Blue light and the retina
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@lorna I wrote that f.lux "basically" works that way, but I probably over-simplified it, sorry. F.lux is of course more sophisticated than that in controlling the colour temperature.
But I've noticed that people often think that f.lux is able to apply an arbitrary spectrum filter, adjusting specific wavelengths. What I was trying to get across is that f.lux can't attenuate eg. 440 nm light, while still passing 480 nm light, as could be done with an optical filter; it can only adjust the relative brightness of the red, green, and blue pixel elements.
People working in the optometry industry vs. the lighting industry might be expected to have rather different opinions on whether LEDs contribute to age-related macular degeneration (AMD). Having "not been proven to cause damage to the retina" isn't the same as having been proven to have no long-term effect.
I think this 2004 paper says it reasonably well:
Evidence from animal studies confirms blue light's damaging potential but the results are not directly applicable to macular degeneration in humans. Studies of human macular pigment density and the risk of AMD progression following cataract surgery lend further weight to the hypothesis that blue light exposure has a role in the pathogenesis of AMD but the epidemiological evidence is equivocal. On balance the evidences suggests but does not yet confirm that blue light is a risk factor for AMD.
There does seem to be a lot of fear, uncertainty, and doubt out there, with sensational articles implying that white LEDs and screens produce some kind of harmful radiation that's different from what you get from ordinary sunlight. That is of course nonsense.
But the argument that computer screens aren't nearly as bright as the sun, and therefore pose no problem, isn't so convincing. Five hours a day of summer sunlight exposure as a teengager increases the risk of AMD later in life. What about the office worker in front of a computer eight hours a day for forty years?
That person may have less risk than someone who works outdoors, but it's not unlikely that both would benefit from eye protection. The above paper says AMD "is a major health problem in the developed world accounting for approximately half of all blind registrations", and there are no viable treatment options.
The fact that the IEC62471:2006 "Blue Light Hazard" spectrum exists, suggests that it's a concern. The recomended "safe" exposure levels are based on short-term acute effects, in those people working with lasers and so on. They say nothing about chronic long-term exposure. The guide for implementing the EC Directive 2006/25/EC says:
Most exposure limits are based on studies of thresholds for acute effects, and derived from statistical consideration of these thresholds. [...] Chronic effects often do not have a threshold below which they will not occur. As such, the risk of these effects occurring cannot be reduced to zero.
Typical UV coatings aren't designed to protect against retinal damage. A better example would be:
https://fluxometer.com/rainbow/#!id=filter/GUNNAR PPK&action=BlueLightHazard
...which appears to reduce the potentially retina-damaging < 450 nm light by 50% or more, while having relatively little effect on the ~490 nm melanopic range.@herf I can't quite imagine where you'd be getting those numbers from, 30% "doesn't matter", and "If you want to have a noticeable effect on retinal health you'd block 90% or more". We know that smoking five cigarettes a day for a year or two probably won't have much effect on long-term health. A pack a day for thirty years certainly will. With blue light, we just don't have those kinds of numbers yet.
I'm not suggesting people need to go around wearing amber-coloured glasses all day, I'm sure that's a bad idea. But AMD is a serious problem for a large proportion of the elderly population, and there's evidence, if not conclusive, that chronic exposure to ~440 nm light over a lifetime is a major factor. Taking reasonable measures to limit that would seem to be prudent, along with getting enough sleep, eating vegetables, and flossing.
As the science matures, I hope we'll see industry taking steps to help people reduce the risks of AMD. For example, computer screen manufacturers could develop better pigmentation for the blue pixel filters. Eyeware manufacturers could create more effective protective lens designs. The issue is not something to panic about, but definitely worth keeping an eye on...
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Elhem, I value your comments and your participation in the forum, but I don't like the direction this conversation is taking.
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You're not "probably" oversimplifying it, you're posting incorrect information. What you are describing an optical notch filter, which is incredibly expensive. This is not how eyeglass coatings work.
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We work closely with people in both the optometry and lighting industries, and we're not talking about opinion, we are talking about proven facts and measurable, repeatable data. I see plenty of incorrect information in both of these industries. Their sales numbers often depend on marketing materials that consistently mislead, frighten, and confuse consumers. For example, the OP also posted wrong information: "Blue light emissions from computer and cell phone screens have been proven to cause damage to retinal cells over time." This is not a true statement. Might they cause harm? Possibly. Should people use common sense? Of course. But it is our responsibility to talk about what is known, and we should not spread fear / uncertainty / doubt when we can talk about facts instead.
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You are confusing the IEC62471:2006 blue light hazard spectrum with the spectrum related to AMD - they are not the same thing. Blue Light Hazard exists to measure something that is a specific concern, to a specific population working with potentially dangerous equipment.
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There are hundreds of studies about this topic, many with unclear results, so please let's not have a squirtgun fight with cherrypicked lines from paywalled abstracts.
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Everyone basically agrees that blue light can cause damage to older retinas (this appears to be due to blue light's reaction with the pigment lipofuscin, which is found in damaged, older tissues). Some studies show that there is not a risk factor with light seen in younger eyes but related to light seen later in life. But, the lens yellows with age, and by age 60 it filters out more blue light than Gunnar's glasses.
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People at risk for AMD (like me - I have a vested interest in this particular topic) should be getting information about this from ophthalmologists, not optometrists, and not internet forums.
I know Mike has some things he wants to say, so I will stop here.
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I agree with you that we have no evidence for long-term effects, except for studies on time spent outdoors (Boulder Dam). And the risks are not evenly distributed: people with aphakic eyes should take special precautions, and those with diagnosed AMD should make every attempt to keep it from progressing.
But what we can do is compare screens to known lights and known standards.
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Computer screens are designed to emulate paper viewed under bright office lighting, and compared to fluorescent light reflected by paper, it is extremely hard to argue that LED screens cause more harm. The typical office fluorescent produces "blue" at 437nm, and the typical backlit screen produces "blue" at 455nm, and it produces very little energy below 430nm. The higher-energy from a fluorescent has a bigger effect in the retinal harm studies. Also, turning down the blue primary makes almost a perfect low-pass 480nm filter. Moving the blue primary from 450nm to 460nm like OLED might have a small effect, but there is no magic in optical filters in this case.
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Light outdoors is dramatically brighter (even with sunglasses on). By "dramatically" I do not mean 30% brighter, I mean 100x brighter.
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You are making a common mistake, in guessing that "effect sizes" are proportional to luminance. So most people guess, well, if I turn this light down by 20%, I will have 20% less sleep disruption/retinal harm/sunburn/etc. But this is a serious mistake. The thing to understand is that the effect sizes for all these things are in fact logarithmic and so you must make a 10x change in the input to have a reasonable effect on the output. If you had to say, instead, "these glasses reduce the harmful effect by 0.05%" you'd sound silly, so people should not make hyperbolic claims about filters that reduce a certain wavelength by 10%.
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I have read IEC62471, and it specifies testing a light source at 500lux, to estimate how much harm will be caused. There is essentially no viewing distance for a monitor at which you can achieve 500 lux. This standard says LED displays are "exempt" from light-based retinal harm.
If you move your monitor away by 1", or dim it by one tick, you'll make a bigger difference in the physics than most filters on the market, so I think these filters are extremely silly, and I think the marketing should not be allowed.
If there is an effect due to light at these irradiance levels, the mechanism will be due to exposure after dark and deep into the night, because no "normal" exposure is reasonable to cause retinal harm.
I stand by my assertion that removing 90-99% of the light should be a target for anyone seriously trying to offer a "fix" for these "problems" (both of which are unproven).
All else is snake oil, and we should call it that.
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Here is a summary by one of the actual experts on retinal harm (Dirk van Norren). The "outlier" data for rodents around 500nm is for albino mice, and so for everyone else, what this graph says is "don't stare directly at the sun". Much of the current standards and eyewear claims are based in the Ham 1976 data, I remember.
Just to be clear, retinal harm is indicated here at doses "smaller than" 100 J/cm2.
Apple's 27" Cinema Display makes 0.0000125 W/cm2, so a 12-hour exposure of that is 0.54 J/cm2. But we do not have a way to even guess at why seeing "normal luminance" sources would have an effect.
You can never say never, but you can say the evidence is extremely uncompelling.
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And at least the UK is finally cracking down on bogus advertising:
http://www.dailymail.co.uk/news/article-3292789/Boots-glasses-claim-misleading.html
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Lorna, I'm just an amateur, and here to learn. All I know is what I've read online. A year ago, I didn't even know there were any issues with blue light at all. If I've misunderstood something, I'm happy to be corrected! And if I post something that disagrees with what you've said, I don't mean to challenge you, I'm really just asking a question and hoping to learn from the discussion.
As I'm getting on in years, and facing some health issues, I wish I'd done some things differently when I was younger, and had more information. Wikipedia makes everyone an "armchair expert", which can be annoying, but does have value. I'm hoping to learn to take better care of my health, and maybe help others a little to understand things, along the way. I'm pretty sure it's clear to everyone in these forums that you and Michael are the only real experts here...
@lorna said:
- You're not "probably" oversimplifying it, you're posting incorrect information. What you are describing an optical notch filter, which is incredibly expensive. This is not how eyeglass coatings work.
I was trying to describe a longpass filter, something that passes only wavelengths longer than eg. 460 nm:
Rosco creates all kinds of different curve profiles with their filters, by using different combinations of dye. My point was about what seems to be a common misperception among some users that f.lux (or any software) is able to apply a filter attenuation curve of any arbitrary shape, and control specific wavelengths across the spectrum; whereas actually it only has control over the three broad RGB filter channels. It can't reduce the 440 nm light more than it reduces 480 nm light, while a physical filter or lens coating could.Whether that would have any actual value or not, even with 100% attenuation, I admit that I don't know. I'm not sure that anyone really does. The AOA states in the context of LED lighting, "blue-violet light can be harmful to the eyes, specifically the retina. It is a risk factor for the onset of age-related macular degeneration", while Ian Ashdown says flatly "at the light levels encountered with typical electric lighting, there is no evidence to indicate this". Lorna says "blue light during the day is fine", but Michael says "If you want to have a noticeable effect on retinal health you'd block 90% or more" - though he thinks it's unnecessary. It can be difficult for someone like me to figure out what common sense really is. "On balance the evidence suggests but does not yet confirm that blue light is a risk factor for AMD", written by opthamologists, seemed like a reasonable position. It's maybe not too far out of line with the rest of what you wrote?
The bottom line is that I wear UV protective lenses and try not to spend too much time in the sun, like most people. I'm not really worrying about retinal damage from blue light. But I'm starting to think that maybe sitting in front of the window most of the day, looking at the sky above my computer screen, is something I might consider changing.
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@herf said:
- Computer screens are designed to emulate paper viewed under bright office lighting, and compared to fluorescent light reflected by paper, it is extremely hard to argue that LED screens cause more harm.
Oh, absolutely! The idea that computer screens and smartphones are somehow more dangerous than being in other types of daylight-balanced lighting, or daylight itself, is utter nonsense. As I've been googling some of the products, I'm seeing this implied over and over. Re-reading what I quoted from the AOA, they're implying the same thing. And clearly @elisadelina has bought into that. That's just wrong.
The story about Boots pushing £70, 20% blocking lenses to protect you from your "gadgets", does seem ridiculous. I agree that companies shouldn't be allowed to make health benefit claims for their products, when there's no conclusive evidence to support them. To be honest, I hadn't really looked at what's on the market. I only know that it should be possible to make a 90%+ reduction longpass filter lens, without being extremely expensive, and that it would give more precise control over the cutoff frequency than can be achieved by modulating the LCD filters in a monitor. In other words, to block the wavelengths shorter than 450 nm that may (or may not) be harmful, while passing the 480 nm and longer wavelengths that are beneficial in the daytime. I guess I assumed that's what they were doing.
Even if they were though, it seems that the evidence for blue light's contribution to AMD isn't conclusive enough for companies to legally make claims of medical benefits.
Still, it seems to me there's some evidence about long term chronic retinal effects of blue light in general (not specifically computer screens), and that some sort of eye protection measures could be beneficial. Again, I'm not talking about acute effects, which is what IEC62471 and I think Van Norren are dealing with, 12-hour exposures and so on, but fifty-year exposures. Figuring out what those measures should be though, is beyond me at this point. It is difficult for me to understand the "95% or nothing" position.
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Elhem, it is not a question of challenging me, it's a question of ensuring we post the most accurate information we can. I agree with you about both the benefits to easy access to information and the trouble of armchair experts. We must all be very aware of making incorrect assumptions. This is a difficult topic, and an area of active, ongoing research. Nobody knows all the answers to these questions.
Everything from stronger nightly melatonin production to reduced levels of ADHD to the prevention of myopia has been linked to appropriately bright daytime light exposure. It helps mitigate the effects of artificial light at night too.
I will tell you that I have begun spending more time sitting in front of windows and looking at the daytime sky, making sure that I see bright light at the appropriate time of day. There is not evidence that says that anyone must filter 90% of light in a normal, healthy eye. But for someone who has to pay closer attention to their retinal health, filtering 10% of inappropriate light will do nothing. Because you have concerns about this I strongly recommend you bring this up with an ophthalmologist, who can give you the best advice for your needs.
It would be a terrible disservice to spread fear and uncertainty about healthy people seeing light during the day, and we will not do that on our forum.
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@lorna said:
Everything from stronger nightly melatonin production to reduced levels of ADHD to the prevention of myopia has been linked to appropriately bright daytime light exposure. It helps mitigate the effects of artificial light at night too.
I'm not sure what you've done to the forum, but I LOVE selecting text, clicking reply, and have it auto quote, that's SO much easier! Anyway, I have ADHD, and I'm near sighted so both of those strike my interest. Could you expand a bit on those topics?
I've seen several "links" or correlations to bright light in the daytime preventing myopia, but I've not seen much about ADHD. I love this thread by the way, you're really explaining so much of this, and I love when we can pull information out of you and @herf so thanks!
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@Tungsten_smooth An incredibly high percent, around 75% of children and adults with ADHD also have delayed circadian timing. It's not strictly related to light timing - lots of ADHD patients have irregular meal times, and there is a lot of research looking for other internal clock components - but there's a very strong correlation with sleep issues and ADHD. Sleep deprivation in adults in lab conditions can induce textbook ADHD symptoms (more here: http://www.nytimes.com/2013/04/28/opinion/sunday/diagnosing-the-wrong-deficit.html?_r=0).
We already know that getting bright light at the right time of day can help improve sleep quality and sleep timing. There seems to be an association between ADHD and sunlight levels too:
http://www.brainclinics.com/association-adhd-intensity-sunlight-adhd-prevention@lorna
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@lorna Well thank you for that, I'm quite sure I have... sleep onset insomnia, and it's, well, it's not getting any better. I've noticed in recent years (6-7+ years) it will take at least an hour (but usually about two) for me to truly feel relaxed and want to sleep. There's just so many interesting things to think about-it's not stressful stuff, it's mostly what I did that day, what I need to do tomorrow if there are tests, and then I think about my life and technology after that. Damn brain won't turn the hell off!
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@Tungsten_smooth Ahh, sorry to hear that. :(
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You also asked about the sunlight and myopia connection as well, and I needed to look up some of the sources for you here because I know less about this topic.
The retina produces dopamine in daylight. And we know that dopamine / dopaminergic meds change the shape of the eye (atropine can even slow down myopic progression in kids).
A lot of people with ADHD report photophobia, and wear sunglasses(47%), which might even lead to additional sleep delays. About 70 - 80% of kids with ADHD also have visual acuity problems.
Here are some sources, some are paywalled, but if you are still a student your library might have access:
High Prevalence of Self-Reported Photophobia in Adult ADHD, Kooij and Bijlenga 2014:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4261727/Light Levels, Refractive Development, and Myopia - A Speculative Review, Norton and Siegwart, 2013: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3742693/
An updated view on the role of dopamine in myopia, Feldkaemper and Schaeffel, 2013:
http://www.sciencedirect.com/science/article/pii/S0014483513000432I realize I sound like everyone's grandmother right now but if you want to do something simple to help your retinal health and make it safer to see blue light, the easiest thing to do is eat leafy green vegetables. Spinach and so on. Orange and yellow is okay too - carrots and corn will also help. Mammals can't make the pigments needed for best retinal health so we must get them from plants. Anything green (and from plants, so green m&ms don't count) will provide your body with the right materials to help keep your eyes healthy. More here: https://en.wikipedia.org/wiki/Carotenoid
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@Tungsten_smooth said:
@lorna Well thank you for that, I'm quite sure I have... sleep onset insomnia, and it's, well, it's not getting any better. I've noticed in recent years (6-7+ years) it will take at least an hour (but usually about two) for me to truly feel relaxed and want to sleep. There's just so many interesting things to think about-it's not stressful stuff, it's mostly what I did that day, what I need to do tomorrow if there are tests, and then I think about my life and technology after that. Damn brain won't turn the hell off!
I have some tips that I would love for you to try:
- Near bedtime, write all of these things down on paper. Don't use a computer to do it: you have to use a pen or a pencil. It's a massive difference between writing and typing.
- After that, spend a few minutes sitting quietly in silence with your eyes closed. Or instead of silence, use white noise to raise the sound floor to drown out distracting noises. Calm yourself and let your mind do what it needs to do. The longer you do this, the better.
- As often as you want each day, spend a handful of minutes in total silence with your eyes closed. It doesn't have to be perfect silence because you can instead use a white noise sound machine to drown out distracting noises, like the Dohm. The longer each session is, the better.
- You might even benefit from taking melatonin right before bed. I have mild Autism and I read years ago that people with Autism naturally produce insufficient amounts for proper sleep. So if I don't take my melatonin, then I end up with the same problem you have. Do you have Autism at all? You might. Lots of people have it and don't realize it.
- Increase your intake of Folate. This can help a little with anxiety. 400 to 800 mcg per day is plenty. Don't overdo it. I like Solgar's Folate, the one that's in the form of Metafolin (L-methylfolate). They are dry tablets that are meant to be swallowed, but can be easily chewed up and have a mildly sweet sugar-like flavor.
- Use some breathing exercises to your advantage.
- Try to leave at least a 3-hour gap between the last thing you ate or drank and when you go to bed. Going to bed too soon after your last meal of the day (which, for most of us, is our biggest and hardest-to-digest meal) is the reason most people have a hard time going to sleep. It's also one of the causes of nightmares and waking up too hot in the middle of the night - even if the room is cold.
- If you exercise regularly, then try to leave at least a gap of at least 6-8 hours before bedtime. It is absolutely mind-blowing how long it takes for the body to truly calm down after a workout. If you can't do this, then you may need to use special relaxation techniques and exercises after a workout, but that can't replace working out earlier in the day, but it would be better than not exercising anymore. Think about what it would be like to live outside in the wild hundreds of miles away from artificial light: you naturally get your exercise during the middle of the day looking for food, but the later part of your day is spent coming back to your living area and eating the food you found before you lose the light that the sun provides. This is hardwired into us.
- Try a sound machine instead of sleeping in silence. I use the Dohm, and I'm serious: I sleep better these days because of it.
I can't think of anything else.
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@lorna said:
@Tungsten_smooth An incredibly high percent, around 75% of children and adults with ADHD also have delayed circadian timing. It's not strictly related to light timing - lots of ADHD patients have irregular meal times, and there is a lot of research looking for other internal clock components - but there's a very strong correlation with sleep issues and ADHD. Sleep deprivation in adults in lab conditions can induce textbook ADHD symptoms (more here: http://www.nytimes.com/2013/04/28/opinion/sunday/diagnosing-the-wrong-deficit.html?_r=0).
Well having ADHD seems quite shitty going by that link. There's so much that can go wrong--that article highlights a lot of downsides to ADHD and they are all awful. Thankfully I don't have trouble breathing in my sleep--I'll never know if I did as an infant, I'm not sure my parents checked that, and I never asked, too young at the time. It says that could have a permanent neurological effect! That's HORRIBLE! Something we just take for granted could strongly impact your life in such a negative way forever! That's enlightening! Great!
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@Tungsten_smooth said:
@lorna said:
@Tungsten_smooth An incredibly high percent, around 75% of children and adults with ADHD also have delayed circadian timing. It's not strictly related to light timing - lots of ADHD patients have irregular meal times, and there is a lot of research looking for other internal clock components - but there's a very strong correlation with sleep issues and ADHD. Sleep deprivation in adults in lab conditions can induce textbook ADHD symptoms (more here: http://www.nytimes.com/2013/04/28/opinion/sunday/diagnosing-the-wrong-deficit.html?_r=0).
Well having ADHD seems quite shitty going by that link. There's so much that can go wrong--that article highlights a lot of downsides to ADHD and they are all awful. Thankfully I don't have trouble breathing in my sleep--I'll never know if I did as an infant, I'm not sure my parents checked that, and I never asked, too young at the time. It says that could have a permanent neurological effect! That's HORRIBLE! Something we just take for granted could strongly impact your life in such a negative way forever! That's enlightening! Great!
My mom said that I had a breathing incident when I wan an infant, and I have Asperger's Syndrome. I doubt that this is why I have it because it's something a person is born with, but still, I'm sure that incident damaged me somehow.
You can have trouble breathing while you're sleeping and not know it. If you are told that you snore while you're sleeping, then that's a sign that you could be having trouble.
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@lorna said:
"Among adults with ADHD, the majority has an (extremely) late chronotype and a delayed sleep phase (7, 8)."
Here's the beginning of that paragraph, but you may or may not be able to recite all this if you've read it before:
"From chronobiology studies, we know that there is a link between retinal function and the circadian rhythm. " That's the sentence that really kicked it off.Well that just went from vision right back to sleep! That just shows how important it is. A paper about vision just starting discussing sleep. How did that happen? I guess eyes and sleep are related..., but, yes, that definitely explains my late sleeping schedule, shucks. I tell you, you just poured a bunch of negative information into my screen! Thank you though, it's worth it to learn. At least I can be aware of all this stuff, I can't thank you enough!
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I think the article is just talking about the light that enters your eyes while you are awake. You know, blue light, red light, bright light, dim light, all the stuff that we already know. I think they're just describing it differently.
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@TwoCables Thanks, I was going to post that I was confused as to why the subject changed so abruptly but you really picked up on that quickly, thanks. Yeah, that seems to be the case, it's discussing how the light goes and works it's magic in the brain.
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@Tungsten_smooth Yes, it's all related very closely. The retina is really important to circadian rhythms. It's a lot to take in, especially when some of it rings true. But I hope you won't feel too much like it's all bad news. Reading too many studies online can have that effect sometimes...
@lorna
