Gee, from the tone of these posts, it sounds like polycarbonate is a
wildly inadequate lens material. It is anything BUT inadequate.
But, the question is whether you want to talk theory, or practice?
Here's theory:
The negatives have been *well* documented, so I won't repeat them.
While it is true that polycarbonate displays the most significant
aberrations of any commonly used material, it does have a number of
benefits including cost and toughness/shatter resistance. It is also,
as was stated earlier, very good for rimless and drill mount
applications.
Here's practice:
Polycarbonate falls into the "mid-index" range...producing neither
high index (thin), nor low index (thick) lenses. There are a number
of different formulations, but the normal ones all fall into the 1.56
or 1.57 range.
Polycarbonate is used as the default lens material for many of the
online vendors, and many of the B/M shops as well. At some shops they
even charge a premium for it, due to its benefits...shatter resistance
(safety lenses) being one of the most obvious. Many, many, MANY of us
wear polycarbonate lenses, and do just fine. My own glasses use poly,
and came from Zenni Optical...in fact my favorite pair was only $8.
The glasses and lenses are great.
Now it's time to talk about your prescription.
Your prescription is not strong at all. In fact, by the standards of
many on this forum, it's practically nothing! You're not blind. You
won't have coke bottles. It's not going to be disfiguring. There, it
needed to be said.
Additionally, at your level of correction, any optical aberrations
introduced by any normal material *including* polycarbonate would be
so slight, as to be *practically* irrelevant.
Pick what you want. Heck...at these prices, pick several!
If it helps you, then look at it from the other direction. What's the
worst that could happen? You could skip a couple of lattes and buy
some glasses. If it doesn't work out then you could donate them to
the Lion's Club. The Lion's Club benefits, and you end up with a tax
deduction!
Not much of a risk, huh? :)
-- Chuck Knight
On Fri, Oct 23, 2009 at 8:47 PM, EdT <[email protected]> wrote:
>
> Lorena, your optometrist is pulling your leg !
>
> Your prescription is relatively light, even with the "lowest
> index"(thickess) 1.5 lens there would not be a significant
> difference. Polycarbonate lens have the worst optical properties of
> all lens materials and are usually in the 1.57 to 1.59 mid to high
> index lens category, but they do offer the advantage of being impact
> resistant if you use your glasses for sports.
>
> The standard CR39 mid index 1.56 lens is more than enough for your
> prescription, going to a higher index lens is waste of money for such
> a low power prescription and you would not notice barely any
> significant thickness difference between mid to high index lens.
>
> On Oct 22, 7:16 am, Lorena <[email protected]> wrote:
>> Hi,
>>
>> I recently went to the optometrist for my annual exam and got my
>> prescription. When I went to pick out glasses though my jaw hit the
>> floor when i saw the prices. So I decided I was going to buy online.
>>
>> I have a relatively stronger prescription need in my left eye as
>> compared to my right and my local optician said I would need to
>> purchase polycarbonate lenses to avoid extremely thick lenses and so
>> that the lenses would be made as close in width to each other as
>> possible.
>>
>> Is this true?
>>
>> Also considering my prescription: my right eye is -.50/-.50/012 and my
>> left eye is -1.25/
>> -1.0/172, would there be a substantial thickness difference if i went
>> with the regular plastic lenses as opposed to the polycarbonate or
>> even a high index glass lens.
>>
>> Thanks in Advance.
>
> >
>
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