Evolution: more magic retinal design (Evolution)

by David Turell , Thursday, March 03, 2022, 14:46 (786 days ago) @ David Turell

Mitochondria focus light:

https://www.sciencealert.com/mitochondria-in-the-mammalian-eye-act-as-microlenses-to-he...

"Now, a study has added a surprising new lens to this process. In cone receptors, mitochondria – which you might know as the powerhouse of the cell – appear to be acting like little 'microlenses' to help deliver photons to the nerve cells.

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"This seemed particularly weird to the researchers, as mitochondria are positioned in the light-sensitive outer segment of the cones in our retina. This means that light can hit the mitochondria directly, which could potentially cause photons to scatter off in weird directions, or even be absorbed, stopping light from reaching nerve cells altogether.

"'These complex, lipid-rich organelles are also poised to affect light passage into the outer segment," write the researchers, led by National Eye Institute scientist John Ball.

"'Here, we show, via live imaging and simulations, that despite this risk of light scattering or absorption, these tightly packed mitochondria 'focus' light for entry into the outer segment and that mitochondrial remodeling affects such light concentration."

"'The lens-like function of mitochondria also may explain the phenomenon known as the Stiles-Crawford effect," said Ball.

"The Stiles-Crawford effect is a property of cone receptors where light that enters the center of the pupil produces more of a response in our cone cells than light entering closer to the edge.

"The team found experimentally and using computer models that mitochondrial interaction with light matched the Stiles-Crawford effect, meaning the mitochondria could be the cause.

"'This 'microlens'-like feature of cone mitochondria delivers light with an angular dependence akin to the Stiles-Crawford effect, providing a simple explanation for this essential visual phenomenon that improves resolution," the team wrote."

Comment: more wonders of the 'wrongly designed' retina atheists love to discuss.