S4:Ep1 – Light Sensitivity and Migraine


Voice-over: Welcome to Spotlight on Migraine, hosted by the Association of Migraine Disorders. Join us for fresh perspectives by medical experts and advocates as we explore the spectrum of migraine and dig deeper into this complex disease.

This episode is brought to you by our generous sponsor, Impel NeuroPharma. 

Light sensitivity is one of the most common migraine symptoms, but why does it happen? Find out as Dr. Rani Banik explains causes of light sensitivity as well as tips for managing this symptom.

Dr. Rudrani Banik: Hello, my name is Dr. Rudrani Banik. I also go by Dr. Rani for short. And first I wanted to thank the Association of Migraine Disorders for inviting me to speak today. My topic is light sensitivity and migraine. 

But before I delve into this topic, I first wanted to give you a little bit of background about myself. So I am a board-certified ophthalmologist. I’m also a fellowship-trained neuro-ophthalmologist. And as a neuro-ophthalmologist, I take care of many patients with migraine and many of whom have visual symptoms of my migraine. So I would say about 50 percent of my patients have migraine and/or some other headache syndrome. 

And not only that, I myself am a chronic migraine sufferer. And so I have experienced many of the symptoms which my patients go through, and I have certain insights into some of their symptoms because, again, I have dealt with them as well. And so I’m very excited today to share with you of my thoughts on light sensitivity and migraine. So let’s get started.

So light sensitivity is also known as photophobia. Now, if you break down the word photophobia, photo means light and phobia means a fear of, so basically a fear of light or aversion to light. Now, in patients who have migraine, this means that they are bothered by light that would not otherwise be bothersome, and this happens even when the person is not having a migraine attack. Now, light sensitivity can also occur in individuals without migraine, so without any symptoms of headache or migraine. 

Now, this light sensitivity can trigger pain. It can trigger pain in the eye itself, but it can also trigger headaches. And so there is a connection there between the eye and the brain that I’m going to be explaining to you about.

So in terms of photophobia and migraine, it is a very common symptom in patients with migraine. If you think about the many symptoms of migraine — the most common being headaches, light sensitivity, sound sensitivity, nausea, and vomiting — light sensitivity comes second only to headache in terms of the frequency of the symptom in migraine patients, so extremely, extremely common. 

And, actually, during an actual migraine attack, up to 90 percent of people with migraine suffer from light sensitivity. Now, even between attacks, up to 75 percent of patients with migraine will have light sensitivity. And also, as I mentioned earlier, light sensitivity can be a trigger for migraine as well, and it’s been shown to be a trigger in up to 40 percent of patients with migraine.

Now, what causes light sensitivity? First of all, this diagram shows you how light comes into the eye, and then it gets focused onto the back of the eye, a layer of cells called the retina. And the retina is basically a direct extension of the brain. It’s light-sensitive tissue that carries impulses that ultimately connect back with the brain. 

Within the retina, there are many different types of cells, and basically there are cells that are sensitive to different wavelengths of light. And so here in this diagram, you have the photoreceptors. You have rods and cones, and these rods and cones are responsible for sensing color, light versus dark, form, motion, etcetera. 

And then there are other cells, which are — it’s this very, very interesting story. There are other cells that were relatively newly discovered. So these are ipRGCs, intrinsically photosensitive retinal ganglion cells. I know it’s a mouthful, ipRGCs. But these cells were initially believed to have existed back in the 1920s, but they were not actually discovered until after 2000.

And so there’s been a lot of really interesting work done with these cells, and these cells are the cells that are believed to be responsible for light sensitivity. And the reason is because these cells capture certain wavelengths of light that, ultimately — there are pathways that connect within the brain that connect up with pain centers within the brain. And so these ipRGCs send signals through the optic nerve — from the eye through the optic nerve to the brain. 

Their main role is actually to help regulate our sleep-wake cycle, our circadian rhythm, but they also connect with two pain-sensitive areas in the brain: the thalamus, as well as the trigeminal nucleus caudalis, or TNC. And these are structures deep, deep within the brain. And this — specifically, the trigeminal nucleus caudalis — is also implicated in migraine. So there’s the connection there: so cells from the eye connecting through the optic nerve deep within the brain to the relay center in the brain, which is the trigeminal nucleus caudalis, which helps to modulate pain of migraine. 

Now, the trigeminal nerve itself and its nucleus plays a major role in migraine. It has many different branches, the trigeminal nerve. It also goes to branches of blood vessels, it goes to the face, it goes to the scalp, to the covering of the brain. It also interconnects with nerves that go to the back of the neck, and also branches of the trigeminal nerve go to the sinuses. 

So light sensitivity can potentially — if it activates the trigeminal nucleus caudalis — can actually cause changes in vasculature in the brain. It can cause pain in the face. It can cause neck pain. It can even cause sinus symptoms. So, many, many interconnections here, some of which we still don’t fully understand, but the general pathways have to do with the trigeminal nerve. 

And just as an extension of that, I did want to mention that CGRP, calcitonin gene-related peptide, plays a major role in the pain of light sensitivity and migraine. Now, there is early research in mouse models, in animal models, that shows the role of CGRP. In one particular study, when certain mice were exposed to light, their levels of CGRP rose significantly. So we do know, again, that CGRP not only is associated with other forms of migraine symptoms, but specifically with light sensitivity. So this is an area of research that still needs to be teased out a little bit, but there is definitely early work that is very interesting.

Now, when during a migraine does light sensitivity occur? Well, the answer is, it can occur at any time in the phases of migraine. So it can occur in the prodrome phase; about 30 to 50 percent of patients with migraine will have light sensitivity in the prodrome phase. It can occur with aura; about 90 percent of people with migraine aura, particularly visual aura, will have light sensitivity during an attack. As I mentioned earlier, 80 to 90 percent of patients with migraine will have light sensitivity. And then it can also persist into the postdrome phase, so that 10 percent of people with migraine and light sensitivity will continue to have it after the actual attack has passed.

Now, beyond this, we also know that light sensitivity can become chronic in some migraine patients. I mentioned earlier that there are patients who have light sensitivity even when they’re not having an actual migraine. And why does this occur? It actually goes back to that trigeminal nucleus caudalis. There is central sensitization within that nucleus. And so the brain basically becomes very sensitive to any type of trigger and, in this case, particularly light triggers. So the threshold for pain is very low, and anything can basically set it off. So that may propagate this chronic light sensitivity and pain associated with that.

So the next question: what types of light may trigger light sensitivity? Well, we know that those ipRGCs, those intrinsically photosensitive retinal ganglion cells, are tuned in to certain wavelengths of light, specifically wavelengths of light within the visible spectrum. So if you think about the rainbow, these wavelengths are on the shorter end of that rainbow, so in the blue range of light. So, again, those ipRGCs are tuned in to those wavelengths, and those wavelengths in particular are associated with the light sensitivity of migraine.

So where do these wavelengths come from? What types of light sources may they come from? Well, basically, both natural as well as artificial sources of light can emit these wavelengths. Now, the highest emitter of these wavelengths of light is actually the sun. However, many artificial sources of light, particularly fluorescent lights, as well as some of the energy-saving lights that we all use in our homes — LED lights, light-emitting diodes; CFL lights, compact fluorescent lights — all emit this type of short-wavelength light. So, potentially, these lights may be triggers for light sensitivity and migraine. 

Also, our devices all emit this type of short-wavelength light. So any type of device, whether you’re using a phone, a smartphone, a tablet, a computer, a laptop — even television screens emit short-wavelength light. So exposure to any of these devices may potentially trigger light sensitivity, may even potentially trigger a migraine attack.

Now, beyond the sources of light, other kind of forms of light may also trigger light sensitivity. So, particularly, glare — glare coming off of water on a very sunny day or snow, for example. I’m sure some of you have probably experienced this. I know I have. And then also, specifically, flickering or pulsating lights also trigger light sensitivity, so, for example, strobe lights, overhead fluorescents that flicker. 

And also, many people don’t realize this, but our screens also flicker. They flicker at a very, very fast rate that our eyes may not be able to see, but our brains can pick up this invisible flickering of the screen. And the reason why our screens flicker is because they’re designed to save battery life. So they’re constantly going on and off, on and off. However, that flickering can trigger light sensitivity as well. So it can be really quite challenging for people who are light sensitive to live in today’s day and age because we are exposed to all of these different sources of short-wavelength light plus flickering lights basically all the time. 

So before I move on to ways to treat light sensitivity and manage it, I did want to just mention that migraine is not the only condition that’s associated with light sensitivity. So there are a number of other ocular as well as neurologic conditions that are associated with light sensitivity, for example, corneal issues. The cornea is a layer in the very front of the eye. 

Corneal issues such as dry eye or infections or inflammations of the cornea can trigger light sensitivity because the cornea is densely innervated by branches of the trigeminal nerve. So that’s why there is that light-sensitivity connection. And so, really, the underlying cause of light sensitivity needs to be really teased out and that underlying cause treated. So if it’s migraine or migraine plus other conditions, both of those underlying causes need to be treated for light sensitivity.

So, moving on — how to manage light sensitivity. Well, first of all, the simplest thing to do is to avoid bright lights or flickering lights, but it may not be very practical. But some of my patients do — when they are very light sensitive, they do prefer to be in an extremely dark room, close all the blinds, no external light whatsoever, but, again, not the most practical. 

Now, if someone is on migraine medications, very often the migraine medication itself may also not just treat the migraine and the headache, but it may also treat the light sensitivity, particularly the CGRP inhibitors because of the connection I had said before with CGRP. So there have not been fully designed clinical trials yet on this, but there has been anecdotal reports that the CGRP inhibitors, of which there are six currently FDA approved, may also benefit light sensitivity. Hopefully, there will be some exciting research coming out soon on the actual benefits of the CGRP inhibitors for light sensitivity. 

Now, what about dark lenses or tinted lenses? Well, many of my patients do wear dark sunglasses, and, yes, this can help with light sensitivity. But the type of tint that has been clinically proven for light sensitivity is an FL-41 tint. Now, I have some here. These are FL-41 tinted glasses. I don’t know if you can see, but they have a slightly pinkish or rose color to them. And these, again, have been shown in clinical studies to help reduce not only the light sensitivity, but also the blinking and eye discomfort and pain associated with light sensitivity. 

There are different manufacturers of FL-41 tinted glasses. I actually prefer the wraparound style when I’m outside because not only do I get a wide protection here, but I also get a little panel on the side that helps prevent some of that stray light coming in from the sides.

Some of my patients, I actually do prescribe for them tinted contact lenses. There are a few manufacturers I work with, and these contact lenses, some of them do have the FL-41 tint. Others have other tints that are designed to help block out those short-wavelength lights. The contact lenses have been very effective for both many of my migraine patients as well some of my concussion patients. So if you’re interested in that, please discuss this with your eye care provider about tinted contact lenses for light sensitivity.

Now, moving on, I’ve also found screen filter apps to be quite effective. Some of these screen filter apps are able to not only block out — internally remove the short-wavelength lights, but also remove the flicker rate of your screen. So, very, very helpful. 

Blue-blocking glasses, the jury is still out on this. There have not been any clinical trials that have really shown the benefit of blue-blocking glasses for light sensitivity. For sleep, yes, to help with sleep disorders, but not specifically for light sensitivity.

What I will say about blue blockers — I actually have a couple of pairs here. There are many different manufacturers on the market and many different gradients of blue blockers. So some are clear, some have a yellowish tint, and some have a darker tint. You can see this is a red tint. Some are almost amber or orange. 

But the tint does matter because when you put on a lighter tint and if you look at your screen, if you can still see the color blue, that means that that blue blocker is not blocking out 100 percent of the blue light. It’s probably blocking maybe 20 to 30 percent of the blue light or the short-wavelength light that may be triggering the light sensitivity.

However, if you put on a darker pair, when I look at the blue on my screen, I don’t see any blue at all. So I know that this blue blocker is probably blocking out almost 100 percent of the blue that’s coming from my screen. So if I did choose to wear a blue blocker for light sensitivity, I would probably choose a darker-tinted blue blocker. 

And then, finally, I do want to mention about green-light therapy. So there are studies that have shown that for migraine, short wavelengths as well as longer wavelengths, meaning red wavelengths, can cause discomfort in migraine patients. However, green wavelengths of light can be therapeutic. They actually don’t tend to trigger light sensitivity and may actually help relax and calm and soothe the eyes. So there is some early research to support this. 

So I just also wanted to mention something about chronic dark adaptation. Now, some of my patients, they are such sufferers of light sensitivity that they just prefer to be in the dark all the time, in a dark room, with dark sunglasses, with a wide-brimmed hat.

Now, of course, this can be an effective strategy for the short term, but I do not recommend it for the long term because the more dark-adapted one is, the more light-sensitive they become when they are exposed to light. And it’s a similar situation of when you’re — let’s say you’re watching a movie and you’re in a dark room for two hours, and you go outside into the light. It is very, very uncomfortable initially. So it’s the same concept where chronic dark adaptation may actually prime you for more light sensitivity and decrease your threshold for light sensitivity. So I try to wean my patients off of their dark-adaptation state either with less-and-less-tinted glasses, more and more exposure to light. 

So, finally, I just want to end with this. If you do have light sensitivity and it’s very severe and you’re not responding to treatments, be sure to see either an ophthalmologist or even a neuro-ophthalmologist to really try to get to the bottom of it, to make sure that there isn’t something else that could be contributing to the light sensitivity. So definitely get that checked out.

So thank you so much for listening and for, again, the Association of Migraine Disorders for inviting me to speak. I do share a lot of tips on migraine and visual symptoms, as well as eye health, on my social media, so feel free to follow me on Instagram @dr.ranibanik. On Facebook, I have a private Facebook group called Eye on Migraine, and you’re welcome to join. And I also have my YouTube channel, Rudrani Banik MD.


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