What does "Pl" mean?

#15 12-22-2006, 12:15 AM

In article <AMigh.13494$wc5.1237[at]newssvr25.news.prodigy.net> ,
William Stacy <wstacy[at]obase.net> wrote:
- quote -

> David Combs wrote:
> > So, for someone who likes executives (can switch eye-direction
> > from all the way left to all the way right, while keeping
> > the nose *still*, no-rotation-required) -- in your estimation,
> > are "flat-tops" (even) better?
> > > Not better in theory. In practice, a 35 mm wide seg flat top works fine
> for most, but you can't beat the exec or single vision for what you're
> describing.
> > > (I was told by one seemingly-knowledgeable person that
> > they were *much* better, newer design, less distortion,
> > etc.)
> > > Was he right? wrong?
> > > wrong on all 3 counts. execs are a more recent design than flat tops,
> have less prism, less jump, and are a better design for many people.
> > > He also told me that executives were made only in the U.S. --
> > never got popular in Europe.
> > > > may be true, as it for many years was a proprietory lens owned by
> American Optical Corp.
> > (of course(?) they like progressives there, but I can't
> > stand the idea of having to always twist my head to
> > look left and right.
> > > > Then get an exec or a ft-35. You can get a ft 45, but there's so much
> jump and prism in the seg that I hate them.

Thanks so much!

David

#14 12-14-2006, 07:48 PM

David Combs wrote:

- quote -

> So, for someone who likes executives (can switch eye-direction
> from all the way left to all the way right, while keeping
> the nose *still*, no-rotation-required) -- in your estimation,
> are "flat-tops" (even) better?
Not better in theory. In practice, a 35 mm wide seg flat top works fine

for most, but you can't beat the exec or single vision for what you're
describing.

- quote -

> (I was told by one seemingly-knowledgeable person that
> they were *much* better, newer design, less distortion,
> etc.)
> Was he right? wrong?

wrong on all 3 counts. execs are a more recent design than flat tops,
have less prism, less jump, and are a better design for many people.

- quote -

> He also told me that executives were made only in the U.S. --
> never got popular in Europe.
may be true, as it for many years was a proprietory lens owned by

American Optical Corp.

- quote -

> (of course(?) they like progressives there, but I can't
> stand the idea of having to always twist my head to
> look left and right.
Then get an exec or a ft-35. You can get a ft 45, but there's so much

jump and prism in the seg that I hate them.

#13 12-14-2006, 01:00 PM

In article <gRDeh.6137$hI.997[at]newssvr11.news.prodigy.net> ,
William Stacy, O.D. <wstacy[at]obase.net> wrote:
- quote -

> oh and as to the differences between flat top and exec? The exec has
> "no jump" or double vision (when they are made correctly) at the seg
> line. Flat tops all have prismatic jump at the seg line. The
> difference between glass and plastic D segs is that the glass uses two
> different indices of refraction glass, fused together so there is no
> palpable "ledge" at the seg line as there is on all plastic D segs.
> of course all execs have a ledge, but no jumping allowed...
> w.stacy, o.d.

Thanks for the info!

So, for someone who likes executives (can switch eye-direction
from all the way left to all the way right, while keeping
the nose *still*, no-rotation-required) -- in your estimation,
are "flat-tops" (even) better?

(I was told by one seemingly-knowledgeable person that
they were *much* better, newer design, less distortion,
etc.)

Was he right? wrong?

He also told me that executives were made only in the U.S. --
never got popular in Europe.

(of course(?) they like progressives there, but I can't
stand the idea of having to always twist my head to
look left and right.

THANKS!

David

#12 12-09-2006, 06:09 PM

oh and as to the differences between flat top and exec? The exec has
"no jump" or double vision (when they are made correctly) at the seg
line. Flat tops all have prismatic jump at the seg line. The
difference between glass and plastic D segs is that the glass uses two
different indices of refraction glass, fused together so there is no
palpable "ledge" at the seg line as there is on all plastic D segs.

of course all execs have a ledge, but no jumping allowed...

w.stacy, o.d.

#11 12-09-2006, 06:05 PM

It is a D shaped (with the curved side downward) that is commonly used,
available in 22, 28, 35, 45 mm widths, although I don't think 45 is
avail in glass. The trifocal version is like the D but with two
straight lines, parallel to each other in the D instead of one, in
various separations (between the two lines, where the power is about
half the add of the lower part) from 7 mm to 14 mm. Again, less
availability in glass than plastic (I've only seen 7x28 and 8x35 in
glass. My favorite is the E-D trifocal, which has an exec upper line
and a D style "bifocal" seg set 8 mm down from that line. They used to
have an F-D with a 12 mm separation. A great lens, but my own usage of
it in my practice was not enough to keep Sola making it. Alas.

w.stacy, o.d.

David Combs wrote:
- quote -

> Subject: What's a "flat-top" lens-shape/geometry? (Was: Glass Executive Bifocal)
> I was told (just yesterday) by a glasses-manufacturer I was
> briefly talked to that I should look into "flat tops" (no,
> not navy ships!).
> For bifocals and trifocals, how do these flat-tops differ?
> Pros, Cons?
> (he said they came in glass too)
> Thanks,
> David

#10 12-09-2006, 01:46 AM

Subject: What's a "flat-top" lens-shape/geometry? (Was: Glass Executive Bifocal)

I was told (just yesterday) by a glasses-manufacturer I was
briefly talked to that I should look into "flat tops" (no,
not navy ships!).

For bifocals and trifocals, how do these flat-tops differ?

Pros, Cons?

(he said they came in glass too)

Thanks,

David

#9 12-05-2006, 02:55 AM

Not enough demand. Probably because they aren't teaching ophthalmic
optics like they used to. New people think the lines are "ugly".
They are programmed to "sell" progressives, and that if a lens is more
expensive, it "must" be better.

David Combs wrote:
- quote -

> In article <dkrml2l4d05r8egu0m1qm6nucjhm3operu[at]4ax.com> ,
> Robert Martellaro <robopt[at]nospam.com> wrote:
> > On 15 Nov 2006 11:16:11 -0800, "Norayn" <OliviaNor[at]gmail.com> wrote:
> > > > > I am looking for a source that can provide Glass Lenses in an Executive
> > > Bifocal.
> > > > > Is anyone still making this lens??
> > > Unbelievable!
> First it was executive trifocals they stopped making (glass).
> And now BI-focals?
> Any idea WHY?

#8 12-04-2006, 04:02 PM

In article <dkrml2l4d05r8egu0m1qm6nucjhm3operu[at]4ax.com> ,
Robert Martellaro <robopt[at]nospam.com> wrote:
- quote -

> On 15 Nov 2006 11:16:11 -0800, "Norayn" <OliviaNor[at]gmail.com> wrote:
> > > I am looking for a source that can provide Glass Lenses in an Executive
> > Bifocal.
> > > Is anyone still making this lens??
> Unbelievable!

First it was executive trifocals they stopped making (glass).

And now BI-focals?

Any idea WHY?

And, don't Americans care (any more) about decent-VISION
through their eyeglasses?

Or is it simply greedy CEOs wanting every possible extra
penny in EPS, since (often?) many tens-of-millions of dollars
payout is boosted by that?

- quote -

> > Thank you, Stacye M.
> Stacye,
> Not in the United States.

QUESTION:
Where then can you get them from?

It is available in plastic, and you can still get
- quote -

> ST35's in crown glass.

QUESTION:
And what are *they*?

Thanks,

David

#7 11-15-2006, 09:43 PM

Robert Martellaro wrote:

- quote -

> Not in the United States. It is available in plastic, and you can still get
> ST35's in crown glass.
The passing of an era. The exec glass was a very good lens, an optically

perfect version of the original bifocal invented by Ben Franklin.
American Optical made the best quality Exec (aka e-line, no jump,
Franklin) in glass and the plastic versions never seemed to me to have
the quality as the original. As the years go by, the line gets more
smeared and there is more and more prism at the line (not predictable in
amount). I don't know what the difference in manufacturing technique is
(I never could figure out exactly how they ground those front surfaces),
but I'd bet they are using old glass molds to form the plastic versions,
and they are deteriorating.

We used to make good frames, too...

w.stacy, o.d.

#6 11-15-2006, 07:55 PM

On 15 Nov 2006 11:16:11 -0800, "Norayn" <OliviaNor[at]gmail.com> wrote:

- quote -

> I am looking for a source that can provide Glass Lenses in an Executive
> Bifocal.
> Is anyone still making this lens??
> Thank you, Stacye M.

Stacye,

Not in the United States. It is available in plastic, and you can still get
ST35's in crown glass.

Regards,
Robert Martellaro
~~~~~~~~~~~~~~~~~~
Optician/Owner
Roberts Optical
Wauwatosa Wi.
~~~~~~~~~~~~~~~~~~
"An expert is a person who has made all the mistakes that can be made in a very narrow field."
- Niels Bohr

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