My brother has frequently claimed that prolonged exposure to UV light (or possibly a specific wavelength of it) turns your eyes blue. I don’t really believe it but he’s very insistant on the matter so I thought I’d seek your help in settling the matter.
Don’t look at UV light sources.
He’s thinking of melange in Frank Herbert’s Dune:
http://images.search.yahoo.com/images/view;_ylt=A0PDoS.9EWpPIyEAzseJzbkF;_ylu=X3oDMTBlMTQ4cGxyBHNlYwNzcgRzbGsDaW1n?back=http%3A%2F%2Fimages.search.yahoo.com%2Fsearch%2Fimages%3Fp%3Ddune%2Bmovie%26_adv_prop%3Dimage%26va%3Ddune%2Bmovie%26fr%3Dyfp-t-701%26tab%3Dorganic%26ri%3D118&w=800&h=445&imgurl=www.universalstudiosentertainment.com%2Fassets_c%2F2010%2F04%2F62031836_Dune_800x445-thumb-800x445-612.jpg&rurl=http%3A%2F%2Fwww.universalstudiosentertainment.com%2Fdune%2F&size=145+KB&name=Dune+on+DVD+%26amp%3B+Blu-ray+|+Trailers%2C+bonus+features%2C+cast+photos+%26amp%3B+more+...&p=dune+movie&oid=ea733ce1dfb30e6c0b8bbaf73fc95975&fr2=&fr=yfp-t-701&tt=Dune%2Bon%2BDVD%2B%2526amp%253B%2BBlu-ray%2B%257C%2BTrailers%252C%2Bbonus%2Bfeatures%252C%2Bcast%2Bphotos%2B%2526amp%253B%2Bmore%2B...&b=91&ni=180&no=118&tab=organic&ts=&sigr=11iaq1ohg&sigb=13nf0ggqi&sigi=132fqkbgk&.crumb=G.kSrW0OssH
Also, what erislover said.
Many things look odd under UV because of fluorescence. Bleached cotton is bright white/purple. Tonic water glows blue. Teeth and sometime eye-whites look oddly brown/orange. Coca-Cola looks a sick green.
But it’s only while the light is on, not a permanent change. UV can bleach things or cause permanent color changes (as with Color Centers in crystals), but I doon’t think the sclera of your eye is one of them.
He’s not, I checked. Honestly I have no clue as to where he got this idea from, although he does claim that explorers of polar regions end up with blue eyes from the light reflecting off the snow (something I’m 99.99% sure is B.S.) and that our dentist has really blue eyes because of the light they use (said dentist does have blue eyes of a rather unusual shade but I’m pretty sure he’s always had them). On the other hand, I just asked him again and he said that it might not be UV but that it’s still something to do with light. I still don’t believe it.
I haven’t heard of such a thing actually being done, but since blue is the “default” color, I could see the lasers that erase tattoo pigments being potentially repurposed to disintegrate the molecules that cover up the blueness in other color eyes.
Default color?
I believe people with blue (or lighter colored eyes) tend to be more susceptible to UV damage. Maybe that is part of his memory/reasoning?
I don’t think so. I asked him about again and as usual he was utterly convinced that the right sort of light would turn your eyes blue and claimed to have seen an Arctic explorer who started out with brown eyes and ended up with blue ones due to the light reflecting off the snow.
But, people living in dry the tropics are exposed to far more UV than arctic explorers.
So by this logic all those people living in Australia and the the Northern and Southern parts of Africa must have blue eyes. Does that seem reasonable to you?
Yep. But apparently I was wrong in saying that it was UV that did it and it is in fact the glare off the snow and/or the change of eye colour is a symptom/lasting reminder of snow blindness. I still don’t believe it but he seems pretty convinced about this.
So that’s the explanation for all those blue-eyed Eskimos/Inuit/etc.! Except there aren’t any blue-eyed Eskimos/Inuit/etc.*
Perhaps he read something like the following and then mixed up light/eyes and prevention/cause:
(from here) “If you are trying to prevent snow blindness, then you need to choose sunglasses that are specifically designed to block blue light.”
*Isolated counterexamples not necessary, you know what my point is. 
Could he have read something about rhodopsin a.k.a. visual purple, a purplish pigment that forms in the retina of the eyes in low-light conditions to assist with low-light vision?
(If so, of course, your brother has the facts thoroughly garbled because this doesn’t sound at all like what he’s claiming.)
ETA: Okay, FINALLY got that link right!
[quote=“Gary_T, post:10, topic:616426”]
So that’s the explanation for all those blue-eyed Eskimos/Inuit/etc.! Except there aren’t any blue-eyed Eskimos/Inuit/etc.*/QUOTE]
I did point that out to him. He didn’t really have a good explaination, just something about them being adapted to their environment (the way he phrased it makes me think that he’s got some odd ideas as to how evolution works too). He still solidly maintains he’s right though. sigh
He might be thinking stronger forms of radiation. There was one worker at Chernobyl who got such a heavy dose that his eyes went from brown to blue in the time before his death, because they stopped producing pigment. He kept going back in so they wouldn’t send a replacement, rather than stay at the hospital.
The reason babies have blue eyes is that they haven’t started producing the iris pigments yet.
Is your brother a fan of Avatar: The Last Airbender ?
Exposure to UV light has no permanent effect on eye color. Eye color is determined by genetics, and is indicative of the levels of melanin contained within the iris. Eye color is known to change, for some people, in early childhood (generally from blue to brown). But after age 3, it is a very rare occurrence. For example, my younger cousin had blue eyes when he was born, but they turned brown when he was 1. And they’ll be brown forever, barring some very rare circumstances. Eye color CAN change later in life, but only as a result of physical trauma or hormonal causes (puberty/pregnancy).
Some facts: The spectrum of eye color (from least to most melanin) is: red, violet, blue, green, brown, black. Only people with severe albinism (who produce no/almost no melanin and are very pale with white hair) have red eyes. Only 2.2% of people worldwide have blue eyes. And as people of different races continue reproducing together, that number is decreasing because blue eyes 1) are recessive and 2) were the result of a genetic mutation.
I’m not sure *why *you keep insisting that he’s so convinced about this, as though his conviction has any effect on biological fact. He’s wrong, and very stubborn about it. You’ve already provided him with counterexamples (like the lack of blue-eyed Inuits) and he keeps changing his story, although he won’t change his mind. This is known as “moving the goalposts.” He won’t admit he’s wrong, no matter how much evidence you throw at him. I suggest you stop wasting your energy on his arguments. He’s either fucking with you, or he’s hopelessly intellectually incurious.
That’s interesting. I guess if some form of radiation could erase pigment they’d eventually go past blue and turn red.
Definitely with cases like the Chernobyl guy that’s a possibility, it seems like the only reason they didn’t was he didn’t live long enough.
<physics nitpick>
It definitely is something to do with light! The color of his eyes is determined by which wavelengths of visible light his irises reflect.
</physics nitpick>
The only time I’ve heard of something similar was on an episode of the popular TV science documentary series, Doctor Who, entitled “The Horror of Fang Rock”. In that, Leela’s eyes were changed from brown to blue by the the intense light of an explosion caused by a high-powered laser.
Although I think Crystal Gale may have had something to say on the subject, too.
Indeed. This being GQ, the answer is “he’s wrong”. It doesn’t happen. The end. If you want to know why he believes this, that’s another thread. I don’t know that anyone here can offer anything beyond “he’s wrong” that will be of any use.