Friday, May 10, 2024

Creation Moment 5/11/2024 - How did the eye figure that out?

Thank you for making me so wonderfully complex!
Your workmanship is marvelous—how well I know it.
Psalm 139:14


"The eye has a problem: different wavelengths focus differently. 
Blue light, with a shorter wavelength, is more sensitive to longitudinal and transverse chromatic aberration than red

Q: With one lens, and one retina, how does the eye achieve good focus across all wavelengths? 
Q: How does it avoid contrast reversal when scanning across a scene? 
Scientists have thought that the blue-sensitive cones used macular pigment to selectively absorb short wavelengths to offset the effects of aberration. 
But now, writing in Nature, four optical experts from Spain and
Massachusetts have calculated and measured the optical quality of real
eyes, and found that blue light is not as blurred as previously thought.

For one thing, the blue-sensitive cones in the retina have a narrower bandwidth that limits the blurring, and the red and green sensitive cones have bandwidth that overlaps somewhat. 

The scientists did experiments with human subjects and also took into account monochromatic aberration across the full spectrum of visible light and the spatial density of the different cones across the retina. They found that, although there were trade-offs and
compromises, all the cones, working together, achieve the optimum response with minimum aberration:

"It has been widely assumed that chromatic defocus from the eye’s optics degrades the retinal image of short-wavelength light. But this assumption has not previously been tested in a manner that takes into account all of the eye’s optical aberrations, measured at multiple wavelengths. We have shown that there is actually little variability in the eye’s image quality, as quantified by MTF [modulation transfer function, a measure of image contrast quality], across the visible spectrum. Wave aberrations cause the visual system to sacrifice resolution at a single wavelength but allow it to gain approximate constancy in spatial sensitivity across the spectrum. This constancy might provide an even more effective solution to the problems of chromatic blur than could be attained by attenuation and sparse sampling of short-wavelength light in an eye with perfect optics."

Their paper is entitled, “Imperfect optics may be the eye’s defense against chromatic blur.” They also suspect that macular pigment, not therefore needed to improve optical quality, may instead be present to help protect the eye from high-wavelength damage.

This is just one example of the kind of detail in engineering the body
performs so effortlessly, that we take for granted. 
--In evolutionary terms, every little improvement would be caused by accident, and would have to benefit survival so much that all without the accident die. 
Clearly, intelligent design is the superior explanation. 
--Here we see the interesting design approach that, given the physical constraints of the laws of electromagnetic radiation, designing an apparent “imperfection” can actually lead to greater overall performance! 
Q: How did the eye figure that out?" 
CEH