Your sphere isn't particularly strong...your astigmatism isn't too bad.  All
in all, a very "ordinary" prescription, judging by what we deal with on this
list.

So, let's deal with your other question...lens thickness.  Index is a term
referring to the refractive index of the lens material...higher numbers make
for thinner lenses.  The difference is most noticeable in thick/strong
lenses.  BUT, the difference on a relatively normal prescription isn't that
enormous.  Usually it's a difference of around 10-20%.  On a lens that's an
inch thick, it's enormously noticeable...  Yours aren't that strong.

There's a lens thickness calculator that we usually refer people to, so they
can see the differences in their *own* prescription, themselves.  Let me
find that URL in the list archives...
http://www.opticampus.com/tools/thickness.php

Also, be aware that most of the online places use "medium index" lens
materials, like polycarbonate, by default...it's not considered an upgrade,
where we shop.

So, shop around.  At these online prices, you can *have some fun* with your
frames.  Some of the places sell them for $7 or $8 a pair!  Historically, I
always chose modest wire rimmed frames, until I finally chose some bold
plastic ones.  Why?  because I'd never had plastic, before.

Turns out, that they look good on me!  I've never received so many
compliments on any other "accessory."

     -- Chuck Knight

P.S.  BE SURE to get an accurate PD measurement.  It's the key to success
with online glasses, and the one part of the prescription that your doctor
*may* give you trouble with.  We've many discussions about this, and even a
few sample "scripts" of how to handle a difficult doctor, or where else to
go to get it measured.




On Mon, May 4, 2009 at 12:13 PM, PghGuy <[email protected]> wrote:

>
> I'm doing research for purchasing glasses online.  I last got glasses
> eight years ago (I know, too long) and am only now becoming familiar
> with the options for lenses and frames that are available.  I also
> don't know how much this prescription differs from my last one since I
> went to a different optometrist and don't have the last prescription
> with me.  Given my prescription, would lens upgrades such as
> polycarbonate or high index be a good idea to reduce the thickness or
> would it be okay to go with the lowest plastic offered?  At the moment
> I have polycarbonate lenses and they are adequately thin.  I read that
> high index is recommended for a prescription of -5.00 or higher but
> mine isn't quite that high.  I'll be getting metal frames with lenses
> perhaps 46-48mm in width and probably under 38mm in height.
>
> OD--Sphere:  -3.50; Cylinder:  -0.75; Axis:  136
> OS--Sphere:  -3.00: Cylinder:  -1.25; Axis:  074
>
> Would you consider this a "strong" or "abnormal" prescription in any
> way?
>
> Any advice would be appreciated.  Thanks a lot!
>
>
> >
>

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