, then it was gone. His head did not hurt. Nothing about his eyes looked different, before, during or after. That combination, a strange visual event with no eye that looks wrong and often no headache at all, is why an eye clinic can feel like the obvious first call. It is usually the right instinct, and it is usually migraine.
This article is about telling an ordinary migraine visual aura from the small number of things that need to be seen the same day, and about being honest with you that migraine itself is not, in the end, something I diagnose or treat.
My child says he saw a zigzag line, then it disappeared. What was that?
That is very likely a visual aura, the most common form of migraine aura and the one that shows up in the overwhelming majority of children and adults who have aura at all. The classic shape is a small, bright, jagged line near the centre of sight, sometimes described as a fortification pattern because it resembles the zigzag outline of a castle wall on old maps. It usually starts small, spreads gradually outward over several minutes, and can leave a patch where sight is dimmed or missing in its wake before it clears completely. Children more often describe it in less textbook terms: shimmering, sparkling, a broken rainbow, a squiggle that grows. The description matters less than the pattern, which is that it moves, it spreads, and then it resolves fully, leaving vision back to normal.
Is something wrong with his eyes if he sees this?
No. A visual aura is generated in the brain, in the part that processes what the eyes send it, not in the eyes themselves. This is why an aura is usually seen the same way in both eyes at once, even though a child often cannot tell you that at the time and simply says "my eye" when they mean their vision. That single-eye versus both-eyes distinction is genuinely useful, and it is one worth checking calmly rather than assuming: if you can, ask your child to cover one eye and then the other during a similar episode, or afterwards describe whether the shimmer seemed to fill the whole view or sit to one side. Migraine aura affecting only one eye, called retinal migraine, is a recognised but distinctly uncommon pattern, and because a true one-eyed visual disturbance can also come from the eye or the retina itself, it is treated more cautiously and is worth a same-day eye examination to be sure the eye itself is not the source.
Does it have to come with a headache to count as migraine?
No, though that can come as a surprise. Migraine aura is formally recognised as its own event, and children in particular quite often have the visual aura with a mild headache, a headache that follows later, or no headache at all on a given occasion. When a headache does follow, it typically begins during the aura or within about an hour of it ending. A child who has the zigzag pattern repeatedly without ever developing much of a headache is not having "not quite migraine": that pattern is accounted for within the same classification, and it does not make the visual event any less worth mentioning to a doctor the first time it happens.
How long should this last, and when is the timing itself a worry?
A single visual aura symptom typically lasts somewhere between five minutes and an hour, most often gradually building and then fading over ten to twenty minutes rather than switching on and off like a light. Two features of timing are worth holding onto. The aura should spread and change rather than appear instantly as a fixed shape or a fixed blind patch, and it should fully resolve, with vision back to completely normal afterwards. An episode that arrives suddenly as a static spot rather than a spreading, moving pattern, or one that drags on well past an hour without clearing, or that leaves any part of vision permanently affected, does not fit the ordinary pattern and is worth same-day assessment rather than watching it happen again.
What tells me this might not be an ordinary migraine aura?
A short list of features changes an ordinary, if alarming-looking, visual event into something needing to be seen the same day. Go to the emergency department, or ring your paediatrician urgently, if the visual disturbance is confined to one eye only rather than affecting the whole field of view, if it lasts longer than an hour without clearing, or if it comes with any new weakness or numbness, especially on one side of the body or face. The same applies to a headache that is the worst your child has ever had, a headache that wakes them from sleep or is there first thing with vomiting in the morning, any real change in your child's usual behaviour or alertness, or a squint or double vision that appears alongside or after the visual symptoms. None of these features is common, and most children who describe a shimmering, spreading, fully-clearing visual disturbance with no other symptoms are describing an ordinary migraine aura. But this is the list that earns urgency, because it is true, it is serious when present, and it is something you can actually check for at home before you ring anyone.
If it's migraine, is that something the eye doctor treats?
Migraine, once the eyes have been checked and found healthy, belongs to your paediatrician or, where headaches or auras are frequent or unusual, a paediatric neurologist. That is not me passing the question along to avoid it: migraine is a whole-brain condition with its own diagnostic criteria, its own pattern of triggers, and its own range of preventive and as-needed treatment, and the doctors who manage children's headache disorders day to day are the right people to take it from here. What an eye examination adds, and it is worth having done once a child describes an aura for the first time, is confirmation that the eyes themselves are structurally healthy and that the optic nerve at the back of each eye looks normal, which rules out the small number of eye causes that can occasionally produce similar visual symptoms and reassures everyone that the visual system generating the aura has nothing wrong with it that a light and a lens can find. Any medicine used for migraine prevention or an acute attack should be decided and prescribed by your child's paediatrician or neurologist, matched to your child specifically, never chosen from a list at home.
What should I actually do the next time it happens?
Stay calm and time it. Note whether it seemed to affect one eye or the whole view, whether it spread and changed shape or stayed fixed, how long it lasted from start to finish, and whether any headache, weakness, or change in behaviour came with it or after it. A first episode, with none of the same-day features above, is worth a routine visit to your paediatrician with that description in hand, not an anxious wait to see if it happens again. If it repeats, the timing and pattern you have noted becomes exactly what a paediatrician or neurologist needs to reach a diagnosis, and an eye check along the way, particularly if the description ever sounds one-eyed rather than two-eyed, is a reasonable and useful thing to have done. Children who have a headache disorder like this sometimes also have light sensitivity worth reading about separately in the child who hates bright light, and a different, near-work-triggered headache pattern is covered in the homework headache that is actually an eye problem, which is worth ruling out if the visual symptom only ever turns up over a book. And if what your child actually describes is a second image rather than a shimmer, that is a different presentation covered fully in what it means when an older child says they are seeing double.
- It affects one eye only, rather than the whole field of view.
- It lasts longer than an hour without clearing.
- New weakness or numbness, especially on one side of the body or face.
- A headache that is the worst your child has ever had, or one that wakes them or comes with vomiting first thing in the morning.
- A real change in your child's usual behaviour or alertness, or a new squint or double vision alongside it.
Common questions
My child says he saw a zigzag line or flashing lights, then it disappeared. What is that?
Does something need to be wrong with the eyes for this to happen?
Does it need a headache to count as migraine?
How long should the zigzag or flashing pattern last?
What tells me it might not be an ordinary migraine aura?
Is migraine something the eye doctor diagnoses and treats?
What is a retinal migraine, and is that what this is?
What should I do the next time it happens?
- International Headache Society, ICHD-3 · 1.2 Migraine with aura (diagnostic criteria) · ichd-3.org
- International Headache Society, ICHD-3 · 1.2.1 Migraine with typical aura · ichd-3.org
- EyeWiki (American Academy of Ophthalmology) · Ophthalmologic Manifestations of Migraines · eyewiki.org
- NHS · Retinal migraine · www.nhs.uk
- Alder Hey Children's Hospital NHS Foundation Trust · Headache (symptom checker, red flags) · www.alderhey.nhs.uk