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LCD Syndrome aka Computer Vision Syndrome


Dr.DK

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Hi,

I've been using TFT's for several years now and I loved them in the beginning but it looks like I'm becoming sensitive to fluorescent light.

Areas of the same color look very unstable, but detailed photos or videos are easy on the eyes.

I found a nice article that covers this discomfort:

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".

Read more:

http://cloanto.com/users/mcb/19960719lcd.html

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doubt it has to do with the monitors itself. many people see "optics". they just dont realise them until they have a trigger experience because their brain is so used to it. To give an example: Some people see pure black when they close their eyes but many others see flickering patterns, colors, moving shapes, "starfields" etc. Thats absolutely normal. Seeing colored "noise", flickering, after images etc. with open eyes is also absolutely normal.

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I think this is just uninformed and outdated scaremongering. I would think that if there is an effect it is very uncommon and if there is any link to LCDs it is probably difficult to substantiate, which is why you don't see any real scientific articles on the subject.

A quick look over the wikipedia article for fluorescent light shows this:

Fluorescent lamps which operate directly from mains frequency AC will flicker at twice the mains frequency, since the power being delivered to the lamp will drop to zero twice per cycle. This means that the light will flicker at the rate of 120 times per second (Hz) in countries which use 60-cycle (60 Hz) AC, and 100 times per second in those which use 50 Hz. This same principle applies to the occasional hum one hears from fluorescent lamps, which is primarily caused by the ballast. Both the annoying hum and flicker are eliminated in lamps which use a high-frequency electronic ballast, such as the increasingly popular compact fluorescent bulb.

Although most people cannot directly see 120 Hz flicker, some people report that 120 Hz flicker causes eyestrain and headache. Dr. J. Veitch has found that people have better reading performance using high-frequency (20-60 kHz) electronic ballasts than magnetic ballasts (120 Hz)

LCD backlights are usually cold cathode fluorescent lamps which operate very differently from your standard overhead lamps at much higher frequencies and do not "flicker". He doesn't directly mention CCFLs in his article, but in passing he dismisses his own concerns as fixed by "newer technology". He's even using LCDs himself:

however I am now myself using the 1600x1200 pixel LCD display of my notebook computer... 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.
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Not exactly sure if i understand what this is about, but i first noticed i could see "stuff" moving on my monitor while browsing mapcore forums (its just some white noise). I dont see it now, but ive seen it a few times. Im probably talking about something else ;)

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I guess the age and the way your brains works matters. This flickering and moving stuff* seem to happen to me only with flat bright smooth surfaces. Detailed surfaces, virtual or in nature, are always easy on the eyes. The brightness and color temperature also seem to matter because many people, including me, find it e.g. more comfortable to read from paper then from a computer screen.

* = I'm not talking about the "hello internets" snowflakes!

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When I'm tired and my eyes are "tired" I can see some colors "moving" when I'm watching a paper with fine texture grain in it, like a green 160mg watercolor paper.

But the doctor said that it is common when tired, the eyes react to light differently.

Other than that, I got 20/20 vision. And no anykind of color blindness.

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Flat bright areas do appear to me with slight artifacts such as moving colours, and such random stuff. Nothing which has ever bothered me though.

Btw. what are your screen settings? I got my CRT at this:

Brightness: 60/100

Contrast 100/100

Having a relative low brightness allows me to have darker surroundings without the screen getting over-bright.

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I wonder whether optical illusion plays a part. I mean, you're looking at thousands of dots, that's gotta do some funky stuff with your brains.

Btw. what are your screen settings?

It's hard to compare brightness, unless you have a hardware monitor calibrator. It can measure the brightness/luminance.

I'm running at 100 cd/m2, 6500 Kelvin color temperature and 2,2 gamma. 100~120 cd/m2 is about the maximum a CRT monitor can come up with.

Most modern TFT monitors have a luminance of 250~500 cd/m2! I even had to reduce the brightness of my graphics card to achieve CRT standards.

Too bad the brightness is being used in marketing. Manufacturers know that people drool at high specs but in this case it's just plain silly.

Who wants to look at stadium lights?

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Also bright monitor that shows several spinning red squares on a green background compared to a bright monitor with soothing pastel colors is very different.

My work setup is color calibrated monitors in a room with day light fluorescent lights. Home, it's just standard CRT monitor and a energy saver lamp, the difference is notieable.

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