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When I, or both, it changes what you can do.
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Welcome to Margarine Heroes, a podcast for anyone living with margarine and wondering
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why nothing has fully worked yet.
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I'm Diane Ducarme.
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Over the past 7 years, I've helped hundreds of people living with margarine.
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What I've learned?
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No two margarine stories are exactly the same, and none of them are simple.
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That is why, in this podcast, we explore margarine from many different angles.
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Food, hormones, stress, sleep, the nervous system, emotions, and much more, through the
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lens of both modern science and traditional Chinese medicine.
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A quick note before we start.
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What we talk about here is educational.
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For anything related to diagnosis or medication, please keep working with your doctor.
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Now take a deep breath, and let's dive in.
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In this episode, you will learn why seeing something on one side of your vision does
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not necessarily mean it is happening in one eye, and why classic margarine aura actually
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comes from the brain.
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What makes true retinal margarine different, and why it is extremely rare, and why doctors
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should not diagnose retinal margarine until other causes of temporary vision loss in one
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eye have been considered.
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A very simple test you can do during a familiar visual episode that can help you describe
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your symptoms much more accurately to your doctor.
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Because when it comes to visual margarine symptoms, one eye versus both eyes really
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So stay with me till the end, because by the end of this episode, you will know exactly
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what to observe the next time a visual disturbance happens, and why one tiny detail can help
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your doctor distinguish an ordinary visual margarine aura from something that needs a
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very different investigation.
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So for this episode, I'm going to stay mainly with the Western medical perspective, because
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the distinction between visual aura and retinal margarine depends on anatomy, on neurology,
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and ophthalmology.
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Traditional Chinese medicine uses a very different system of thinking, and does not separate
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these visual symptoms in the same way.
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So rather than force an Eastern explanation onto a Western diagnostic distinction, we'll
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keep this episode focused on where the visual symptoms are coming from, and why one eye
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versus both eyes matters.
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So let's start with what this actually feels like.
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You're reading, maybe working at your computer, perhaps you're making dinner, and suddenly
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something is wrong with your vision.
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Maybe there's a bright shimmering line, maybe you see zigzags, maybe there's a crescent
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of broken looking light, and maybe a small blind spot begins growing.
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Or perhaps the opposite happens.
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Instead of seeing extra lights and shapes, part of your vision simply disappears, and
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your immediate thought may be, something is wrong with my eye.
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And that assumption makes perfect sense.
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After all, you experience the symptom through vision.
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But here's the surprising part.
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In most visual margarine aura, the problem is not actually in the eye.
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It is occurring in the brain, and understanding that is the key to today's entire episode.
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So what does ocular margarine actually mean?
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Now the phrase ocular margarine is confusing, because people use it to describe different
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Someone might say, I had an ocular margarine yesterday.
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But medically, that could mean they experienced a classic margarine visual aura.
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Now when I say classic, I really want to acknowledge, there's nothing classic about the feeling
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of having an aura, right?
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But they could also mean, symptoms are affecting one eye, or they may be describing something
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else entirely, that has never actually been diagnosed as margarine.
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And so the more precise distinction is between margarine with visual aura, where the visual
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phenomenon is generated in the brain, and retinal margarine, where the visual disturbance
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is genuinely limited to one eye.
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And these two should not be treated as interchangeable, they're not.
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So the International Classification of Headache Disorders defines retinal margarine as repeated
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attacks of sort of fully reversible visual disturbance in one eye, such as flashing phenomena,
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a blind area, or temporary blindness.
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And importantly, it also states that other causes of temporary vision loss in one eye
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And it describes retinal margarine as an extremely rare cause of transient loss of vision in
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And the word rare, it really matters, because visual margarine aura is relatively familiar,
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but true retinal margarine is not.
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So in a classic margarine aura, the eyes, they actually may be fine.
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So to understand classic visual aura, what you need to do is to imagine the pathway of
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So your eyes receive light, and that information travels through the visual system toward the
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back of your brain, where an area called the visual cortex is going to help to construct
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what you actually perceive as sight.
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And during a margarine aura, researchers have identified an unusual wave of electrical and
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chemical activity that travels slowly across the surface of the brain.
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So it's called cortical spreading depolarization.
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And I've recently done a podcast about that, if you're interested.
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There was a 2025 review in Nature Reviews Neurology that described spreading depolarization
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as the electrophysiological process underlying margarine aura.
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And so it moves slowly across the cortex and temporarily changes how nerve cells function.
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And if that wave crosses the part of your brain processing vision, your visual world
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So you might see something that actually isn't there.
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You might see flashes or sparkles.
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You might see zigzag geometric shapes, a shimmering crescent, or you may temporarily lose part
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of what you can see.
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And because these waves move gradually across the visual cortex, the visual disturbance
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frequently moves too.
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Tiny spots become larger, or a shimmering line is going to expand, or a blind area migrates
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through your visual field.
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And that gradual evolution is very typical of margarine aura.
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Now again, I can't insist enough.
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Typical in a medical sense, not typical in a, wow, this is a non-event.
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This can be very frightening.
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So the International Classification of Headache Disorders describes aura as neurological symptoms
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that usually develop gradually over minutes.
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An individual aura symptom typically lasts somewhere between about five to six minutes.
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Now, this is where people get confused.
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So imagine you see a flashing zigzag on the left side, and naturally you think, it is
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But that's not necessarily what's happening.
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So your brain organizes visual information partly according to visual fields, not simply
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according to the left versus the right eye.
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So a disturbance created in one side of the visual cortex can affect the same side of
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your visual world as seen through both eyes.
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Yet subjectively, it can feel like one eye is affected.
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And this is one reason why people frequently mistake classic margarine aura for an eye
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I have countless number of people who said, oh, you know, and I went to the ophthalmologist
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or to the optometrist and they said, my eyes are fine, but I can't see, but I get this
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So the International Headache Society specifically notes that some people who report a disturbance
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in one eye actually have a visual field disturbance affecting both eyes.
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And so this gives us the most useful question in today's episode.
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If you cover one eye and then the other, is the phenomenon still there?
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And we're going to come back to that.
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We're going to hammer it because you're going to have to do that during the migraine attack.
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So now what is retinal migraine?
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Well, actually it's very different.
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So with retinal migraine, the visual disturbance is genuinely monocular.
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So that means one eye, so not predominantly one side of your visual field, not it feels
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stronger on the left, just one eye.
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And the symptoms can include positive visual phenomena such as flickering or flashing,
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but they can also include negative symptoms such as a blind patch or temporary loss of
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So I'm going to explain what we mean with positive and negative in a minute.
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So the International Classification of Headache Disorders says that these symptoms should
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So they should truly be monocular and generally develop gradually over at least five minutes,
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last from approximately five to six minutes and occur with or around a migraine headache.
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But there is a very important additional condition.
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Other causes of temporary vision loss in one eye have to be excluded.
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So that is what makes retinal migraine a diagnosis of exclusion.
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So there was a 2021 review in the journal Vision that emphasized that retinal migraine
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has historically been confused with terms such as ocular migraine and ophthalmic migraine.
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So for the side notes, as we're clarifying so many things, an ophthalmic migraine is
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an older and quite imprecise term that was referring to migraine with visual aura and
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visual symptoms like the flashing light, zigzags or blind spots caused by the brain rather
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They also emphasized how rare the condition is and the importance of ruling out other
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causes of temporary monocular vision loss.
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So this is where the distinction becomes much more than terminology.
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It becomes a safety issue.
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So why does this one eye vision loss matter so much?
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So suppose somebody says, my vision disappeared for 10 minutes.
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The next question should not simply be, did you get migraines?
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One of the important questions is, did you lose vision from one eye or did part of your
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visual world disappear through both eyes?
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Because temporary loss of vision from one eye can sometimes result from problems with
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blood reaching the retina or optic nerve.
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And so those causes are completely different from classic migraine aura.
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So a 2024 review in Ophthalmology and Therapy explains that temporary monocular vision loss
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can sometimes be caused by retinal ischemia, meaning inadequate blood supply to the retina
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and that appropriate investigation can sometimes be vision saving or life saving.
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And potential causes can include problems with blood vessels supplying the eye, embolic
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disease, inflammation of blood vessels and other ophthalmological or neurological conditions.
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And it's really interesting because just to talk about the East, in the East, definitely
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these things are worked on.
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And it's quite interesting because in the East, even though the distinction with the
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wording is not made, like for thousands of years, these things were actually happening
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and actually being addressed.
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So here again, East and West are really converging, it's just that there's a lot more precision
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of terminology and observation in the West.
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So it does not mean that every visual change in one eye is dangerous, but it does mean
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something very important.
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You should not automatically call temporary one eye vision loss an ocular migraine, especially
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Now retinal migraine is very real, but it's also extremely uncommon.
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And this is worth repeating, retinal migraine does exist, but the diagnosis criteria are
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intentionally very strict.
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So retinal migraine was reviewed in the journal Current Neurology and Neuroscience Reports
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in 2021 and described as an uncommon and still poorly understood migraine condition.
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And their review noted that only a very small number of well-documented cases had appeared
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in the medical literature over the preceding 15 years.
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So the biological mechanism is also much less settled than it is for classic aura.
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So for migraine aura, evidence strongly supports cortical spreading depolarization in the brain.
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And for retinal migraine, researchers have proposed temporary changes in blood vessel
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tone and blood flow within the retina, including retinal vasoconstriction.
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But the evidence remains limited.
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So when somebody says retinal migraine happens because the blood vessels in the eye constrict,
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I would add an important scientific word, maybe.
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It's a plausible proposed mechanism.
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It's not nearly as firmly established as cortical spreading depolarization is in the case of
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Now let's talk about positive versus negative symptoms.
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So this is really a clue that is really worth knowing and that's going to help you diagnose
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things with your doctor much better.
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Migraine aura often gives you what neurologists call positive visual phenomena.
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Positive does not mean pleasant.
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It simply means that something has been added to your vision.
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So like flashing, sparkling, shimmering, zigzagging, moving geometric patterns.
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Now you can also get negative visual symptoms with aura.
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So something is missing from your visual field, but the mixture of moving positive and negative
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phenomena is very characteristic.
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So by contrast, ischemic loss of vision from one eye may sometimes be described more as
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darkness or a gray area or a shadow or curtain coming down over the vision.
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Again, I can so much picture this woman like really saying, you know, I see I have my vision,
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And then on the lower back right, I see there's a gray patch, there's a part of my vision
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And this is essential.
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They're not a home diagnostic system.
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Real patients do not always read the textbook before developing symptoms.
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So if you experience a new episode of genuine one eye vision loss, the safest approach is
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not I know migraines.
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So this must be retinal migraine.
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This is monocular.
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It deserves proper medical evaluation.
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Now, what if there is no headache?
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And so this is another reason why diagnosis becomes really tricky.
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So classic migraine aura can occur without a headache afterwards.
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So somebody can experience 20 minutes of shimmering zigzags, watch them gradually move away, feel
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completely normal afterward and still have experienced migraine aura.
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And so the absence of pain does not rule aura out.
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Retinal migraine, however, is defined more narrowly in the international diagnostic criteria
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and is usually associated with migraine headache.
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So once again, the casual phrase ocular migraine hides a lot of the complexity.
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So you can remember aura can be silent, but a retinal migraine is usually not silent and
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is associated with migraine headache.
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Now, let me give you two examples.
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So Sarah suddenly notices a small shimmering zigzag while reading.
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It expands slowly over 10 minutes.
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It seems to sit on the right side of her vision.
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She assumes it is her right eye.
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But when she covers the right eye, the zigzag is still there.
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Then she covers the left eye.
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And the phenomenon gradually expands and disappears 20 minutes later.
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Now that pattern points much more toward a visual aura generated in the brain.
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Now imagine Daniel.
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Daniel suddenly realizes the vision in his left eye has gone dim.
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He covers his left eye and sees normally through the right.
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Then he covers his right eye and realizes that the disturbance is definitely present
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in the left eye alone.
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And so that is a different situation.
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Could it eventually turn out to be a retinal migraine?
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But because retinal migraine is rare and because the other conditions can cause one eye loss,
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Daniel's first task is not to diagnose himself with retinal migraine.
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His task is to get the monocular vision loss properly assessed.
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And that's why today's distinction matters.
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His task is to get the monocular visual loss properly assessed.
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There's a line I want you to remember.
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So migraine visual aura usually comes from the brain and is seen through both eyes.
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Retinal migraine generally affects one eye.
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And because one eye vision loss has other possible causes, retinal migraine should only
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be considered after those causes have been evaluated.
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And that's the heart of this episode.
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Now you may be wondering what sort of other conditions doctor may consider.
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I'm going to just cite a few words to give you an idea, but the list won't be exhausted.
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We're talking here about retinal vasospasm or optic nerve disorders or retinal tear or
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retinal detachment or giant cell arthritis or retinal artery occlusion.
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To just give you a few ideas, right, of what things need to be ruled out in order to define
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it's a retinal migraine.
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Now here's something incredibly simple you can do today, provided the visual symptoms
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is familiar and you're somewhere safe and you're not driving.
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So when the visual disturbance begins, look at a fixed object or line of text and cover
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your left eye, observe the symptom, then cover it, cover your right eye, observe it again.
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If the flashing pattern, zigzag or blind area remains visible regardless of which eye is
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covered, that suggests the phenomenon is affecting the visual field processed by the brain rather
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than being confined to one eye.
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The simple exercise is also recommended by migraine specialists as a way of clarifying
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whether the visual aura is binocular.
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But remember, this is an observation tool.
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It is not a diagnostic test.
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It is there to get you one step closer to understanding your migraine.
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That's all for today.
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I hope this episode added one more piece to your migraine puzzle.
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Migraine is complex, but it's not random.
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Every time we understand a little more of it, we move one step closer to lasting relief.
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If you'd like to apply what we've discussed to your own life, you can find us by searching
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Migraine Heroes in the App Store or Google Play.
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Look for the green icon with the love heart in the brain.
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Your body has a story to tell.
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Let's keep listening.
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I will be back with you soon.
