RE: Color Perception: How does coffee affect color perception?
RE: Color Perception: How does coffee affect color perception?
- Subject: RE: Color Perception: How does coffee affect color perception?
- From: Roger Breton <email@hidden>
- Date: Sat, 27 Jul 2013 15:11:06 -0400
Daniel and Bob,
You guys are great!
This may be silly but my first, naïve reaction, is to consider these physiological changes as independent of "color perception"?
To me, "perception" refers to some cognitive processing.
The fact that, Bob, you report seeing with a stronger "blue" intensity after your cataract removal indicate that your brain does receive the new retinal information, but how is your brain "adapting" to the change is my question?
Always curious to know / Roger
-----Original Message-----
From: Bob Frost [mailto:email@hidden]
Sent: Saturday, July 27, 2013 2:40 PM
To: Roger Breton; email@hidden
Subject: Re: Color Perception: How does coffee affect color perception?
Hi Roger,
Loads of stuff on this, from popular to highly complex articles.
I became interested in this when I had a lens with cataract replaced with a clear plastic lens. Back in the hospital waiting room, as my vision slowly returned in the operated eye, I saw that the nurses uniforms were not white/grey stripes, but white/blue stripes! With the eye that had not yet been operated on, the uniforms were still white/grey. After the second eye was done, blues were suddenly much brighter than before. While I had just the one IOL, I played about with yellow filters to see what strength of filter equaled my yellowed lens that had not been replaced. Great fun, and now everything is not only bluer, but sharper as well.
Here are just a few bits from various websites:
"Also as one ages the lens becomes more yellow. People in their 50s will, for example, exhibit clearly lower spectral sensitivities at the short wavelength end of the spectrum than 10 year olds."
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"In addition to its refractive role, the natural lens inside your eye is also responsible for filtering high-energy blue light commonly found within the sun's rays and some artificial light. As part of the aging process, your natural lens gradually turns yellow and it is thought that this change in color may help to protect the aging retina by filtering more of the these harmful wavelengths."
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"Age-Related Eye Change #3
The lens of the eye gradually yellows with age.
Impact: The yellowing of the eye lens affects color perception. For example, the yellowing lens tends to absorb and scatter blue light, making it difficult to see differences in shades of blue, green, and violet. Colors may seem duller, and contrasts between colors will be less noticeable. This may cause confusion when picking out clothes or performing other tasks that require color perception. It also may become difficult to tell where an object ends and its background begins, making it difficult to see curbs or steps, for example.
Compensation: A few specific adjustments to lighting and color choices should help alleviate the effects of minor lens yellowing. Try this:
•Choose halogen or fluorescent bulbs specifically designed to improve color rendering. Bulbs with a color-rendering index (CRI) above 80 may best help older eyes with color definition.
•Use warm contrasting colors, such as yellow, orange, and red, in your home to improve your ability to tell where things are and make it easier to perform daily activities.
•Put colored tape on the edge of steps to help make them easier to navigate."
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"Lens
•Becomes more yellow with age: Cataracts The graph on the right shows the optical density (-log transmittance) of the lens as a function of wavelength. The curves show the change in density with age. More short wavelength light is blocked at increases ages." - graph attached.
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"Also with age, there is a fall in light transmission by the lens, associated with increased light scatter, increased spectral absorption, particularly at the blue end of the spectrum, and increased lens fluorescence. A major factor responsible for the increased yellowing of the lens is the accumulation of a novel fluorogen, glutathione-3-hydroxy kynurenine glycoside, which makes a major contribution to the increasing fluorescence of the lens nucleus which occurs with age. Since this compound may also cross-link with the lens crystallins, it may contribute to the formation of high-molecular-weight aggregates and the increases in light scattering which occur with age."
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"Lerman & Borkman (1976) described two age-related fluorescent compounds which develop in the lens nucleus. The first showed activation at 340–360 nm with emission at 420–440 nm and could be responsible for lens yellowing. It increased with lens age following the same pattern as the increase in insoluble fractions of lens proteins with age (Clark et al. 1969, Jedziniak et al. 1975). The second, which appeared to be a secondary product of the former being detectable only after the first decade of life, absorbed light at 415–435 nm with emission at 500–520 nm. It remained at a relatively low level until the fourth or fifth decade. A significant increase in the concentration of this fluorogen was seen in advanced, brown colored nuclear cataracts. Lerman & Borkman also noted a progressive decline in transmission of visible light in the aging lens which could be correlated with the increasing concentration of these pigments in the lens nucleus."
Bob Frost.
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From: "Roger Breton" <email@hidden>
Sent: Saturday, July 27, 2013 5:05 PM
To: <email@hidden>
Subject: RE: Color Perception: How does coffee affect color perception?
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