Blue hazard: LED lighting may compromise your vision and health

[conk]

Posted by onawah (here)
This subject comes up periodically on Avalon.
When it does, I always recommend Full Spectrum light bulbs which I've been buying from Dr. Mercola's website for several years now and really like them.

I can attest to the quality and longevity of these bulbs. We have around 8 to 10 of these bulbs and they have worked for many years.

Another source of poor light, blue light, is from smart phones and TVs. There are good tools to use with phones that cut out most of the blue light. It's said that blue damages the retina and greatly hinders proper sleep if used within an hour or so before bedtime.

[onawah]

From Dr. Mercola's article which I posted on the first page of this thread:
How to Make Digital Screens Healthier

Source: https://youtube.com/watch?v=HN30fO2I2aU

When it comes to computer screens, it is important to reduce the correlated color temperature down to 2,700 K — even during the day, not just at night. It’s even better to set it below 2000K or even 1000K. Many use f.lux to do this, but I have a great surprise for you as I have found a FAR better alternative that was created by Daniel Georgiev, a 22-year-old Bulgarian programmer that Ben Greenfield introduced to me.

He was using F.lux but became frustrated with the controls. He attempted to contact the F.lux programmers but they never got back to him, so he created a massively superior alternative called Iris. It is free, but you'll want to pay the $2 and reward him with the donation. You can purchase the $2 Iris mini software here.

Iris is better because it has three levels of blue blocking below f.lux: dim incandescent, candle and ember. I have been using ember after sunset and measured the spectrum and it blocked nearly all light below 550 nm, which is spectacular, as you can see in the image below when I measured it on my monitor in the ember setting. When I measured the f.lux at its lowest setting of incandescent it showed loads of blue light coming through, as you can clearly see in the second image below.

So, if you are serious about protecting your vision you will abandon f.lux software and switch to Iris. I have been using it for about three months now, and even though I have very good vision at the age of 62 and don't require reading glasses, my visual acuity seems to have dramatically increased. I believe this is because I am not exposing my retina to the damaging effects of blue light after sunset.

Iris Software:


F.lux Software:


Download it here: https://iristech.co/

Posted by conk (here)

Another source of poor light, blue light, is from smart phones and TVs. There are good tools to use with phones that cut out most of the blue light. It's said that blue damages the retina and greatly hinders proper sleep if used within an hour or so before bedtime.

[Cara]

[Franny]

I've been using F.lux for years but Iris does look like a better choice. Thanks!

[Cara]

This very comprehensive presentation on all things to do with light's effects on biological organisms is included in the article cited in the OP of this thread.

It's full of useful information about biological mechanisms affected by and influenced by light. It includes the history of the study of this area which is fascinating.


Source: Watch on Vimeo

[XelNaga]

My personal observation is that LED light bulbs are negatively effecting my eyes. If I spend a lot of time in room with LED bulb, my vision becomes a bit blurry and I feel a great strain on my eyes, which does not happen to me with regular bulbs

[Cara]

Posted by XelNaga (here)
My personal observation is that LED light bulbs are negatively effecting my eyes. If I spend a lot of time in room with LED bulb, my vision becomes a bit blurry and I feel a great strain on my eyes, which does not happen to me with regular bulbs

I am experiencing some eye problems with screens.

So, I've been doing some research into screens trying to find out more information. It seems that LCD (liquid crystal displays) have LEDs running behind a layer of crystals. I found this post describing the mechanics of LED and LECD screens on an optical forum:

What makes LEDs so efficient is they emit a very specific wavelength with a sharp rise and drop in the spectrum both before and after that specific wavelength. This means if you have a RED LED the light emitted will be in the red wavelength with very little infrared and very little orange light being emitted.

LED TV's use tricolor LED's consisting of a red green and blue channel, the combination of these colors can be used to create other colors so a pixel or LED can have any color but the makeup will be a combination of the active states of LEDs that comprise that particular color. For purple Red = Active, Green = Inactive, and Blue = Active. This is the makeup of the color purple. To control the intensity or different shades of the color purple the different diodes will be activated to different intensities so a light purple might have Red = 50% * Active, Green = Inactive, and Blue = 50% * Active which would give the same purple but dimmer. Since all LED model TV's are digital devices and digital is controlled by on off states of 1's and 0's to get the intensity to 0.5 or 50% is not directly possible digitally. That's where a microchip and crystal comes into play, the crystal or resonator creates a sort of on off cycle by resonating at a specific frequency measures in hertz (fractions of a time interval, seconds). Lets say for simplicity the crystal is 2 hertz (purely theoretical for this example) then the LED being wired to this crystal will cycle twice per second, which means in a second you could turn it on for 1/2 a second and turn it off for 1/2 a second. In essence now you have created a scenario where the state can be on for 50% of a second, creating the illusion of a half dim bulb, in reality the bulb is light full on for 1/2 a second and full off for 1/2 a second. The human eye has a thing called persistence of vision, think of a flip book where the same image is presented slightly different on each page of a book by flipping through the pages of the book you can attain the effect of motion. The brain perceives a dimmer bulb by flicking the LED on and off fast enough that the bulb looks dim, which allows a digital processor to control the working of the TV. That very same persistence of vision is why a 120hz TV is better for movies or sports that have a lot of motion since the refresh rate of the entire image on the TV screen is redrawn more times in that second, going back to our flip book example the pages are flipped faster so the animation looks smooth rather than jerky.

That's the background, now the backlighting that was mentioned in a previous post will give you a better idea of the amount of blue light being emitted. A backlight is going to be on while the TV is on and it effects the entire screen. Overlaid on the backlight is crossed polarized filters with a liquid crystal layer between the crossed polarized layers. The liquid crystal layer controls the absorption of the backlighting and the rays that make it through the first polarized layer are polarized in one direction (assume vertically for a minute) that vertically polarized light then passes through the liquid crystal layer and depending on it's states changes polarized orientation slightly (this of the LC layer as a wave retarder) as the phase is changed these rays must then pass through the second polarized layer before reaching the watchers eye. If the LC layer does not change the phase of the light then depending on the efficiency of the polarized layers (100% efficiency is assumed) no light passes through since the light will not go through a crossed polarized set of filters that are 100% efficient. If the phase is changed 90 degrees then all of the light passes through, so the eye sees the backlight color. For simplicity backlights are white so the crossed polar states means you see black at that point of no light escapes, 90 degree phase change means you see white.

With this background knowledge you can make some guesses as to the effects of LED vs LCD. Depending on the efficiency of the polarized filters LCD TV's are going to emit more light (assuming less that 100% polarized efficiency which is reality). Since white light is composed of the various wavelengths then yes more blue light is going to get out but that does not necessarily mean that more blue light is emitted from a LCD TV vs an LED TV. A whole lot is going to ride on the quality of the components used in both models. Go to your local TV outlet and look at a number of TV's with the same parameters and you will notice some screens are more dimly light then others. Plus the components inside like resistors that are often used to limit the current going through an LED or backlight have tolerances with the loosest being 10% variation and the best being used to power critical applications less than 1% (good luck finding one in any TV set), meaning even in the same exact model you will get some range.

To summarize all that "who cares" they are roughly equivalent given that one creates the specific colors and the other creates white and subtracts away the wavelengths not used. In essence unless you measure the intensity of light or brightness of the screen all the theoretical nonsense is just nonsense.

From: https://www.optiboard.com/forums/sho...-Transmittance

And here is some explanation of the terminology used in describing LCD screens, which I found helpful:

To evaluate the specifications of LCD monitors, here are a few more things you need to know.

Native Resolution
Unlike CRT monitors, LCD monitors display information well at only the resolution they are designed for, which is known as the native resolution. Digital displays address each individual pixel using a fixed matrix of horizontal and vertical dots. If you change the resolution settings, the LCD scales the image and the quality suffers. Native resolutions are typically:17 inch = 1024x76819 inch = 1280x102420 inch = 1600x1200

Viewing Angle
When you look at an LCD monitor from an angle, the image can look dimmer or even disappear. Colors can also be misrepresented. To compensate for this problem, LCD monitor makers have designed wider viewing angles. (Do not confuse this with a widescreen display, which means the display is physically wider.) Manufacturers give a measure of viewing angle in degrees (a greater number of degrees is better). In general, look for between 120 and 170 degrees. Because manufacturers measure viewing angles differently, the best way to evaluate it is to test the display yourself. Check the angle from the top and bottom as well as the sides, bearing in mind how you will typically use the display.

Brightness or Luminance
This is a measurement of the amount of light the LCD monitor produces. It is given in nits or one candelas per square meter (cd/m2). One nit is equal to on cd/m2. Typical brightness ratings range from 250 to 350 cd/m2 for monitors that perform general-purpose tasks. For displaying movies, a brighter luminance rating such as 500 cd/m2 is desirable.

Contrast Ratio
The contrast ratio rates the degree of difference of an LCD monitor's ability to produce bright whites and the dark blacks. The figure is usually expressed as a ratio, for example, 500:1. Typically, contrast ratios range from 450:1 to 600:1, and they can be rated as high as 1000:1. Ratios more than 600:1, however, provide little improvement over lower ratios.

Response Rate
The response rate indicates how fast the monitor's pixels can change colors. Faster is better because it reduces the ghosting effect when an image moves, leaving a faint trial in such applications as videos or games.

Adjustability
Unlike CRT monitors, LCD monitors have much more flexibility for positioning the screen the way you want it. LCD monitors can swivel, tilt up and down, and even rotate from landscape (with the horizontal plane longer than the vertical plane) to portrait mode (with the vertical plane longer than the horizontal plane). In addition, because they are lightweight and thin, most LCD monitors have built-in brackets for wall or arm mounting.Besides the basic features, some LCD monitors have other conveniences such as integrated speakers, built-in Universal Serial Bus (USB) ports and anti-theft locks.

LCD TERMS

• Bezel - This is the metal or plastic frame surrounding the display screen. On LCD displays, the bezel is typically very narrow.
• Contrast ratio - The difference in light intensity between white and black on an LCD display is called contrast ratio. The higher the contrast ratio, the easier it is to see details.
• Ghosting - An effect of slower response times that cause blurring of images on an LCD monitor, it's also known as latency. The effect is caused by voltage temporarily leaking from energized elements to neighboring, non-energized elements on the display.
• Luminance - Also known as brightness, it is the level of light emitted by an LCD display. Luminance is measured in nits or candelas per square meter (cd/m2). One nit is equal to one cd/m2.
• Native resolution - This actual measurement of an LCD display, in pixels, is given in horizontal by vertical order.
• Response time - The speed at which the monitor's pixels can change colors is called response time. It is measured in milliseconds (ms).
• Stuck pixels - A pixel that is stuck either 'on' or 'off', meaning that it is always illuminated, unlit, or stuck on one color regardless of the image the LCD monitor displays can also be called a dead pixel.
• VESA mount - With this, you can mount a monitor on a desk or wall. It meets recommendations of the Video Electronics Standards Association (VESA).
• Viewing angle - It's the degree of angle at which you can view the screen from the sides (horizontal angle) and top/bottom (vertical angle) and continue to see clearly defined images and accurate colors.

From: https://computer.howstuffworks.com/monitor6.htm

[Bill Ryan]

This may or may not be helpful or relevant! But I stumbled on an interesting connection between outdoor sunglasses and indoor blue-blocking glasses to help protect eyes from damage when spending a lot of time in front of computer screens.

Quite a bit here, but I'll condense it as best I can. Bear with me!

1) Blue-blocking glasses.

Blueish light (which LED bulbs and screens emit) is stressful for eyes. Natural sunlight contains a lot more towards the red end of the visible spectrum, which supports eye health.

The remedy is blue-blocking glasses. Like these.

• https://amazon.com/gp/product/B000USRG90
  
  

They just have a plastic orange lens, and cost about $10. Couldn't be simpler.

2) Sunglasses. (The right kind!)

A personal story. Some of you may have read, or remember, that I injured my eyes back in January on a really extreme UV (ultraviolet) day, very high on a mountain, without any sunglasses. OMG.

I fried my eyes completely, and had to sit in the dark for several days to recover. But even after that, I was very sensitive.

I bought two kinds of high-tech sunglasses, from Julbo.

These seemed to be the best. 100% UV protection, and a Spectron 4 lens that cut out 95% of visible light. (They're very dark!)



But then I also got these, with a Spectron 3 lens, also with 100% UV protection, but which 'only' cut out 90% of the light.



The Spectron 4 lens is clearly darker. So the next three days I went to the mountains, even though it was dull and rainy each time, I wore those 'best' ones. And each time, my eyes were sore at the end of the day.

I was thinking "OMG, I've really damaged my eyes." I was pretty unhappy about that.

Then, the fourth day, a short time later, it was really bright and sunny. FAR brighter than the previous 3 days which had left my eyes hurting. I really wanted to go out, but this time I brought everything with me.

The Spectron 4s, the Spectron 3s, and also some huge anti-UV goggles which would actually fit OVER the glasses as a double layer if need be. I resolved to experiment and find some way that would protect me, at least maybe a little bit better.

Well, what I found was that my eyes were REALLY comfortable in the Spectron 3s. And at the end of the very long, bright day, 6 hours in the bright sun, my eyes weren't sore at all.

Yet the Spectron3s didn't cut out as much light as the 'better', darker pair. It seemed to make no sense — though I now knew what to wear from here on out.

Eventually, I realized what was happening. It was the COLOR of the lenses. The Spectron 3s were brown — and so they cut out the blue light but allowed in the red light. Simply that was what made the BIG difference.

Both blocked 100% of the UV. But after that, it wasn't the intensity of the light that mattered. It was the color.

See how that all fits together? But I've not read about that anywhere else... the importance of sunglass lens color.

It was only because my eyes were recovering from injury, and were very sensitive, that I could figure out what was was happening. Most people wouldn't notice the difference... though their eyes might still be gradually becoming more and more damaged in very bright light with the wrong color lenses.