# Green eyshade purpose
**URL:** https://boards.straightdope.com/t/green-eyshade-purpose/292655
**Category:** Factual Questions
**Created:** [March 2, 2005, 9:50pm UTC](https://boards.straightdope.com/t/green-eyshade-purpose/292655 "2005-03-02T21:50:51Z")
**Posts on this page:** 8
**Page:** 1
### Author:  [@deadprogrammer](https://boards.straightdope.com/u/deadprogrammer)
#### Post date: [March 2, 2005, 9:50pm UTC](https://boards.straightdope.com/t/green-eyshade-purpose/292655/1 "2005-03-02T21:50:51Z")
What is the purpose of the green eyeshade that you see in pictures of old-timey editors, accountants and telegraph operators? If it is just to cut glare from overhead lights, why is it clear and why is it green?
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### Author:  [@Chairman\_Pow](https://boards.straightdope.com/u/Chairman_Pow)
#### Post date: [March 2, 2005, 11:42pm UTC](https://boards.straightdope.com/t/green-eyshade-purpose/292655/2 "2005-03-02T23:42:25Z")
Yep, it’s to cut the light. I imagine that they weren’t working under nice fluorescent lights, but rathare very harsh incandescents that had to be placed close to what they were working on, so the light would really distract them.
As to why it’s semi-transparent, my WAG is that if your head’s down you can look up and see if someone’s entered the room/check stuff that’s “up” without having to move your whole head and risk losing your place even further.
As for green, I have no idea.
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### Author:  [@spingears](https://boards.straightdope.com/u/spingears)
#### Post date: [March 3, 2005, 1:23am UTC](https://boards.straightdope.com/t/green-eyshade-purpose/292655/3 "2005-03-03T01:23:52Z")
> [@deadprogrammer](#):
>
> What is the purpose of the green eyeshade that you see in pictures of old-timey editors, accountants and telegraph operators? If it is just to cut glare from overhead lights, why is it clear and why is it green?
Green is a ‘cool’ color!
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### Author:  [@umop\_ap\_sdn](https://boards.straightdope.com/u/umop_ap_sdn)
#### Post date: [March 3, 2005, 3:15am UTC](https://boards.straightdope.com/t/green-eyshade-purpose/292655/4 "2005-03-03T03:15:08Z")
> [@Chairman Pow](#):
>
> As for green, I have no idea.
Green probably offers the best contrast between the eye’s sensitivity and the incandescent lights’ output. ISTR that the extreme periphery of the retina contains only rods, which are rather sensitive to green light.
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### Author:  [@Squink](https://boards.straightdope.com/u/Squink)
#### Post date: [March 3, 2005, 5:13am UTC](https://boards.straightdope.com/t/green-eyshade-purpose/292655/5 "2005-03-03T05:13:09Z")
> [@](#):
>
> telegraph operators?
Were these visors made of glass or colored mica in the days before [celluloid](http://en.wikipedia.org/wiki/Celluloid) (~1870)?
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### Author:  [@TV\_time](https://boards.straightdope.com/u/TV_time)
#### Post date: [March 3, 2005, 5:01pm UTC](https://boards.straightdope.com/t/green-eyshade-purpose/292655/6 "2005-03-03T17:01:51Z")
> [@umop ap!sdn](#):
>
> Green probably offers the best contrast between the eye’s sensitivity and the incandescent lights’ output. ISTR that the extreme periphery of the retina contains only rods, which are rather sensitive to green light.
I also believe it was the only color they came in.
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### Author:  [@wolf\_meister](https://boards.straightdope.com/u/wolf_meister)
#### Post date: [March 4, 2005, 1:54am UTC](https://boards.straightdope.com/t/green-eyshade-purpose/292655/7 "2005-03-04T01:54:14Z")
What about the same eyeshade for the archetypal gambler of the 1920’s & 1930’s? I have heard that a specially-marked deck could be “read” by the dealer (with eye shade) by having the green-tinted light fall on the backs of the playing cards as they are dealt.
I have heard this rumor. I don’t have a cite for it, but I believe some card cheats have done that. I also think this “trick” died out _long_ ago.
Cheating in gambling ? I am shocked !!! :eek:
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### Author:  [@Chairman\_Pow](https://boards.straightdope.com/u/Chairman_Pow)
#### Post date: [March 4, 2005, 2:58am UTC](https://boards.straightdope.com/t/green-eyshade-purpose/292655/8 "2005-03-04T02:58:53Z")
> [@wolf\_meister](#):
>
> What about the same eyeshade for the archetypal gambler of the 1920’s & 1930’s? I have heard that a specially-marked deck could be “read” by the dealer (with eye shade) by having the green-tinted light fall on the backs of the playing cards as they are dealt.
> I have heard this rumor. I don’t have a cite for it, but I believe some card cheats have done that.
Well, there were cards that had the suits/numbers written on them and by use of special glasses, one could read them. The idea was similar to the old Panini sticker books where a piece of red cellophane effectively disguises a red “scrambler” layer over an image, allowing the image to be seen only if the cellophane is used.
Scarne in his book on cards (can’t think of the title right now, probably _Scarne on Cards_ writes about them (book was published in the '50s IIRC) and basically said they weren’t worth a damn.