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Author Topic: Rainbow in my left eye  (Read 1784 times)

Offline Taelia

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Rainbow in my left eye
« on: 02/11/2013 17:30:29 »
Hello,
I just stumbled across this site, and remembered a question I had as a kid; I never found an answer.

Back then, before my eyes were lasered, my eyes had -7.75, -7.25 strength. (Dutch measurements, I think america uses something different.)
I had lenses, and when I put in my lenses, with my left eye I saw the spectrum of any dot-shaped lightsource. In the form of a rainbow, a circle around the dot, and I could clearly separate the colors. (It was pretty awesome.)


I figured my lens bent the light and separated them, being a round surface and all, but I've never  been able to figure out why it only happened with my left eye. It didn't matter if I switched my left and right lens, still only happened with my left eye, and it only happened with that one, particular batch of lenses, I've never had it happen before or after that set again.

Surely, its been 10 years ago, maybe I'm remembering things wrong. But if anyone here has a better solution for me, I'd love to solve this little mystery of mine.


 

Offline RD

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Re: Rainbow in my left eye
« Reply #1 on: 02/11/2013 18:41:20 »
Back then, before my eyes were lasered, my eyes had -7.75, -7.25 strength.

7 dioptre is a strong prescription, the lenses would have to be unusually curved to correct that.
The more curved a lens is the more pronounced the chromatic aberration



I had lenses, and when I put in my lenses, with my left eye I saw the spectrum of any dot-shaped lightsource. In the form of a rainbow, a circle around the dot, and I could clearly separate the colors. (It was pretty awesome.)

Wikipedia claims chromatic aberration does not occur with contact lenses,
however it always occurs with all lenses to some degree, the more curved the lens is the more noticeable it becomes.


http://www.tlc-systems.com/artzen2-0047.htm
« Last Edit: 02/11/2013 19:02:50 by RD »
 

Offline alancalverd

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Re: Rainbow in my left eye
« Reply #2 on: 02/11/2013 19:05:13 »
IIRC the natural lens has significant chromatic aberration which is "corrected" by the brain. Adding an artificial lens will alter the aberration and it is possible that the brain can't then correct properly for a point source because there is no clue as to what it should look like.   
 

Offline RD

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Re: Rainbow in my left eye
« Reply #3 on: 02/11/2013 20:35:52 »
Diffraction , (rather than refraction) , can also cause "rainbow" auras ...


https://en.wikipedia.org/wiki/Diffraction_grating

But refraction (dispersion) is the more likely candidate for an effect caused by a lens.
« Last Edit: 02/11/2013 20:42:09 by RD »
 

Offline syhprum

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Re: Rainbow in my left eye
« Reply #4 on: 03/11/2013 09:25:25 »
I wonder if some of the colour fringing was due to "Newton's rings" a phenomenon caused by a small gap between the lens and the eyeball which is well known to users of drum type scanners.   
 

Offline Bored chemist

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Re: Rainbow in my left eye
« Reply #5 on: 03/11/2013 09:43:41 »
I'm fairly short sighted (about -9 D in both eyes) and if I look at a small bright object (a light or a reflection from something or whatever) through the edges of my glasses rather than through the middles it is spread out into a spectrum. It's a bit of a distraction, but it does let me distinguish between different sorts of light source (not a very useful skill- but I'm nerdy enough to think it's interesting).
I'm pretty certain the effect is due to chromatic aberration. In effect- the edges of the lens are acting as prisms.
 

Offline Taelia

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Re: Rainbow in my left eye
« Reply #6 on: 03/11/2013 10:01:16 »
Thank you for your replies, I found alan's answer an especially interesting one.
And its indeed what Bored Chemist describes, I also remember being able to distinguish different sorts of light sources.

Anyone knows why it would only happen to one of my eyes?
 

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Re: Rainbow in my left eye
« Reply #6 on: 03/11/2013 10:01:16 »

 

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