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Thread: Generic CR-39 1.74 index lenses vs Essilor 1.74?

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    Generic CR-39 1.74 index lenses vs Essilor 1.74?

    I am getting some 3 year old lenses replaced and have the choice of paying in the region of $150 for CR-39 1.74 index lenses from selectspecs.com or around three times as much for my local optician to put in Essilor's 1.74 index lenses. Selectspecs says they manufacture their own lenses, and that they have an Abbe value of 33 and specific gravity of 1.46. With a prescription of -9.25, do you think that there will be any visible difference in the thickness the lenses? Is there any other difference that I should be aware of...?

    Many thanks for any help you can give.

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    Old Optician to New OD Aarlan's Avatar
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    CR-39 has an index of 1.498


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    Quote Originally Posted by arthur
    I am getting some 3 year old lenses replaced and have the choice of paying in the region of $150 for CR-39 1.74 index lenses from selectspecs.com or around three times as much for my local optician to put in Essilor's 1.74 index lenses. Selectspecs says they manufacture their own lenses, and that they have an Abbe value of 33 and specific gravity of 1.46. With a prescription of -9.25, do you think that there will be any visible difference in the thickness the lenses? Is there any other difference that I should be aware of...?

    Many thanks for any help you can give.
    Before this errupts I will just say that you should not purchase your glasses online. A licensed optician is needed, especially with your prescription, to ensure that the products is distributed properly. If the glasses are not fit properly then the vision will not be the crispiest.

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    Old Optician to New OD Aarlan's Avatar
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    Pro's of getting your eyeglasses through a local professional:

    -will properly measure to ensure proper fitting of your lenses
    -will ensure glasses are properly made by the laboratory
    -will properly adjust your glasses to you so they are comfortable and snug
    -will gladly adjust the glasses as needed over the next few months/years as necessary
    -will honor any manufacturer's warrantees on Lenses and Frames if necessary (some up to 2 years on the lenses!)
    -will help you select eyewear that best suits your features and dimensions
    -Will normally perform minor repairs when necessary
    -will contribute their knowledge and experience to your benefit.

    Con's of obtaining your eyeglasses online
    -no guarantee of proper manufacture
    -measurements are apparently not terribly important to them...from selectspecs site,
    'If the Buyer does not provide SelectSpecs with their particular pupillary distance/PD we will use an average PD of 63mm in making your bifocal and single vision distance spectacles. A PD of 60mm will be used for single vision reading spectacles. ' this would result in a pair of glasses that would not pass the minimum requirements for accuracy where we are located. A professional would probably have his/her credentials yanked if they were so careless in the fabrication of a medical device.
    -no warrantee or guarantee on lenses or frame in most cases, so if they are damaged or are defective...too bad, you have to purchase another pair.
    -If they are not properly fit, adjusted or selected...too bad.
    -If you seek out the expertise of a professional to help you in fixing, repairing, adjusting, or verifying your new spectacles, you will probably be charged an exorbitant fee...and rightly so, since at that point you would have a better idea why a knowledgeable, experienced professional is needed in the first place, and why the their added cost is probably worth it.

    AA

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    Old Optician to New OD Aarlan's Avatar
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    Just out of curiosity, would you mind sharing your vocation with us?

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    At least this site won't fit progressives or prescriptions with prism. I cringe when I see sites fitting progressives over the internet.

    Like the others have said, if you wear a -9.50 then you really need to see a local optician.

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    Quote Originally Posted by Happylady
    At least this site won't fit progressives or prescriptions with prism. I cringe when I see sites fitting progressives over the internet.

    Like the others have said, if you wear a -9.50 then you really need to see a local optician.
    The funny thing though is I priced out a couple of frames, and they are not cheap. I am not considered a price leader in the city, and I am very competitive with them. Plus, I know I offer a much better AR (and service).

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    Always remember

    The sourness of poor quality last long after the sweetness of low price.

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    Many thanks for your responses. I suspected that the CR-39 description was inaccurate and one of their people has just confirmed that their 1.74 index lenses are indeed not made of CR-39, saying instead that they were made of an unspecified other plastic.

    I will not quibble with you on the point that there are, of course, significant advantages to ordering my lenses locally. That said, I am not entirely convinced of the value of having a "local" optician, seeing as I hardly spend 3 months of each year in NY, with the rest of my time being scattered in other states and abroad. As I already have a fresh prescription (PD measurement and all) from my ophthalmologist, and have frames already, I am open to the possibility of paying a third of the price for the lenses and just having them fitted wherever I happen to be, as long as the lenses themselves are decent.

    This is what was hoping you might help me with -- is the Abbe value and specific gravity cited for this lens any good? Are there likely to be significant differences in the thickness of 1.74 index lenses made by different manufacturers? In their other qualities?

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    Quote Originally Posted by arthur

    This is what was hoping you might help me with -- is the Abbe value and specific gravity cited for this lens any good? Are there likely to be significant differences in the thickness of 1.74 index lenses made by different manufacturers? In their other qualities?
    this is not like buying a computer where you just check out which has the juciest technical specification.

    The abbe value measures the amount of chromatic abberation you will get with a particular material.So wether it is good or bad depends a lot on your current spectacle material.Dont be a cheapskate go and see a professional optician, with an prescription like yours,buying online makes no sense at all .:hammer:
    To find out what,s happening in the UK optical market:
    http://theOptom.com

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    [QUOTE=
    This is what was hoping you might help me with -- is the Abbe value and specific gravity cited for this lens any good? Are there likely to be significant differences in the thickness of 1.74 index lenses made by different manufacturers? In their other qualities?[/QUOTE]


    Yep...just what I thought.
    ...just your average, run of the mill, consumer.


    See, it just doesn't fit. Even if you are just an average consumer with above average questions, most people with that kind of IQ wouldn't even consider ordering online.

    Your concerned about thickness ? Why?
    Your concerned about abbe values? Why?
    Your concerned about saving 3X of what?

    And your a -9.25 ? I'm sorry, I've never known a myope that high that would trust his vision to an online store.

    I'm not buying it.

    Dp you really want to save some money...

    Have you considered glass photogray? They take the place of two pairs of glasses, and if you get 3.0 industrial centers, they'll last you a lifetime. Now that's saving some serious $$$$ !

  12. #12
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    Quote Originally Posted by Johns
    Yep...just what I thought.

    I'm not buying it.

    Dp you really want to save some money...

    Have you considered glass photogray? They take the place of two pairs of glasses, and if you get 3.0 industrial centers, they'll last you a lifetime. Now that's saving some serious $$$$ !
    Now you got right listen to john he knows what he is talking about Righ ON!!!!!

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    Wake up Optiboarders!

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