Are my polarized prescription sungalsses defective?

[Mehran Ziadloo]

Disclaimer, I just saw the same exact conversation from 2003 and I'm asking pretty much the same question since I didn't get my answer from that one.

I just got my polarized prescription sunglasses and while I was checking them in the store, I didn't see any issues with them. But as soon as I looked at a computer screen with them at home, the problem was very obvious. The best way I can explain it is by showing it to you:

https://ibb.co/rd80TmQ

As you can see in the image above, it's very ugly and the distortion is all over the place. The white background of the image is a laptop's LCD.

I do have the option of going back to the store and demanding a replacement. But before I do that, I was wondering if I should ask for new ones without polarization since such problems are inevitable or they've just screwed up and they can actually deliver uniformly polarized prescription sunglasses? Please in your answer include conditions where such defects might be inevitable (like maybe astigmatism?).

Thanks.
Mehran

[Mehran Ziadloo]

BTW, if you have any idea how this could have happened, I would love to hear your thoughts. Is this problem due to cheap lens or the craftsman who cut them into shape has screwed up?

[Robert]

Mehran Ziadloo <mehran...@gmail.com> wrote in part:

> Disclaimer, I just saw the same exact conversation from
> 2003 and I'm asking pretty much the same question since I
> didn't get my answer from that one.

You checked -- good for you!

> I just got my polarized prescription sunglasses and while
> I was checking them in the store, I didn't see any issues
> with them. But as soon as I looked at a computer screen
> with them at home, the problem was very obvious. The best
> way I can explain it is by showing it to you:
>
> https://ibb.co/rd80TmQ
>
> As you can see in the image above, it's very ugly and the
> distortion is all over the place. The white background of
> the image is a laptop's LCD.

I don't view images. But you should be aware that polarization
runs in different directions, say up-down versus left-right.
Many displays generate polarized light and will "black out"
when viewed through polarized lenses _at_a_particular_angle.
Is the problem the same when you rotate the glasses or the
screen 90deg ?

> I do have the option of going back to the store and demanding
> a replacement. But before I do that, I was wondering if I
> should ask for new ones without polarization since such
> problems are inevitable or they've just screwed up and
> they can actually deliver uniformly polarized prescription
> sunglasses? Please in your answer include conditions where
> such defects might be inevitable (like maybe astigmatism?).
>
> Thanks. Mehran

HTH
-- Robert

[Mehran Ziadloo]

Hi Robert,

Thanks for the reply. I wish that Google Group supported embedded images so you don't have to click on an external link to see the image. But unfortunately, it doesn't. The best I can describe my prescription sunglasses' polarization situation is that it's not uniform. Meaning that it has patterns composed of curves. The shape of the curves gives you a feeling as if they are caused by cutting the lenses. As if when the crafts(wo)man was cutting them into shape, the lenses were heated and caused the distortions. At least that's my personal (uneducated) theory. The curves are kinda pretty but definitely, they are not making my glasses any better.

To answer your question, when I rotate the glasses while looking at some LCD, the amount of light that gets through changes (as it should). I can still see the aforementioned patterns, it's just that they'll be less pronounced (they are most pronounced when I keep them level). But the main issue is the curved patterns.

And BTW, the explained distortion only applies to the polarization, and if I'm looking at some scenery where polarization does not do anything, I won't be seeing these patterns. That's why I missed them when I was checking them in their shop.

Thanks again,
Mehran

[Robert]

Mehran Ziadloo <mehran...@gmail.com> wrote in part:

> Hi Robert,
>
> Thanks for the reply. I wish that Google Group supported
> embedded images so you don't have to click on an external
> link to see the image. But unfortunately, it doesn't. The

Nor should it. I'm reading on USENET which never did.

> best I can describe my prescription sunglasses' polarization
> situation is that it's not uniform. Meaning that it has
> patterns composed of curves. The shape of the curves
> gives you a feeling as if they are caused by cutting the
> lenses. As if when the crafts(wo)man was cutting them into
> shape, the lenses were heated and caused the distortions. At
> least that's my personal (uneducated) theory. The curves
> are kinda pretty but definitely, they are not making my
> glasses any better.

When I look at the (untinted) rear window of my car, I see
an interesting checkerboard pattern which shifts as I rotate
my head. I presume this is deliberate to reduce glare.
The world is a very sophisticated place underneath.

> To answer your question, when I rotate the glasses while
> looking at some LCD, the amount of light that gets through
> changes (as it should). I can still see the aforementioned
> patterns, it's just that they'll be less pronounced (they
> are most pronounced when I keep them level). But the main
> issue is the curved patterns.

They might be accidental from non-uniform heat treatment,
or they might be deliberate to achieve some effect like
circular polarization. The latter should be more uniform,
and you could check by looking at a uniform polarized source
like a white laptop screen.

> And BTW, the explained distortion only applies to the
> polarization, and if I'm looking at some scenery where
> polarization does not do anything, I won't be seeing these
> patterns. That's why I missed them when I was checking them
> in their shop.

Then it might be hard to argue unless you can demonstrate
non-uniformity indicating manufacturing error.

> Thanks again, Mehran
-- Robert

[Mehran Ziadloo]

What I can say for sure is that the patterns I'm complaining about are NOT deliberate. The curves are very random, more like what you get as a result of a natural process.

So, my question still stands. Should I just ask for non-polarized lenses next time or this is just a screw up which can be avoided? I'm asking this because even though I've had prescription sunglasses before but they were never polarized and I don't know if this is a common issue that most people learn to live with or not.

[Mehran Ziadloo]

I just made a new discovery! And it's very interesting. I've put the aforementioned polarized glasses on top of my non-polarized prescription glasses. And similar distortions exist even on my non-polarized lenses. I believe this means that such distortions exist on all my previous lenses even though I could never see them before. I have 4 pairs of glasses, all roughly with the same prescriptions (gathered over the years). Similar (but not identical) distortions can be observed if I put the polarized lenses in top of them and look at a computer LCD.

I'm still not sure if this counts as a defect or not. In fact, after this discovery I'm even less sure.

[Robert]

Mehran Ziadloo <mehran...@gmail.com> wrote in part:

> I just made a new discovery! And it's very interesting. I've
> put the aforementioned polarized glasses on top of my
> non-polarized prescription glasses. And similar distortions
> exist even on my non-polarized lenses. I believe this means
> that such distortions exist on all my previous lenses even
> though I could never see them before. I have 4 pairs of
> glasses, all roughly with the same prescriptions (gathered
> over the years). Similar (but not identical) distortions
> can be observed if I put the polarized lenses in top of
> them and look at a computer LCD.

Distortions are present in all lenses, moreso with cylinder to
correct astigmatism. And very much worse if the lenses have
not been properly fitted (centered) on their eyes. On the
table or a sheet of ruled paper the distortions are obvious.

> I'm still not sure if this counts as a defect or not.
> In fact, after this discovery I'm even less sure.

Something repeatable is not a defect.
It might be a design flaw.

-- Robert

[Judy Brisson]

Computer screens are often polarized and will not be at the same angle as your glasses so you will get those weird effects if using sunglasses to view your computer. The issue is with your monitor, not the glasses. However, you should not be using sunglasses to view your computer anyway. Use clear, non polarized glasses with your computer.

[Mehran Ziadloo]

Thanks, Judy for your input.

I understand that polarized glasses are not made for looking at computer screens and I've done so only to test them. But that does not mean that problem is the screen. I can see the issue even if I look at the sky by them. The patterns are not as pronounced as the computer screen but they are there. I can also see them when I wear the glasses and look in the mirror and see my eyes behind the lenses (when the light goes through the lenses twice). There's no doubt in my mind that this is not how these lenses are supposed to be but at the same time I'm not sure if it's the maker's fault or this due to my prescription. Basically, I don't know if I should ask them to remake new polarized lenses for me or ones without polarization.

Regards,
Mehran

[Bob F]

What did they say when you addressed this problem to the place that sold
you the glasses?

[Mehran Ziadloo]

Hey Bob,

They are happy to replace them for me. It's just that they are saying there's no guarantee that the new ones will be any better. Apparently, the problem is the result of the pressure they apply when they are adding the polarized coating.

[Bob F]

On 8/4/2022 7:41 AM, Mehran Ziadloo wrote:
> Hey Bob,
>
> They are happy to replace them for me. It's just that they are saying there's no guarantee that the new ones will be any better. Apparently, the problem is the result of the pressure they apply when they are adding the polarized coating.

That is informative.