Polarized 1.67 Progressive PAL Failure?

**icare** · 12-15-2010, 11:01 AM

I just got a new Supercede WS12 in Polarized 1.67 Grey with a back-side A/R. The first time I drove with them I immediately noticed significant luster (binocular interference). OK, time to adapt, right? Well, on closer inspection I discovered that the amount of polarization effect varies in different sections of the lens. I've never seen this in single vision jobs. I wonder if this a possible complication of all polarized progressives, or maybe just 1.67, or maybe just Freeforms, or even maybe just aspherics. The Supercede is a double aspheric design.

OD +0.25 sphere
OS Plano
+2.00 Add
PD 33/33.5

Came through with a 4.00 base and mounted in a 53/18 traditional full rim frame with a normal B dimension (not a sun frame or super wrap or oddball frame). Average lens thickness is 2.0 - 2.2mm.

The problem is best observed by waving the lenses horizontally (without torsion) in hand motion while observing a distant reflective surface through the lens. There is simply more polarization centrally than peripherally and it is observable in the top distance carrier portions as well as in the lower progressive zones, equally in both lenses. I removed the lenses from the frame to insure that they were not mounted too tightly and the observation was identical. The irregularity of the polarization was not similar to the mounting point distortion you'd expect to see in a lens that was simply mounted too tightly, either. I actually finished the job myself to be sure that the mounting was correct to eliminate such distortions.

Has anyone else experienced similar polarization irregularities in PALs? It renders the polarization virtually useless and I'm not sure yet how I'll proceed with the redo. I'm just glad it's me and not a patient! :)

**WFruit** · 12-15-2010, 11:15 AM

They are defective lenses. It has nothing to do with them being PAL's, Free Form or otherwise. Seiko just has a bad batch of the 1.67 polarized blanks (which is why a number of their base curves are on back order for the 1.67 Polarized).

**icare** · 12-15-2010, 11:46 AM

Wow! Awesome and prompt reply.

Thanks for the industry update - looks like I'm going to stay in Seikotown and opt for a proper redo.

Enjoy the season!

**Just Optician** · 12-17-2010, 12:30 PM

Just curious. Why 1.67 for your prescriptions? It didn't cause the problem but it certainly doesn't help.

**icare** · 12-17-2010, 12:38 PM

I wanted to experience the material myself for once. I take it that you're not a fan of 1.67? Any insight you'd like to provide is welcome.

**DragonLensmanWV** · 12-17-2010, 01:06 PM

At that kind of power, you won't experience any of the poor optical properties that 1.67 has. But if you're a -8.00 or above, you would see the effect that a poor ABBE has when you look off center.

**icare** · 12-17-2010, 01:11 PM

So the advantages of 1.67 for the general masses are.... ? ? ?

Some pros and not just cons?

**WFruit** · 12-17-2010, 01:32 PM

Thinner, lighter lenses. MR-10 1.67 is also excellent for drill mount frames.

I'm only about a -7.00, but I don't see the abbe issues in either 1.67 or 1.74. Or at least they don't bother me. (Currently I'm wearing a Seiko 1.74, but I also have a Seiko Super MV 1.67 pair.)

This is an ok reference for material properties. http://en.wikipedia.org/wiki/Corrective_lens The chart most of the way down the page is nice. Of special notice is the light reflectance column. Really nice to show why people need A/R on the higher index materials.

**AngeHamm** · 12-17-2010, 01:44 PM

Originally Posted by WFruit

Thinner, lighter lenses. MR-10 1.67 is also excellent for drill mount frames.

I'm only about a -7.00, but I don't see the abbe issues in either 1.67 or 1.74. Or at least they don't bother me. (Currently I'm wearing a Seiko 1.74, but I also have a Seiko Super MV 1.67 pair.)

Ditto. I'm a -9.25 total power and I see none of the problems commonly ascribed to these materials.

**DragonLensmanWV** · 12-17-2010, 02:03 PM

Drove me nuts at -15.00, until the 1.70 came out. Try this:
Take the lampshade off a lamp and darken the room, other than the one light bulb. Look directly at the bulb in the center of the lens, no problem. Then move your gaze out towards the periphery of the lens by turning your head and watch your one light bulb magically turn into three - one red, one white and one blue.
You whippersnappers with your tiny Rx might not notice this effect.:bbg:

**myoman** · 12-17-2010, 03:19 PM

I'm wearing 1.67 and do not experience those "effects". Total power on my rx is about -4.00. I have progressive lenses in 2 pair of glasses I switch back and forth with depending on my mood. 1 pair is Zeiss individual and the other is a Shamir AutographII. Perhaps it is the optical designs as both pair are compensated rxs and are very clean edge to edge. I tried wearing Seiko progressives on 2 occasions without success.

**gunner05** · 12-18-2010, 09:56 AM

See, I'm a -1.50 with buck and a half worth of cyl. I can see the abberation in both poly and 1.67. Of course, I know what I'm looking for so that has a lot to do with it.

**WFruit** · 12-18-2010, 10:06 AM

It REALLY bothers me in Poly, but not in 1.67 or 1.74 (both have the same abbe). I know it's there and what it looks like, I just don't notice it.

And this is why there are different lens materials and designs. Not everything works for everyone.

**xiaowei** · 12-18-2010, 03:17 PM

Originally Posted by WFruit

It REALLY bothers me in Poly, but not in 1.67 or 1.74 (both have the same abbe). I know it's there and what it looks like, I just don't notice it.

And this is why there are different lens materials and designs. Not everything works for everyone.

Hmm, just another case of bad Poly reputation!? Given the fact, that Poly Abbe is just 10% less than 1.67 resp. 1.74 Abbe , there should be (almost) no noticeable difference when going to Poly. Why is it always considered sooo bad?

I´m pretty sensitive to lens color fringing and can detect it also in high Abbe lenses, however one get´s used to it...

Interestingly, I found that depending on design, there is also varying "on axis" fringing in PAL lenses from different manufacturers, because apparently due to thinning (and other "residual" design given) prism, the "center" of the distance area (with minimum surface astigmatism) is not also the ("local") optical center of the lens (with would cause no light refraction at all). I noticed a big change once when going from a simpler PAL design to one by a famous German manufacturer, actually to the worse:(

.

**WFruit** · 12-20-2010, 10:00 AM

Originally Posted by xiaowei

Hmm, just another case of bad Poly reputation!? Given the fact, that Poly Abbe is just 10% less than 1.67 resp. 1.74 Abbe , there should be (almost) no noticeable difference when going to Poly. Why is it always considered sooo bad?

For the same reason that 1 degree difference in axis can make a difference in how well a patient sees. At some point even the smallest difference makes a difference.

For me, it's not a matter of "bad poly reputation." It's a matter of the fact that I've worn Poly and don't like it.

**AngeHamm** · 12-20-2010, 12:01 PM

Originally Posted by WFruit

For the same reason that 1 degree difference in axis can make a difference in how well a patient sees. At some point even the smallest difference makes a difference.

For me, it's not a matter of "bad poly reputation." It's a matter of the fact that I've worn Poly and don't like it.

Now there I completely agree. If my axis or PD are off, even well within "tolerance," I know it and have problems. And poly gives me terrible eyestrain and headaches; I won't touch it.

My pickiness is very good for my patients, however. My own exacting standards are passed on to my lab work on their lenses as well.