Polarized sunglasses 3.50

The 60 minutes episode about Luxottica:

anatman wrote: ↑ Also, it's useful to keep in mind that sunglasses have a limited effective life, because the UV absorbing agents don't have an unlimited capacity to absorb UV light. Those bonds being pumped to reactive excited states will decay in off reactions over time. A person buying a $5 pair every summer will have much much better protection than someone that spent $2,000 on their glasses and uses them for several years--also why it's a good idea never to buy sunglasses that have been sitting in the sun (e.g. from beach vendors).
quantum mechanics demonstration of Bell's Theorem.

Is this true and fact checked? When I search online is only sunglass sellers that say this. The lens block UV,not absorb.

CNN https://www.cnn.com/2017/05/30/health/s ... index.html and McGill state otherwise https://www.mcgill.ca/oss/article/techn ... eally-need

Just an FYI, if you're concerned about the glasses really being polarised, put a pair on and take a second of the same kind and position the lenses at 90 degrees to the ones you're trying on. One on your face and the other with one of the lenses in front of your eye, but pointing down. Like a sideways T, -l You should not be able to see anything. If you can see through, one one the glasses are not polarised.
No bargain is worth your eyesight.

OT a bit but this episode of marketplace on eyewear was eye opening:

https://www.cbc.ca/marketplace/m_episod ... des/framed

Now, assuming this. I would imagine it's probably also true of the sunglasses market. When the CEO of a big glasses company outright says it has little to do with the actual cost of the glasses but it's a fashion statement, you really have to wonder...

So are these overstock, or is the 'rama price sticker part of the packaging?

Bobberts wrote: ↑ Is this true and fact checked? When I search online is only sunglass sellers that say this. The lens block UV,not absorb.

CNN https://www.cnn.com/2017/05/30/health/s ... index.html and McGill state otherwise https://www.mcgill.ca/oss/article/techn ... eally-need

Umm... CNN and the blog post aren't saying what you think they are (they aren't using "block" in a scientifically rigorous way). Light can scatter (i.e. "blocking") or be absorbed. You don't want to use scattering agents (e.g. titanium dioxide nanoparticles) in sunglasses because it would make them blurry (opaque, or even into a mirror). So yeah, unless you've come up with a material science breakthrough, sunglasses use UV absorbing agents.

sam123 wrote: ↑Just an FYI, if you're concerned about the glasses really being polarised, put a pair on and take a second of the same kind and position the lenses at 90 degrees to the ones you're trying on. One on your face and the other with one of the lenses in front of your eye, but pointing down. Like a sideways T, -l You should not be able to see anything. If you can see through, one one the glasses are not polarised.
No bargain is worth your eyesight.

I checked against a white screen on my cell phone screen prior to purchasing and they are polarized.

Ottomaddox wrote: ↑ So are these overstock, or is the 'rama price sticker part of the packaging?

The sticker is printed as part of the packaging.

DragOnT wrote: ↑ Finally some one understands better.

Luxottica and safilo Control almost the entire market. If someone new pops up they buy them out to regain their monopoly.

anatman wrote: ↑ Umm... CNN and the blog post aren't saying what you think they are (they aren't using "block" in a scientifically rigorous way). Light can scatter (i.e. "blocking") or be absorbed. You don't want to use scattering agents (e.g. titanium dioxide nanoparticles) in sunglasses because it would make them blurry (opaque, or even into a mirror). So yeah, unless you've come up with a material science breakthrough, sunglasses use UV absorbing agents.

Was typing on the phone an looks like I'm incoherent when on the phone.

My comment was directed to this statement. 'it's useful to keep in mind that sunglasses have a limited effective life, because the UV absorbing agents don't have an unlimited capacity to absorb UV light. Those bonds being pumped to reactive excited states will decay in off reactions over time.'

The links state the protection is for life, and the protection does not diminish over time.

The UV absorbing vs blocking was only my understanding or misunderstanding and is not related.

I'm worried that the dollar store stuff don't meet manufacturer's QA/QC checks. If you're luck it's something cosmetic. If you're not the it could be something functional such as no UV coating. I can't see any company trying to maximize EPS throwing out "bad" product when there's a whole market waiting to buy them for distribution through authorized reseller channels. I don't think this is tinfoil hat thinking just thinking like a capitalist.

Bobberts wrote: ↑The links state the protection is for life, and the protection does not diminish over time.

The UV absorbing vs blocking was only my understanding or misunderstanding and is not related.

Does your sunscreen come in an opaque container and does it expire? Does every plastic thing made for the outdoors (from garden hoses, to sheds, etc) eventually discolor, warp, and crack from exposure to sun, despite being impregnated with immense amounts of UV absorbing agents ("UV stabilizers")? It's an incredibly ubiquitous problem, and the degradation pathways of common UV absorption compounds are well known.

In terms of sunglasses here are some papers to start:

APA Chou, B. Ralph*; Dain, Stephen J.†; Cheng, Brian B.‡ Effect of Ultraviolet Exposure on Impact Resistance of Ophthalmic Lenses, Optometry and Vision Science: December 2015 - Volume 92 - Issue 12 - p 1154-1160

Masili, M., Ventura, L. Equivalence between solar irradiance and solar simulators in aging tests of sunglasses. BioMed Eng OnLine 15, 86 (2016). https://doi.org/10.1186/s12938-016-0209-7
doi: 10.1097/OPX.0000000000000730

vistaliving wrote: ↑ Aren't most sunglasses, cheap, designer, branded come from the same manufacturer.

That's the same for every product. It's all about brand name. You pay for the name. Why do you think LV, Prada, Gucci, Cartier have followers.......