What is the point of "Shutter" style sunglasses?

General Questions
#1

While at places where sunglasses are sold, I have been seeing these odd sunglasses for sale. They look like this
http://www.amazon.com/STRONGER-SHUTTER-SHADES-CELEBRITY-SUNGLASSES/dp/B001GDN4JE/ref=sr_1_1?ie=UTF8&s=apparel&qid=1260226917&sr=1-1

What is the point of this product? I tried a pair on, and not only did they limit my vision exactly as one would imagine they would, they seemed to be completely ineffective as sunglasses, as in the sun got in my eyes exactly as if I wasn’t wearing any type of sunglasses. Again, what is the purpose of this product? I see them available for sale everywhere, but I’ve never seen anyone wear them. The only thing I can find out about them is that they are somehow related to well known jackass Kanye West.

#2

They look cool, at least to the douchebags and hipsters who wear them. As far as the usual purposes of sunglasses go, they make it harder for people to see exactly where you’re looking. As you found out, they don’t block the sun.

#3

I don’t think most fashion accessories have a point. The products you point out is something I’d classify closer to fashion accessory than sunglasses (which actually have a functional purpose).

#4

Oddly, they do work to block the sun - even with this coarse a mesh - the total amount of light entering your eyes is reduced by the bars that obscure some of it. Similar to this:
http://www.wilderness-survival.net/cold-6.php

Another possibly related phenomenon - in very bright sunlight, it can be painful to open both eyes, but comfortable enough to open one or the other.

#5

I remember seeing something like that in “Sergeant Preston of the Yukon” in the early 60’s, and maybe even had some that you cut out from the back of a cereal box. I always thought the point was to cut the glare without being blocked by blowing snow.

#6

That’s right, but it’s also because in a survival situation, suitable materials to make proper sunglass lenses (i.e. dark, but clear) are likely to be difficult to source.

As a thought experiment, imagine sunglasses made of a gid as fine as a diffraction grating or polarising filter… then double the breadth of the obscure and transparent strips - keep doing that… Is there a point where it becomes completely ineffective in reducing glare?

(I’m going to say “yes, when the bands are bigger than your eyes”)

#7

No doubt inspired by Eskimo sunglasses.