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Polycarbonate vs. regular/plastic lenses

 
 
Charles
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      08-02-2005, 12:25 AM
I posted previously about the difficulty I'm having adapting to my new
lenses. It also occured to me that I was never really all that happy with my
last pair either, even though I wore them for two years. Thing is, that last
pair is when I first switched to polycarbonate. At the time I thought poly
was simply better in all respects, but after reading a little, it seems that
poly is possibly more prone to distortion and such? Is it possible that poly
is not the best choice for people who are more sensitive to distortion? With
this new prescription I've noticed a slight but noticeable variation in
clarity as I look through different parts of the lens, I'm not sure how
normal this is, but I also wonder if there might also be an underlying
distortion that is making me feel so disoriented.

So what's the latest thinking on poly vs. plastic?

If it's relevant, my prescription is like 0.25 power and 1.25 cylinder in
both eyes. TIA
 
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William Stacy
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      08-02-2005, 12:53 AM
Charles wrote:

> Is it possible that poly
>is not the best choice for people who are more sensitive to distortion?
>
>

That's possibly the biggest understatement of the century.

>If it's relevant, my prescription is like 0.25 power and 1.25 cylinder in
>both eyes. TIA
>
>

It is, and makes me wonder what in the world were they thinking, unless
you need special impact resistance afforded by polycarb, or unless you
wanted a drill mount rimless frame.

If either of those conditions do exist, then I'd say try Trivex
material, which is even tougher than poly and the optics are way
better. If neither exist, then go back to good old CR-39 plastic, the
best optically. And while you're at it, ask them why they recommended
them, with your Rx.

w.stacy, o.d.
 
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Charles
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      08-02-2005, 01:11 AM
Thanks for the reply. So I take it poly is known to cause distortion
problems. The reason I originally went to poly (besides that it was sold to
me as being great) was that my last set of frames was the drill-through type.
I stayed with it because I still thought it was good stuff, and also because
they suggested staying the course ("stay with what works") - even though it
may not have really been working all that well previously either.

What do you think a fair policy is regarding a change from poly to CR-39 as
far as paying for it? Should I have to pay the whole bill for the new lenses?
I doubt they'll be willing to pay the entire bill themselves since they
didn't do anything wrong exactly. I also doubt that they'll even agree that
the poly could be the problem. I suspect I'll get a few eye rolls before it's
done ("oh, you read about it on the internet. I see..."). Until I read this
NG I had no idea there were so many options for material. I thought it was
glass, which nobody used anymore, plastic or poly. And the place I dealt with
never really mentioned that any of them were better optically...

On 8/1/2005 7:53:02 PM, William Stacy wrote:
>Charles wrote:
>
>> Is it possible that poly
>>is not the best choice for people who are more sensitive to distortion?
>>
>>

>That's possibly the biggest understatement of the century.
>
>>If it's relevant, my prescription is like 0.25 power and 1.25 cylinder in
>>both eyes. TIA
>>
>>

>It is, and makes me wonder what in the world were they thinking, unless
>you need special impact resistance afforded by polycarb, or unless you
>wanted a drill mount rimless frame.
>
>If either of those conditions do exist, then I'd say try Trivex
>material, which is even tougher than poly and the optics are way
>better. If neither exist, then go back to good old CR-39 plastic, the
>best optically. And while you're at it, ask them why they recommended
>them, with your Rx.
>
>w.stacy, o.d.
>


 
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William Stacy
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      08-02-2005, 04:32 AM
The redo is complicated by the fact that they are drilled rimless. If
you stick with that frame, I'd ask for an upgrade to Trivex. They might
let you off with the difference in price between the 2 materials. If
not, then at least ask for a discounted redo. You can't really redo them
in standard plastic unless you change to a grooved or standard mounting.

If you are willing to change frames, you might get by with just the cost
of the frame. Get creative and don't be bashful. Remind them that they
didn't warn you that the ABBE value (amount of chromatic aberration) of
polycarb is worse than just about any other lens material in the world.
If they don't offer (or can't get) Trivex, why not???

w.stacy, o.d.

Charles wrote:

> What do you think a fair policy is regarding a change from poly to CR-39 as
> far as paying for it? Should I have to pay the whole bill for the new lenses?
> I doubt they'll be willing to pay the entire bill themselves since they
> didn't do anything wrong exactly. I also doubt that they'll even agree that
> the poly could be the problem. I suspect I'll get a few eye rolls before it's
> done ("oh, you read about it on the internet. I see..."). Until I read this
> NG I had no idea there were so many options for material. I thought it was
> glass, which nobody used anymore, plastic or poly. And the place I dealt with
> never really mentioned that any of them were better optically...

 
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William Stacy
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      08-02-2005, 04:39 AM
oh, and also remind them that standard CR39 costs less than poly, so
maybe they should refund you the difference after the remake...

w.stacy, o.d.
 
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Dr. Leukoma
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      08-02-2005, 12:30 PM
Since you had worn polycarbonate in the past, why indeed are you now
having problems? Perhaps there was a significant prescription change,
or change in the base curve of the lenses?


DrG

 
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Charles
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      08-02-2005, 12:47 PM
No, my situation is that I had drill-thru frames last time, but I'm switching
to normal frames this go around. I never really liked the rimless frames,
even though they looked good, because the center part was in my field of view
so much. Right now, the lenses that are bothering me are poly in the regular
frame. The question is whether they will consider switching to plastic worth
the cost of trying, or if they will insist that something else is causing the
problem - most likely me. I'll give it a shot and see. There's no reason not
to stick with Crizal along with the plastic, right?

On 8/1/2005 11:32:12 PM, William Stacy wrote:
>The redo is complicated by the fact that they are drilled rimless. If
>you stick with that frame, I'd ask for an upgrade to Trivex. They might
>let you off with the difference in price between the 2 materials. If
>not, then at least ask for a discounted redo. You can't really redo them
>in standard plastic unless you change to a grooved or standard mounting.
>
>If you are willing to change frames, you might get by with just the cost
>of the frame. Get creative and don't be bashful. Remind them that they
>didn't warn you that the ABBE value (amount of chromatic aberration) of
>polycarb is worse than just about any other lens material in the world.
> If they don't offer (or can't get) Trivex, why not???
>
>w.stacy, o.d.
>
>Charles wrote:
>
>> What do you think a fair policy is regarding a change from poly to CR-39 as
>> far as paying for it? Should I have to pay the whole bill for the new lenses?
>> I doubt they'll be willing to pay the entire bill themselves since they
>> didn't do anything wrong exactly. I also doubt that they'll even agree that
>> the poly could be the problem. I suspect I'll get a few eye rolls before it's
>> done ("oh, you read about it on the internet. I see..."). Until I read this
>> NG I had no idea there were so many options for material. I thought it was
>> glass, which nobody used anymore, plastic or poly. And the place I dealt with
>> never really mentioned that any of them were better optically...

>


 
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Charles
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      08-02-2005, 12:52 PM
Well, like I said, I was never totally happy in my last polycarb pair either.
I always had a very subtle "cross-eyed" feeling when looking straight ahead.
I realize this is all just speculation and could be something else entirely.
It was also the first time I went with anti-glare (Crizal), but I doubt that
would do it?

My prescription change was that I went up from 1.00 to 1.25 cylinder in one
eye. I believe that's it except for a minor change in axis on both eyes. They
seem hesitant to hand out the exact numbers. I know they will if I ask enough
times, but it seems that most people never ask.

On 8/2/2005 7:30:43 AM, "Dr. Leukoma" wrote:
>Since you had worn polycarbonate in the past, why indeed are you now
>having problems? Perhaps there was a significant prescription change,
>or change in the base curve of the lenses?
>
>
>DrG
>
>


 
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Dr. Leukoma
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      08-02-2005, 01:05 PM
Many pairs of polycarbonate lenses have been sold without complaint.
It is one of the most widely used ophthalmic materials because of its
thinness, light weight, relative impact resistance, and relatively low
cost. However, complaints like yours -- if the prescription is correct
-- are sometimes due to the higher aberrations (primarily chromatic) in
this material, which are more prominent as the prescription increases.

Since you mentioned a "cross-eyed" feeling when wearing your
eyeglasses, you should have your eye alignment checked as well by an
eye doctor.

DrG

 
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William Stacy
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      08-02-2005, 02:52 PM
Charles wrote:

>There's no reason not
> to stick with Crizal along with the plastic, right?
>


true


w.stacy, o.d.
 
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