Excellent and understandable article by Nathan Lents. It is closely related to the recent article by Erkki Vesa Rope Kojonen and another article that Lents was recently published.
This continues, in a way, some of the first conversations I had with Nathan:
Nathan Lents excellent explanations of the tapetum lucidum and “backward retinas” brings to mind an article I read from some Young Earth Creationist ID’er source years ago. (Sorry I can’t recall enough details to post a citation or link.)
The argument claimed that because land animals need to protect their eyes from UV light damage, the reverse design of the eye was actually advantageous and yet another point in favor of Intelligent Design. Yes, somehow all of those “front structures” shield UV light rays from reaching the “back structures” which would otherwise be damaged by such exposure.
Another problem with that explanation: fish have the same backwards retinas.
Indeed. I think the article I recalled assumed that fish eyes don’t have to deal with much UV light damage because they are underwater—but, obviously, that is just plain wrong. In fact, when I had koi and goldfish ponds long ago, I added “sunscreen pond dye” to the water at the height of summer to reduce UV penetration. Otherwise some koi varieties can get seriously elevated cancer rates, and due to their high value it is a good investment to simply buy the dye. (It also gives the water a beautiful tropical ocean shade of blue-green.)
Wrong, perhaps, for fish that live very near the surface. But I would suppose that a few dozen meters of water would get rid of the problem, not to mention all the abyssal species with the same backwards retinas.
Indeed, but it was evident that the authors of the aforementioned YEC article weren’t thinking all that deeply.
(In terms of the science, they were in way over their heads. Backwards retinas or not, that’s the way I see it.)
Not getting this. If fish did all get a lot of UV exposure, wouldn’t that help the creationists’ case?
Yet another problem with that explanation: one octopus spends a lot of time on land.
Relevant fun fact: Hammerhead sharks can get sunburnt.
I nominate you to advise them on this point.
Go ahead … Don’t be koi. 
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