Ocular light toxicity and the requirement for protection
Date of publication :
This video shows the round table discussion of eight international eye health experts with a diverse range of professional and geographic backgrounds (North America and four European countries) who met in Paris (November 2016) to discuss blue light toxicity. The aim of the meeting was to share personal experience in this field, identify areas to focus on, and explore solutions for managing potential blue light toxicity.
The event was chaired by Prof. Dot. The panel captured a wide range of domains in eye health care, including academic and applied research in both the preclinical and clinical settings, as well as patient management in surgery and private practice. The meeting was driven by an increasingly pressing need to deepen knowledge among our eye health professionals on the biohazards of light exposure – and specifically on the dangers of and the need for protection from blue-violet light.
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Part 1 - Ocular light toxicity and the requirement for protection
Prof Dot: We want to comment on the duality of blue light and how the beginning of the spectrum is harmful and the end of the spectrum is beneficial, do you want to comment on this?
Dr Tolentino: Well, the blue light is a spectrum. We go from very high-energy light, which is the ultraviolet, to the blue-violet (which is between 400 and 450), and then you probably have the blue-turquoisespectrum (which is 450 to 500) and then you have the green spectrum after that.
Prof Dot: So where exactly is the beginning of the blue light, can you specify, because there are controversies about the beginning?
Dr Tolentino: The beginning is, again, it’s like trying to say what is the difference between fructose, glucose, mannose and lactose etc. You really can’t, it’s a spectrum. They all will do the same thing, just at higher or lower levels. Now, if you catch the wavelengths of light which are more in the violet or blue range, these are probably the most harmful to our bodies our eyes and so on and so forth. But if you go to the lower levels, that’s when you get into the beneficial yet potentially harmful side effects and you sort of have to balance these things off. The problem with blue light is that it affects not only our eyesight but it also affects our circadian rhythm, as well as our metabolism. And as a result, we really don’t know enough, we have to study more, that’s why we’re here. We’re researchers. We need to find out more about the balance between the different spectrums of light.
Prof Korobelnik: Do you think there’s a difference between natural sunlight and artificial light that comes from a bulb or a screen or whatever? Because the exposure to screens is quite new. I mean, six or seven years ago, the exposure was different because the screens were different on computers, and tablets and smartphones were not as available. So there is a big change between natural sunlight exposure and artificial light. Does that make a difference to you, or to anyone else?
Prof Dot: On the iPad you have the spectrum of the different light. You can see the sunlight and you can see the LED exposure too, is it different in the spectrum?
Prof Korobelnik: Yes, you see that the peak of blue light from sunlight is the same as the peak from LED light, so is it relevant that the narrow peak is different from the broad spectrum?
Dr Tolentino: Yes. Radiation exposure is always taken as power over time. Daylight, I mean, how many people sit outside looking at the blue sky? Maybe if you don’t have a job, I don’t know, so our exposure when we do historical exposure, is very difficult. It’s very difficult to measure exactly how much light you are receiving. The problem with computer screens and iPads is that the light goes straight to our macula and we stare into them. Now, the power may be a little less, but the time frame is much longer. I have some patients, well, some children, who probably spend 10 hours in front of these things. And what do you do? I tell them to wear protective lenses or not do it at all.
Prof Dot: We obviously have to talk about the lumens and the power, yes. So we can understand the mechanisms.
Dr Tolentino: On the graphs, as he pointed out, the peak is around the same as daylight, so it’s completely different – children in the early 1900s didn’t eat that much sugar. Now I know for a fact that my generation eats a lot of sugar, we have it everywhere, and look what’s happening to the population. That’s what is going to happen to the next generation because they’re being exposed to something that in small quantities is good. We need exposure to sunlight, we need vitamin D for growth. But we don’t need that much in that much exposure.
Dr Colombo: This is something we have to consider looking at this data. Not just children use these devices, we have low vision patients who use them too much and their retina is compromised, and we need to also think about these patients.
Prof Dot: And do you think the blue light from TVs is harmful or not?
Dr Tolentino: It’s the same, it’s just that we’re farther away. With radiation it’s how close you are. We tend to watch TV from several feet away. I know that my children, they do this [holds iPad close to face], I don’t know why. They’re not myopic, they just do it, I don’t know why, and it always gives me a little knot in my stomach when they do that, because that’s a lot of radiation.
Prof Wolffsohn: And there’s an inverse square for radiation, so the closer you bring it, it really does increase enormously.
Dr Tolentino: Absolutely.
Part 2 - Today's challenges in the face of increasing blue light exposure
Dr Tolentino: Our exposure to indoor blue light is unprecedented in human history. I don’t know if it’s bad or if it’s good, but we’ve got to be aware of it.
Prof Dot: And do you think that the discomfort and the screens are related to blue light or not, or can we conclude that a lot of factors are involved, not only the blue light? I think a lot of factors are involved.
Prof Wolffsohn: I think if you’re talking about computer vision syndrome, a lot of factors are involved.
Prof Dot: Okay.
Dr Tolentino: But blue light is possibly a main factor there.
Prof Wolffsohn: I think the answer is that it’s very difficult to know because we’re looking at this, we have more blue light but we have a closer working distance, we’re staring for longer periods, we’re keeping our eyes open, we’re blinking less. The difficulty is teasing out which of those factors are causing this discomfort. It is probably a combination of factors, and I think it’s difficult at the moment to say that it is definitely blue light causing the discomfort rather than other changes to the tear film. There is an increasing understanding of what they call computer vision syndrome, or various other terminologies used for it, but trying to tease out which factors are causing that is not really available current literature.
Dr Tolentino:Blue light is the main wavelength of glare, that causes glare, at least if you look at the spectrum of wavelength of light you will see that it causes three to four times more glare than other wavelengths of light. Glare itself is a big problem for a lot of my patients, especially those who have had cataract surgery, it causes them distress, and that is what I see in my population, especially in those who have macular degeneration, the glare is much more prominent when they’re using these devices than when they aren’t, so a lot of them just don’t.
Prof Dot:We have to consider cumulative exposure. We know that everyone is concerned by this, more than 90% of individuals use a computer and we spend more and more time on them. So do you think we have to reduce exposure for kids, or we have to recommend more protection with reducing the time, or both? What is your…?
Prof Wolffsohn: It would be difficult to reduce exposure because so much of their world is focused around it. I use the term ‘screen addicted’ because a lot of our youth and adults are, and I’m sure in all of our lives we spend more and more hours in front of the screen, even if it’s in surgery, now we have tablets and computer controls. So I think the exposure is not something we are going to change. Things we can change are either the protection or the light itself. But again, LEDs have so many benefits in terms of an economic way of producing light. I very much doubt that that will change in the near future.
Prof Dot: Do you think that LED is harmful for the retina?
Mr Picaud: Well, for the LED, it’s clear that there is no regulation. And yet, it’s very difficult to know what kind of LED you are buying, so you don’t know if there is a big peak of blue light in the LED that you will be buying. So it’s very difficult because of this absence of rules, at least in Europe, so the concern was really to look at some populations that might be more at risk, like young people, or aged people, so we were very concerned that this absence of regulation could be very harmful for some populations at risk. What we see also in these LED illuminations is that, in fact, the blue-turquoise light is much dimmer, and in fact blue-turquoise light is also controlling the size of the pupil. Pupil constriction is really triggered by this blue-turquoise light and, in fact, you see that there’s really a lower intensity in the blue-turquoise. So the pupil constriction is really less and therefore might allow the blue-violet, more toxic light, to enter the eye. So this balance between the blue-turquoise light and the blue-toxic light that might be changed also, as it might introduce more toxicity to the retina. In our case, I think we have to remember that, when we go outside, the blue light intensity is really very high, so this is the most blue light we see in our lives, we have to remember that whenever we go outside we have to protect ourselves from this blue light.
Part 3 - Latest preclinical evidence on blue light phototoxicity (research work done in the Paris Vision Institute)
Mr Picaud: The starting point of this work was that it has been demonstrated, or at least there is evidence, that sunlight is toxic and can induce age-related macular degeneration, sunlight and especially blue-violetlight, the blue spectrum in sunlight. So what we wanted to do was really to try to define which wavelengths are really toxic in the blue light, because as we have heard there’s blue light close to the UV but there’s also the good blue light for our circadian rhythm, so we wanted to know whether we could suppress some of the blue light in the spectrum in order to create some kind of prevention for age-related macular degeneration. So what we did was to take a cellular model of age-related macular degeneration, and this model takes cells of the retinal pigment epithelium and loads them with A2E. A2E is a compound that is found in lipofuscin, so this compound is accumulating with age in retinal pigment epithelium and it’s known that this compound can induce some phototoxic damage. However, it’s only been shown with blue light and it was not clear which wavelengths can induce this type of damage. So what we did was to take this retinal pigment epithelium loaded with A2E and expose them to 10 nanometres of light, and do this from 390 up to 520 nanometres, and also have a control in the visiblerange at 630 so we would see which of these wavelengths are toxic for the retinal pigment epithelium. And what we can see is that, in the range of wavelengths at 420, 430, 440, and 450, we see that we can induce apoptosis, or cellular degeneration, in these retinal pigment epithelium cells with these wavelengths, so this means that the band from 415 to 455 is toxic to the RPE in this model of age-related macular degeneration. Of course, it’s a model, but we tried to also use light intensities that reach the retina. We can at least know that the more toxic wavelengths in this model, are the ones we defined from 415 to 455, and we have confirmed this result more recently by showing that reactive oxygen species are produced by exactly these wavelengths, so we can show not only that we have toxicity, we can also show the production of these species, we can show that also we have mitochondrial damage in this same model, and we also show that in fact, when we use this radiation, we also have a decrease in the defence metabolism, the glutathione is decreased in these cells. So it really suggests that this blue-violetlight is inducing a lot of reactive species, a decrease in the oxidant defence and also a mitochondrial defect.
Prof Dot: So wecan conclude that we have strong evidence with research on phototoxicity.
Part 4 - Challenges in getting clinical evidence
Dr Tolentino: We know that blue light is the only photooxidative light. I’ve been studying macular degeneration since I was in seventh grade, and we’ve found out that photooxidation or oxidation is the main player in terms of upregulation of vascular endothelial growth factor, the production of apoptosis in geographic atrophy. We know this, right? And we also know that activation of the complement system and inflammation is what really causes macular degeneration. What wavelength of light does all those things? Only blue light. Blue light will upregulate complement, it will inactivate the complement inhibitory pathways of the alternative pathway, it also will cause photooxidation and cause an upregulation of oxidative products when its lipofuscin, which is a by-product that is a marker for macular degeneration, is exposed to blue light. What more evidence do you need?
Prof Dot: The long-term hazards - this is very difficult to draw a conclusion because the design of the studies isn’t good, so we can’t conclude ? … what is your conclusion?.
Prof Wolffsohn: I think there are some indications, but the studies are not…
Prof Dot: Designed for it?
Prof Wolffsohn: Yeah.
Dr Tolentino: I think the basic science supports that it is hazardous, but the clinical science, well, that’s going to take 20 years.
Prof Korobelnik: To promote protection, you need really strong data. And you have strong data about smoking and lung cancer, and smoking and AMD, but to me at the moment the data about the exposure to blue light and advanced AMD are not very convincing. So there are two options, either you decide to protect yourself or to promote protection because you think that, this may be true, and you don’t want to take the risk, or you wait for strong evidence, but then the strong evidence may arrive too late for a generation of people. So I think that’s the big challenge to me at the moment. What I mean is that there is a gap between science in the lab and human real-life evidence, and what I would like to see is a bridge that is really strong enough in between those two things.
Part 5 - Patient risks and current protective measures
Prof Dot: And what about the selective photoprotection with glasses now or eyewear, what do you think about this? Do you think that photoselective protection is there to block the beginning of the blue light and to transmit the good blue light?
Dr Tolentino: The job of a retinal doctors is to preserve the cones and photoreceptors, and using blue light protection is actually the simplest. Wearing protective eyewear to filter blue light – there’s no toxicity to that. I always recommend blue protective lenses. Every one of my patients gets that recommendation. I’ve been doing that for five years.
Prof Dot: Do you think we can define a population at risk?
Dr Tolentino: That’s why I brought it up.
Prof Dot: So, children? Old people? People with low vision?
Dr Colombo: Yes of course, people with low vision. I think that both children and older people are at risk. Children because they have less filter with crystalline in the lens and the cornea. And on the other hand, older people because they have less retinal mechanisms of protection. So we have to consider protecting both children and older people, even if we know that there is no strong evidence, as we said before.
Mr Picaud: We may wonder whether the poor protection of the eye in young patients is inducing this high rise of lipofuscin in these very young patients, and this lipofuscin we know is very toxic, so if we can reduce this amount in these young patients, we may lower the risk of a long-term effect, as we see that between the ages of 0 and 10…
Prof Dot: There are two periods, yes.
Mr Picaud: The time at which we have very low protection, there is a rise, and we also see it rises when the patients are aging, and we see that the macular protection is decreasing because there is less absorption of the pigments.
Dr Colombo: In my experience, I could say that this could be true maybe not for healthy people but for people who suffer from retinal dystrophy. We know, as Dr Tolentino said, that the blue light affects glare, so in this kind of patient the fact that we use a selective filter for blue light increases visual acuity, it increases contra-sensitivity and decreases the glare, so the visual fatigue is less for those kinds of patients. The other thing we know is that protection is costless from a safety point of view. So if we use some lenses we do not do any damage to the retina, so it is a costless solution. We should consider protecting the eye from this toxic blue-violetlight.
Prof Dot: And do you prescribe antioxidants in order to reduce the progression of AMD? When do you prescribe then? Antioxidants, in Spain - early?
Dr Orduna: Yes, for years I was prescribing all the antioxidants on the market, all the doses of omega-3, 500 mg per day, then 1 g per day, and after that 1.5 g per day and I saw no significant effects. A good part of my patients were religiously taking the medication every days, 3 times a day, and after 5 years several patients developed macular degeneration, so I stopped.
Prof Dot: You stopped when you saw the macular degeneration?
Dr Tolentino: You stopped all of them?
Dr Orduna: Yes.
Prof Dot: Okay. In France?
Prof Korobelnik: I still recommend it, but I also recommend as a supplementation to patients with, for example, advanced AMD in one eye or drusen in the other eye, I usually say to their children and I tell them to stop smoking and to eat appropriate food, because it’s probably more important for the children of the AMD patients, who are 40 or 50 years old, to modify their behaviour.
Prof Dot: And do you start very early, with a small drusen?
Prof Korobelnik: No, I don’t start very early, I normally start when there are large drusen or advanced AMD in one eye.
Dr Lamoureux: I think it’s okay to prescribe them like with AMD on one side and the other you have big drusen.
Prof Wolffsohn: In the UK, in terms of educating the eye care practitioners of the future, we encourage all of them to talk to their patients about nutrition, because it’s not just an elderly thing, and as we’ve said as the benefits may well be much earlier than that, and it is about nutrition, so if they’re not eating well, and a lot of patients will admit that they are not eating well, there is that supplementation to help them.
Part 6 - Precautionary principle and recommendations
Dr Lamoureux: In the clinical setting that we have every day, now people ask us what we can do to not have maculopathy. It’s not really an easy to give them a response because the protection they are asking for needs to start younger.
Dr Tolentino: Well it is really an insidious problem that we’re having. We don’t know the hazards of high-energy visible light because we like that kind of light. What I’ve been studying for the last five years is the notion that high-energy visible light is similar to sugar for diabetics. Back in the 50s and 40s, we thought that sugar was good for you, and as a result we placed a lot of high-fructose corn syrup into our diets. Now the common knowledge is such that sugar is bad for you, it causes chronic disease, blindness, heart attacks, strokes … and I believe that high-energy visible light has all the makings of the sugar of our generation.
Prof Wolffsohn: I think there are a couple of important things here. One, these are relative intensities, so although we are seeing a peak at 100% on the blue for the LEDs, the amount of light is a lot less than you get from sunlight. But actually, Dr Tolentino’s point about sugar, if you look at, for example, aboriginal populations that have now been exposed to sugar, their rate of diabetes is through the roof. So it is actually about our body’s ability to deal with the relative balance of nutrition for example, and the balance of light is now changing. So we seem to be putting much more blue into the eyes, and other wavelengths, and again that long-term exposure is something we don’t fully understand in terms of its potential for damage. We know that sunlight does damage because of its pure intensity - this is a very different concept. Here now we have much lower intensity but a longer duration and a very different balance across the spectrum.
Dr Colombo: It’s a balance - we do not need to create alarm on blue light, but it’s something we need to consider because the evidence in the model is very strong. And it’s not only a preventive measure, but for some patients, there is also something that could improve the quality of life. So we have to think of these lenses not only from a preventive point of view but also from a way to increase the quality of life of some patients, like retinal dystrophy as I said before.
Dr Orduna: I don’t prescribe filters because I think there is no in vivo evidence of the use of blue light blockers that it’s better for my patients.
Dr Tolentino: I believe that everybody should have some protective wear.
Prof Dot:We can recommend protection, because we have the evidence.
Dr Tolentino: For blue-violet, yes.
Prof Dot: Yes, for blue-violet, we can conclude that we can recommend protection as early as possible.
Dr Tolentino: I would, definitely in children.
Prof Dot:In children, and after cataract surgery too.
Prof Korobelnik: It’s just do we take a strategy to prevent a risk that may occur, or wait to be sure before starting to prevent and that’s a big challenge. But I think there’s probably no risk to start preventing, but there may be a risk to delaying prevention. So you should stop smoking, have a good diet, and use filters.
Part 7 - Future moves
Prof Korobelnik: What I would like to have and what I see in the future is that we could do genetic testing to identify the high-risk population. So we could let the non-risk population do what it wants, and for the high-risk genetic population, you put a lot of pressure on them to prevent with whatever they want, to prevent the risk. Because this has been shown by the Rotterdam team: if you identify a high-risk population and you prevent, you reduce the risk to the normal population. So genetic risk is not something you have to consider as very strong and irreversible. If you modify other risks, especially diet, the genetic risk goes down. I think that genetic testing is the challenge for the next ten years, but on the other hand, it’s not that if you have a bad profile you will develop the disease. For AMD, there are well-known factors that you can modify, like food and smoking, and I think that promoting protection from blue light is something that we discuss, but if there is one thing to do, it is to stop smoking, if you smoke, and the other thing is to eat appropriate, good food with omega 3 and carotenoids etc. And this is well established: if you have an appropriate diet, you decrease the risk, even if you have the high-risk genetic profile, so it’s not because you have the genetic profile that you will get the disease for sure, it’s complex.
Dr Colombo: I agree.
Prof Dot: You can be aware.
Dr Tolentino:The genes are just pre-disposing genes. They don’t say that if you have the genes you will get the disease. You describe two modifiable factors: smoking and diet. The issue is that I have many, many patients, and I’m sure you all have, here in this room, patients who don’t smoke, and eat very, very well, and still get macular degeneration. Right? So we’ve got to find out more modifiable factors, that’s why we’re in this room, correct?
Prof Korobelnik: Correct.
Dr Tolentino: I think we need to educate doctors and we need to educate patients in terms of what they need and how much they need. It should just be tailor made.