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Well I’ve been calling LED light , Dirty Light for years . No one listens to me though lol .
Btw, I use blue blockers when I’m using my iPad , flat screen tv and computer etc.


They claim there’s no UV , and there wrong in the worst possible way . There is hardly any UV output from UVA(315-400 nm) , but at UVC (200-285 nm) which is known as an eye irritant and used to purify water , there’s as much output as its excessive blue output .

MIT has actually retooled the incandescent light , so it actually has a better efficiency than led lighting. But politicians have deemed incandescent illegal to use , so they can’t mass produce it
 

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I have a hard time looking at my iPad after getting used to wearing blue blocker glasses .
You realize just how horrible the bluish white is after using the proper glasses .
 

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All my LEDs are lower on the kelin scale. This should greatly reduce or completely eliminate the UV radiation. Kelvin is directly related to the wavelength of the light, at least as I understand. You can put blue filters over a low Kelvin light, but it doesn't add any more uv to the output. Nearly all my LED lighting is 2800 Kelvin, withone or two leftover, lower lumen 4,000 K lamps.

Summary from a more technical site on LED levels.

"Both cool and warm white LEDs can be built from blue LEDs + luminescent material or UV LEDs + luminescent material.

Those made from blue LEDs are in the far majority because they are much cheaper. Their UV emission is zero. The problem with these is the luminescent material is aging and so they are getting bluer with time, because a higher fraction of the light is passing the luminescent material unaltered.

Those made from UV LEDs don't have that aging problem because all light passing the luminescent material unaltered is invisible. They are only getting darker with time. So, yes, these LEDs do emit UV. And they are not cheaper but more pricey because of their better color stability over time.

BUT, in a light bulb there is a glass in front of the LEDs. And ordinary glass filters UV nearly perfectly. (You can't get a suntan behind a window.) That's the same as for CFLs. If you need the UV, e.g. in a solarium lamp, the CFLs or LEDs need to use quartz glass or a transparent plastic for the casing."

https://electronics.stackexchange.com/questions/290187/do-cool-white-leds-emit-uv-light

The author recommends using only higher quality Phillips and CREE LED bulbs, which do use the blue emmitting diodes, but with a coating over them to absorb the blue. The higher quality bulbs have a longer lasting coating, and if they're glass encased, there isn't any significant UV output. You would need a color temperature meter to assess the presence of UV light, and not all CT meters will detect UV.

Blue light has gotten a lot of attention in the world of vision care. This is blue light, far below the UV range where the energy levels that strike the clear tissues of the cornea and the brain tissue that makes up the key layers of the retina. But blue light is associated with sleeplessness, and lowered blinking rate, which means dry, aching eyes. Air conditioning and heating also drys out eyes, so I'd be careful about blaming the UV, since it is very far above the blue spectrum. This would be particularly important if you are exposed for many hours to bluish LED light.

I have very little visual fatigue from lights, but using a computer drastically reduces blink rate, which drys out the oil component of tears, which is what is supposed to keep the eyeball moist. The oil comes from tiny glands along the edge of the eyelid. As people age, these glands attract a tiny parasite that takes some effort to get rid of, and that is present in nearly all people in their 60s and 70s. They're called Dermodex and here's a definition: "Demodex is a genus of tiny mites that live in or near hair follicles of mammals. Around 65 species of Demodex are known. Two species live on humans: Demodex folliculorum and Demodex brevis, both frequently referred to as eyelash mites." --Wikipedia

Treating dermodex is done using a very dilute solution of Tea Tree oil. DO NOT MAKE YOUR OWN!!!, get a commercial product from your optometrist or ophthalmologist. Here's a video, and then a picture of these mites. Before you blame UV, check for these tiny mites. In the video, some of the debris is Dermodex poop.

 

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Discussion Starter #7
Mine are Warm White fluorescent...can't remember what the actual colour temp is, but I like the 'warm' light they emit.
 

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Kelvin is a temperature scale that has zero set at absolute zero, i.e. the temperature at which all molecular activity stops. Without looking up the conversions about -470F and about -264C. The hotter the temperature, the bluer the glow. A percentage of incandescent is infrared which isn't visible.
 

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Tom , no matter Kelvin you purchace , the actual graphs showing the output of the colour range is horrible .
The majority of the light they emit is blue, and very little red
 

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Tom , no matter Kelvin you purchace , the actual graphs showing the output of the colour range is horrible .
The majority of the light they emit is blue, and very little red
One person's response to light can be far different than anothers'. I just wanted to post other possible problems misidentified as eyestrain. Here's a spectrum comparison of a 2800 K LED with daylight. If you have glass bulbs or coated bulbs, or wear glasses, the UV is filtered out. Older LED bulbs did leak UV, more and more as they age, but more modern ones have a coating on the LEDs that lasts far longer to block the UV. I don't react to the warm ones in any negative way, but that doesn't mean someone else won't react badly.

There is a branch of vision care that deals with use of spectra of light and how it impacts the brain and the person. So there's no question that color of light can be significant. Actually, color is really about electromagnetic emissions at specific wave lengths, long described as reddish, short as bluish. It is the wave front striking tissues that does damage or triggers reactions.

I have a bunch of old incandescent bulbs purchased for use rather than the curly bulbs, which flickered noticeably to me. Anywhy, here's a picture of the spectrum for a 2800 K LED:
 

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Discussion Starter #11
On a Clear Day You Can See Forever

Here's my 'take-home'; I'll need new prescriptions after my cataract surgeries. If it costs me an extra couple of hundred to get more retinal protection I figure it's money well spent. Can't replace them!
:nerd:
 

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Take the time to read that first link I posted. The mechanism whereby the retina is damaged is what's new in research.
"Karunarathne introduced retinal molecules to other cell types in the body, such as cancer cells, heart cells and neurons. When exposed to blue light, these cell types died as a result of the combination with retinal. Blue light alone or retinal without blue light had no effect on cells.

"No activity is sparked with green, yellow or red light," Karunarathne said. "The retinal-generated toxicity by blue light is universal. It can kill any cell type."

Read more at: https://phys.org/news/2018-08-chemists-blue.html#jCp
Pretty sure it's the presence of any amount of blue wavelength light that's crucial...UV is a whole 'nuther problem in this particular research.
 

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For those that wear glasses, Costco offers a coating which blocks the harmful blue light rays and supposedly allows the beneficial blue light to pass through. Interestingly, they claim it is effective against digital devices, screens and the sun but no mention is made of LED lighting.
 

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Discussion Starter #16
Well, I had my Left eye done this morning. I had e-mailed that Blue light~retinal link to my ophthalmologist; we had a quick chat about it (he hadn't previously seen it) and he told me that the lens he uses in cataract surgery already have blue blocker/UV filtration included! Colour me happy!!
He was using these slightly tinted lens for an entirely different reason but now he's pretty pleased that his choice is supported by scientific proof.
https://www.myalcon.com/products/surgical/acrysof-iq-iol/monofocal-iol-specifications.shtml
 

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Discussion Starter #17
Just out of curiosity, what does cataract surgery cost in the US? Say both eyes, done separately.
 

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A lot of cataract surgery is done on older people and medicare should cover it (may depend a little on the medical provider selected. If you have it done and pay privately the range is somewere between $300 - $600 per eye. There's a lot of price competition for that small group of private pay patients. Most surgeons do this surgery one eye at a time, and it takes 4-6 minutes, max. The only meaningful hazard is the emulsifier (like a tiny untrasound jackhammer), which will blow out the iris if it touches the iris. A blown iris disallows light regulation.

I worked with an MD long ago who developed an instrument that allowed him to eliminate most astigmatism by the placement and amount of tightening on a "flap" they cut to get inside the eye. I really liked him, probably dead by now. Don't know if that's still being done. Very clever.

Finally, the measurment of the size of the eye is critical in selecting the lens power to implant. One mm represents 3 diopters of error, so it doesn't take much of an error to have the patient wind up needing a strong Rx to compensate for the error. I'm 75 and haven't needed to have cataract surgery, but if I did, I wouldn't let the condition get to what is considered the minimum vision before doing the surgery.

And you can get all the coatings mentioned on almost any pair. What really makes a difference, however, is getting a top quality, "digital" progressive lens. The variable power replaces the focusing range you lose when your natural lens is removed. The digital lens is ground (or molded) to eliminate distortion in the peripheral areas of the lens. Much more comfortable than the cheaper and older progressive lenses. Contact lens bifocals don't work the same way as a spectacle lens, so if you are used to seeing sharply without noticable peripheral blur, a pair of glasses are your best bet.

Don't look for the low priced lens after cataract surgery!!!! :nerd:
 

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Discussion Starter #19
Good to know; thanks, Tom.
I was just curious. The total cost is covered by our Provincial Medical Insurance, except for the after surgery meds.
 
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