LCD Display Discomfort



		LCD Display Discomfort Last revision January 30, 2004. Original text published July 19, 1996. © 1996-2004 Michael C. Battilana. This page also has a PURL for cataloging and bibliographical purposes. Although this article was written with great care, it may reflect personal opinions of the author, which are not necessarily shared by the publishers, who cannot assume any responsibility for mistakes or misprints. Nothing in this article should be regarded as medical advice. If you require medical or other expert assistance, you should consult a professional advisor. Introduction As soon as I heard about LCD displays, and even more after seeing some flat panel monitors at computer shows, I became a fan of this technology. As a computer user sitting in front of a monitor for more hours than the sun shines in the sky, I was very happy that I would soon be able to enjoy a flicker-free and radiation-free alternative to bulky and power-hungry cathode ray tube monitors. That was until I tried them, beginning a story of hard to describe discomfort and an apparently vague relationship with existing research involving factors such as fluorescent light, flickering, lighting, glare, contrasts and patterns. I now refer to this as "LCD Syndrome". First Experience I found out in 1996 that I could not make full productive use of an LCD display (800x600 resolution) for longer than 20-30 minutes, after which I began to feel uncomfortable. This was not easy to describe, because the symptoms were not particularly strong, and they were going against the expectation and conventional wisdom that LCD displays were better than CRTs. I would say it was a combination of slight headache and eye irritation. I normally had no problems with fluorescent lighting, nor with any working environment in general. I do however feel a similar discomfort when standing for some time near certain mosquito killing devices which use a violet fluorescent tube to attract the insects. A friend of mine develops symptoms similar to ones I experienced after only about 5 minutes, and he was the one who led me to the first apparent cause of this: the fluorescent light use for the backlighting of the display. He is a teacher, and the first thing he does when he enters a classroom is to switch off the fluorescent lights. He says he is "allergic" to fluorescent light. When he purchased a notebook with a black and white LCD display he found out that he had the same problem he has with fluorescent room lighting. I personally tried out a variety of LCD displays, from the cheap ones up to the high end, and I also spoke with a lot of people about this, concluding that the issue is surprisingly more widespread than I expected it to be. The feedback I am now receiving from this text also appears to confirm this. Frankly, I was amazed and puzzled as to why none of the reviews of notebooks or LCD displays that I was aware of at the time had ever mentioned this. The first thing that came to my mind is that this is a relatively new technology, and the new parameters that need to be evaluated are not yet part of our testing and buying culture. A second aspect of this issue is that the problem in my experience only develops under real working conditions, rather than when admiring the sharp pixels of an LCD display for a few seconds at a trade show, or testing the LCD viewing angle for a review or in a computer store. According to my personal observations with panels employing this technology, many people cannot work continuously with such a display for as long as they can with a traditional CRT. Some people feel a headache after about half an hour of work in front of an LCD panel, yet they can stay 16 hours in front of a CRT. My situation improved when I conducted tests on word processing tasks with white text on a black background, rather than black text on white background (which, traditionally, on a CRT with a sufficiently high refresh rate is considered to be more ergonomical). I am not a doctor nor an expert in this field, and I did not have a chance to conduct tests on a sample wide enough to be considered significant. The feedback I am receiving may be biased, as it is increasingly based on this article (i.e. people may be finding a description of the problem they have been looking for, rather than an unexpected and new perspective). Yet I am left with this personal feeling that there is "something wrong" with LCD displays that has not been researched or mentioned enough. I hope that these notes of mine can inspire somebody to perform more thorough investigations. Fluorescent Light While everybody appeared to be focused on the "zero radiation" advantage of LCD technology, I could not avoid thinking that, behind the liquid crystals (which the "L" and "C" letters stand for), there was a source of light. This happened to be the same fluorescent light technology which, I knew, was not recommended for use as the only light source in offices. So, if there was something less than ideal about using it too much in an office, how came nobody mentioned this in relation with the fact that LCD display users stare at such lights all day? Checking things like the refresh rates and the frequency peaks of a source of fluorescent light is not normally done with CRT displays, and does not naturally cross one's mind when thinking of liquid crystal displays. The fluorescent light is a separate component from the LCD display, and is never mentioned as part of the final "LCD display" product. Two aspects of fluorescent lighting are in my opinion worth mentioning. Fluorescent lights, like other types of lighting technology, including the sun, have their own frequency spectrum, with peaks at certain bandwidths. Unlike the sun (and other lighting technologies), fluorescent lights are not stable, but rather, they are pulsing, i.e. they go on and off several times per second. As technology evolved over time, the average refresh frequency increased from less than 100 Hertz (times per second) to several hundreds or thousands of Hertz. I know that many experts are claiming that we cannot perceive certain higher refresh rates, but when I consider that the sunlight does not go on and off all the time, but rather it is "always on", I can't avoid thinking that everything else is not as "natural". The negative effects of 100% fluorescent room lighting have been known and studied for some time, and thinking about it from this perspective I would find it logical that directly staring at a source of fluorescent light can be just as bad, if not worse. I know that many people have problems with the energy-efficient fluorescent room illumination in general, and prefer the traditional light bulb, which I believe has a wider frequency spectrum. The incandescent filament of a light bulb probably also generates a more stable light than the fluorescent substrate under the intermittent pulses of electrons. Assuming that fluorescent light is a bit like the scan lines of a television, i.e. it turns on and off all the time, but our eyes and nervous system make us perceive it as a persistent light, I cannot understand how some publications that praise LCD displays ignore this similarity with what is possibly the most negative aspect of CRT displays. Even if you don't normally perceive the flickering of your display or TV, if you point your eyes upwards, you may be able to discern some flickering in the lower part of the visual region (the peripheral area is more sensitive to flickering). I am sure that there is a range of frequencies, which may or may not include the refresh rates normally used for fluorescent light, which cannot be perceived by the average person, but which can cause discomfort in the longer term. Could it be that the fluorescent light is a factor or co-factor in this "LCD Syndrome"? And if so, is it because the spectral distribution of the light is not what evolution trained us to live with, or because a pulsating source of light is used for the background illumination, or for a combination of both reasons? I know people sensitive to fluorescent light, but also people sensitive to flickering in general (even to the way frames are displayed at movie theaters, which is considered relatively stable). Pixel Sharpness and Pixel Patterns LCD displays are better known for their brightness and for their "sharp pixels" than for the fluorescent light they employ. What if one of those very same factors which are normally considered positive in benchmarks, such as its crisp pixels, were part of the problem? On LCD displays the individual pixels are much sharper than on CRT displays, thereby making it possible for the eyes and the brain to: focus on each pixel recognize pixel patterns I believe that both factors could introduce new potential causes of discomfort, compared to CRT technology, considering that neither with CRTs nor in real life do we normally have as many tiny details to focus on with such clarity, and for those parts of the brain which discern movement and high contrast images to work on. Microsoft Windows includes a font smoothing technology called ClearType, which uses the colored sub-pixel components of LCD display pixels to increase the perceived resolution, while at the same time reducing the contrast and sharpness of the (larger) individual pixels. It can be enabled in the Appearance tab of the Display Properties, under Effects... Brightness What else is so nice about LCD displays, besides their crisp pixels? Brightness, of course. In my experience LCD displays have higher default brightness settings, and can reach an even higher level by adjusting the settings. A possible explanation for the high default settings may lie in a combination of technology and marketing. While CRT technology is limited in the maximum brightness that can be achieved (visible light is generated by the phosphor coating behind the glass when it is hit by an invisible beam of electrons), in LCD displays the rendering technology is separate from the light source, making it possible to use brighter sources of visible light. Since maximum brightness is often a parameter in monitor benchmarks, manufacturers are tempted to prefer (since it comes at a relatively low cost) high brightness technology in LCD displays. One piece of advice I can give in case of perceived problems in relation to LCD displays is, indeed, to try and reduce (even drastically) the brightness settings, as these displays can be, in my personal experience, much brighter than CRTs. I have seen this solving more than one problem case. Polarization Whereas sunlight and light emitted by incandescent bulbs and CRT displays oscillates in multiple directions perpendicular to the light beam, the fields from polarized light oscillate in only one direction. Polarized light is not only produced from certain light sources, but it can be the result of non-polarized light being reflected from certain surfaces (e.g. water or glass), or being filtered by polarized filters, which include certain sunglasses, liquid crystals, and the polarizer plastic sheets used in LCD displays. Several animals are able to detect light polarization. Some, like honeybees, use this sensitivity as an aid in their navigation. On LCD displays a combination of polarized filters and the ability to electrically control the polarization angle of liquid crystal molecules is used to produce images. Two side effects of this technology are that: the resulting light, as seen by the user, is polarized as the user's viewing angle changes, the visible image content changes too (more or less noticeably, depending on the display type) Binocular Cues Our sense of depth in viewing the real world is the result of several factors, which include the fact that each eye sees a slightly different view of the world. This is also used in stereoscopic (3D) visualization technologies, some of which have viewer discomfort as a well-known side effect. This may be caused by the inability to cope with excessive 3D cues, or by "wrong" cues altogether. If this is a factor affecting 3D display technologies, and considering that most LCD displays have a viewing angle limitation which results in slightly different images being received by each eye, there could in my opinion also be a relationship with LCD display discomfort. Update As of the end of 2001, i.e. after more than five years of additional experience since I first wrote this text, I keep getting a diversity of feedback from readers of this page, however I am now myself using the 1600x1200 pixel LCD display of my notebook computer (IBM ThinkPad A21p, pretty high resolution, I love it, but I know that other people are not at ease with the small pixels). I actually prefer the notebook display to the same resolution displayed by a top-of-the-line brand name 22" CRT set at a high refresh frequency. Although the LCD display is smaller, the pixels are much more detailed and crisper, resulting in the smaller display being much more readable than the larger one. This was, of course, also the case with the first LCD displays I tried more than five years ago, but something must have changed in the technology, as I can now work all day on an LCD display without discomfort. I am told that new electronic components result in higher refresh frequencies of the fluorescent light, however I don't know if this is a possible factor. It could also be that at a resolution of 1600x1200 my eyes are not trying to focus on the individual pixels as they had possibly been doing at 800x600. Also, one of the first things I did on this display was to reduce the brightness. Changing the surrounding lighting (e.g. adding a small light to reduce the perceived brightness of the display) has also been reported to help. Quite often LCD displays are sharper, but smaller, than CRT displays having the same resolution, so that old habits may result in the LCD panel being positioned too far away, which also can cause a type of discomfort not experienced with larger displays. I've heard of cases where even an additional keyboard placed in front of a notebook computer caused the notebook (and its LCD display) to be placed too far away to be comfortable, yet the cause of the discomfort was not immediately obvious. On the other hand, the closer the distance the more likely it is that the eyes recognize the individual pixels, which may or may not be related to the perceived problem. At this point I find it noteworthy how factors like the increased visibility of individual pixels and patterns of pixels (which phenomenon can be reduced, e.g. by using technologies such as ClearType or by using higher resolution displays), and the high brightness potential of LCD displays (which brightness can also easily be reduced by adjusting the monitor settings), lead to interesting parallels with the triggers and mechanisms which are related to headaches and other symptoms in a condition known as Scotopic Sensitivity Syndrome, or Irlen Syndrome. This topic is fairly well-researched (and in part commercialized, including patented aids and solutions), although I could not find it related so far to manifestations of LCD display discomfort. Conclusion It appears that LCD displays have introduced a new combination of elements which are not present in nature, possibly including issues such as spectral distribution, flickering, more recognizable pixels and patterns, increased brightness, polarization and "wrong" binocular cues. This is not what evolution has trained us to live with under the sun, and some people react to it differently than others. In particular, given a combination of these factors, some people appear to develop an "LCD Syndrome". I hope that this little research helps, at least to know that if you read this page up to this point, you are not alone. Feedback Here is some feedback kindly provided by other computer users who found this page: I was wondering if you've heard from anyone who is experiencing these headache/nausea symptoms after purchasing an LCD TV? I have recently purchased an expensive 50 inch LCD [...] TV and am finding it difficult to watch - about five to ten minutes in I start feeling headachy and nauseous. I love the screen resolution and find it to be a much better picture than other large screen TVs (other than plasma), but I'm afraid I have wasted my money. Has anyone given you advice in this area on how to relieve the LCD-induced strain? -- Hi, you cannot imagine how grateful I am to you for writing your online article about LCDs and Fluorescents. It was such a tremendous relief to read all those testimonials and thereby know that I'm not alone in my experiences. May I suggest a way to make your site Google-findable to a greater cross-section of people, by adding more keywords, such as: "EMFs, electromagnetic fields from monitors, electrosensitive to monitors, electrosensitivity issues" (remember, some people may be deluded by mass misguidedness, into thinking that theirs is an EMF problem versus a photosensitivity problem... -- I can't tell you how relieved I was to find your posting on your website about LCD problems. I experience those symptoms too of eye fatigue and headache within a few minutes of starting up my new iMac. It is actually more problematic than my [...] CRT monitor. I also have problems with fluorescent light boxes for film and flat panel light boxes. Quite a handicap since I am a photographer who wants to do more Photoshop. I keep looking for solutions, or scientific confirmation of what you and your respondents describe. -- I just wanted to say thank you. I found your article on LCD Displays and Fluorescent Light, I now realize it isn't just me and have told my boss I would like to go back to my old fashioned monitor. -- #1 lesson I have learned over the years.... The eye is not designed to stare at the brightest thing in the environment! (Nothing of interest is in the Cavemen's sky.) The solution? Always have something in your field of view as you work that is BRIGHTER than your screen. A small table lamp behind or directly above the screen works great at helping your eye adjust to the correct F-stop and prevents eye strain. Obviously old style fluorescent room lights should not be combined with computer monitors, because the two sources of flashing cause, to use the EE [electrical engineering] term "aliasing", other frequencies of flashing. I think the newer compact fluorescents flash faster and are less of a problem. So in my experience most eyestrain is correctable with a $10 table lamp. -- I stumbled across your page while looking for LCD information, and my experience is the opposite! I'm 20 years old, I cannot sit at a CRT monitor, usually including a TV, for more than a couple hours. The symptom are a bad headache and more fatigue than with an LCD. I view the CRT monitors at about the same location as I do LCD monitors. I don't think it is the refresh rate, but it could be. I usually have it set to a minimum of 75Hz, which is when I can barely see the flicker from the refresh (although, I can see it quite strongly out of the corner of my eye). I have the resolution the same as my LCD screen (1024x768) because that's the max of my LCD, and CRT's tend to get too blurry when you put them at any more than 1024x768 (comparatively). Right now, I only have a laptop, and I use it in all types of settings. Even when it is on my lap, I don't get a headache. -- Thank you for your article... I have been suffering from the above for a month and you have told me more than any doctor/optician/ophthalmologist. I must have spent about 20 hours searching the 'net for info... A month ago I started noticing the same symptoms as you: funny feeling in the eyes, slight headaches. The first day it took just 1 hour to recover. the second it took 3h. Then the whole night. Then the whole weekend. Then by the end of the week it would just take one hour in the office before I had to go home!! However in my case, I notice that I am now very much allergic to fluorescent lighting (I was not before...) I hadn't thought about the possibility that it could be my new LCD screen which has thrown me "over the edge" by exposing me to all this light... sounds very likely now. -- What a relief to read your article "LCD Displays and Fluorescent Light." I've been struggling with a brand new [...] 17" TFT LCD for four months now. I spent $1000Cdn trying to avoid eye strain and radiation and I've just ended up with some of the worst headaches of my life. I even went so far as to get the company to send a replacement and nothing has worked. It would make a lot of sense if the problem was some kind of inherent issue with the fluorescent lighting. -- I'm a computer engineer; I spend all day in front of my CRT monitor without a problem, year after year. I recently bought and returned several new CRT monitor because they had various focusing/convergence problems. I then bought a [LCD monitor], which is wonderful for its clarity and color saturation, but seems to be burning-out my eyes and causing low-grade headache, even when I reduce brightness to zero (as dim as I can make the display). This is disappointing. I don't think I can use this device. [...] The LCD image seems to be good to your retina and bad to the rest of your nervous system. -- I noticed irritation almost immediately, as you did, but tried to rationalize it as something else (sometimes if I each too much citrus, my contact lenses will irritate my eyes as tear mucus levels drop), but this irritation kept on building, and my eyes still bothered me a little when I woke up the next morning. Then I noticed that the eye irritation and headache would literally surge when I switched the screen to a mostly white image (like black text on white background). [...] There have been enough studies done confirming the bad physiological effects of fluorescent lights in classrooms and workplaces for us to infer that putting the same device behind an LCD shutter matrix one foot from your face it at least as bad as a fluorescent light overhead. -- My general vitality at day three is getting worse. The eye-ache will progress to headache, and then to a very slight, passing wave of nausea. I am defocused and disinterested in programming matter that I normally pursue with passion. [...] The problem is definitely white light. Whenever I flip to a screen with mostly white areas, the pain/tension/general disease/nausea will surge slightly. I fear that there is only so much I can do with this device. -- Fluorescent light seems to induce migraines. I'm in a shared office at work and when I can convince everyone to turn off the overhead lights I usually feel much better at the end of the day. I've been using computers for about 20 years now and it is getting harder and harder to use normal monitors. This sensitivity actually led me to Wilhelm Reich's research indicating that fluorescent light is very disruptive of ambient energy. James Demeo made a pretty impressive list of Masters thesis papers and doctoral dissertations dealing with Reich's theories... I think at least that something more than meets the eye is going on. I have a fairly new IBM ThinkPad at home which I like very much, but like the computer at work I cant spend too much time without getting up and walking around the apartment for a while... -- I found your discussion of LCD and fluorescent lights very helpful. I have never been able to use them successfully. My most recent attempt, on a truly lovely new Apple display, quickly led to vague eye discomfort and vague nausea. It wasn't going to work! -- Oh my god, you're so right! [...] Excited about all those "easy on the eyes" reviews about LCD displays, and frustrated from those flickery CRT monitors, I bought me a new and shiny LCD monitor. Ten minutes after I started using it, my eyes became "dizzy", accompanied with a little headache, and I could surely see the white background flickering like hell. I thought to myself : "what the hell? wasn't I supposed to get a relief for my soaring eyes by this new invention?" then I checked the web and I found your article about LCD Displays and Fluorescent Light. I almost cried when I realized what a waste of money this whole LCD shit is. I've put a lot of money buying this new screen and now I realize that it was for nothing, my eyes will continue to suffer, and there's nothing I can do about it. -- I've been suffering from debilitating chronic daily headaches for almost 2 years triggered by the [both CRT and LCD] computer monitor. My headaches get better after I stop looking at the screen for about half an hour. The days I don't use the computer at all I feel great. My headaches are also triggered by fluorescent lights. I tried a TFT LCD monitor, my headaches got better but I still got daily headaches. LCDs aren't supposed to flicker but I could sure see them flicker. -- Fluorescent is fluorescent is fluorescent. Whether or not it is overhead, actually, or behind a small screen (if the LCD screen is fluorescent-lit). [...] I'm somewhat rusty regarding the issue, but I will tell you what I remember. You are correct regarding natural, real sunlight. he spectrum is distributed fairly equally between the visible regions. UV is something like only 12% of the total. The rest is visible. The problem with fluorescent light is in order to make it bright (sorta like "sunlight") they must use a great deal of green and blue. "Full spectrum" uses a huge amount of visible blue. What it does is peak at an incredibly high level. I.e.: sunlight has approx level (I've forgotten the technical term, but if you need to know I'll dig it out of my file) at 225 of visible blue and fluorescent has over 1000 around the 435 nm level. The problem is, our eyes have developed to operate and see things visually at the range of 225 and fluorescent light over stimulates the eye to produce the same effect indoors. The retina of the eye is best stimulated by "blue." I have in my possession only a fraction of animal/insect research that proves visible blue damages the retina at a level that is not easily seen on routine eye examination. In the studies, if the exposure was short, then there would be repair by the eye. If the exposure is long-term, there is permanent damage. When I was trying to have the ophthalmologists read the research I'd gathered, they only say the animal research does not apply to humans. I don't believe them. -- The LCD screen I would imagine must not be much different from [handheld game with LCD display], would it? I did have a problem with those. -- I had a similar experience with a palm-size PC, which uses green LED (I believe) backlighting. It appears that in order to conserve battery power the light is pulsing on and off all the time, like the fluorescent light on notebooks. When the light is on I can hear a hissing sound on the speaker, which may be the frequency at which the LED is switched on and off. I find it disturbing to even play Solitaire when that light is on. Any comments or experience you would like to share are very appreciated. My email address appears on the main page. If you would like to provide feedback concerning a newly purchased LCD display, kindly also consider adding a few details such as: Did you place the LCD panel in the same position (e.g. on your desk) and lighting conditions (e.g. background) where you previously were using a traditional CRT monitor? Did you try adjusting the brightness of the LCD display and its position (distance) relative to you? What is the resolution of the LCD display, and what was the resolution of the previous CRT monitor you were using (if any)? What was your subjective experience with the LCD display and how was it different from that with other types of monitors? Thank you.