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Thread: High Index prescribers: an aesthetics question?

  1. #1
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    High Index prescribers: an aesthetics question?

    I'm a regular consumer about to purchase some new glasses, and was hoping to get some advice from those who prescribe high index lenses regularly.

    Currently I wear semi-rimless glasses, oval lenses, 1.67 index. OD sphere is -9, OS is -8.5. The lens width is 45. PD is 63. I bought these glasses five years ago, and was very happy with the ET of ~4.5mm.

    Anyway, my prescription has also worsened, to about OD -10.25, and OS -9.5. I was REALLY looking forward to ditching my semi-rimless and purchasing a new pair with full plastic rim, 1.74 index, Essilor. I've shopped 7 stores to find ONE pair that I liked. Picky, I know.

    Due to my wide face, however, the full-rim frame I have fallen in love with is bigger, with a lens width of 49. Its lenses are almost rectangular, not oval. I got away with a lens width of 45 on my previous pair because they were semi-rimless. I am estimating that because of the frame width and rectangular corners, the edge thickness at the corners may get to 7mm (does that sound about right?)

    My dilemma is: go with the frame I love with 7mm lens edges, or continue to search for a semi/rimless pair (what I am trying to get away from) that I can put 5.5?mm lenses in.

    I assume that rolling and polishing the edges will help.

    My questions to opticians: how have people reacted to their 7mm ET? Do they have regrets? Based on your experience, what would you advise? Your thoughts are MUCH appreciated!!!

  2. #2
    Bad address email on file QDO1's Avatar
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    Quote Originally Posted by paulc
    I assume that rolling and polishing the edges will help.

    My questions to opticians: how have people reacted to their 7mm ET? Do they have regrets? Based on your experience, what would you advise? Your thoughts are MUCH appreciated!!!
    Although rolling and polishing the edges will make the edge thickness lower, it makes the spectacles look awful from the front. I seriously recommend you ask for the minimum saftey bevel possible, and see what it looks like, if you dont like it, a lab tech can take more off later or polish. That wont be an option once the edge has been taken off. if the frame is rectangle, the edge thickness will show on the whole of the edge, not specifically the corner. the plastic frame will disguise most of it. You might have an issue with colour fringing with that lens, but you wont be able to tell until it is glazed, and you are wearing it

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    Quote Originally Posted by QDO1
    Although rolling and polishing the edges will make the edge thickness lower, it makes the spectacles look awful from the front. I seriously recommend you ask for the minimum saftey bevel possible, and see what it looks like, if you dont like it, a lab tech can take more off later or polish. That wont be an option once the edge has been taken off. if the frame is rectangle, the edge thickness will show on the whole of the edge, not specifically the corner. the plastic frame will disguise most of it. You might have an issue with colour fringing with that lens, but you wont be able to tell until it is glazed, and you are wearing it
    I agree, and i'll often dip the lenses for a split second into some dye to color the edges a bit. Helps camoflauge them. You can even "paint" the edges to match the frame. Sometimes this makes the frame look a bit thicker. Another consideration on going larger is the "caved in head" effect where to an observer who can see the side of your head through your lenses the side of your head appears displaced inwards. I vote for the smaller eyesize, but understand the desire for style...

  4. #4
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    I am with QDO1. The eye size should be ok if the frame is plastic. Minimal safety bevel is recommended and polishing is probably not a great idea to start with. A smaller frame is always recommended with your level of myopia (if single vision) so you should keep that in mind. Because of the index of the lens, I am sure that there will be an antireflective coating and that will help with the appearance. Semi-rimless would not be recommended for you because there is nothing to hide the thickness of your lenses.

    QDO1 - What do you mean by color fringing and glaze?

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    Master OptiBoarder ikon44's Avatar
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    be aware that you will not have much difference on edge thickness between 1.67 and 1.74, i think the optical qualities of the 1.67 are better than 1.74
    To find out what,s happening in the UK optical market:
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    Do keep in mind that the plastic full frame is going to conceal much of the edge thickness. You will see much less of the edge, most plastic type frames are 3-4 mm wide. Polish the edges...but don't roll 'em!

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    what is the bridge size for both frames?

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    Bad address email on file QDO1's Avatar
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    Quote Originally Posted by SpecialT

    QDO1 - What do you mean by color fringing and glaze?
    lenses with a poor abbe value have a tendancy to break up the light going through them in to separate colours. eg a white wall might have a blue and yellow edge to it, or colour fringe. roughy speaking the higher the pescription, and the more off axis, and the worse the ABBE value (dispersive value) the worse the colour fringing

    Glaze comes from glazing, which is cutting the round lens into the frame

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    Your new lenses in your new frame will only be 1.5mm thicker than your older pair, thats nothing to worry about, (it will be about 6.6 mm edge thickness on the new pair)

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    Master OptiBoarder spartus's Avatar
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    Quote Originally Posted by ikon44
    be aware that you will not have much difference on edge thickness between 1.67 and 1.74, i think the optical qualities of the 1.67 are better than 1.74
    Abbe values notwithstanding, my one patient that I've thus far switched from 1.67 to 1.74 claimed that the 1.74 was significantly "sharper" than the 1.67.

    And before you ask: Same RX, even the same frame. Obviously, your mileage may vary, but I thought it'd be worth mentioning.

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    Can someone do a quick measurement for me with a 1.74 "diagram"?

    First of all, much thanks to all the responses. Your points about minimal beveling are duly noted.

    I have a follow-up question though -- what makes edge polishing/rolling look poor from the front? Does it cause more peripheral "ringing" temporally or something? The high index lenses my optician showed me have ALL been polished, so I could not compare with the unpolished look.


    My second plea for help is:
    I was wondering if someone who had a 1.74 thickness "diagram" (sorry, have no clue what its really called) could take a few measurements for me. Unfortunately, the optician here does not have a graph for the 1.74 lenses yet and cannot give me good estimates of edge thicknesses for the two frames I am considering.

    My PD is 63.
    Frame 1 is 50-19, so to my untrained mind, that means 28mm from the center of my pupil to the temple edge.
    Frame 2 is 49-18, which would be 26.5mm to edge.

    Could someone compare the edge thickness results for 26.5mm vs 28mm from center on the 1.74 graph for about -10 diopters?

    Your help is MUCH appreciated!

  12. #12
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    1.74 index lens
    PD 63
    Rx -10
    Frame 50-19 = 7mm edge thickness
    Frame 49-18 = 6.4 mm edge thickness

    Thats only .6mm differance!

  13. #13
    ATO Member HarryChiling's Avatar
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    My calculations are:


    for the frame 50-19 assuming an ed=51 and the base=1 spherical lens

    1.74n with 1mm CT would be 6.78mm thick at the edge
    1.67n with 1mm CT would be 7.47mm thick at the edge

    for the frame 49/18 assuming an ed=50 and the base=1 spherical lens

    1.74n with 1mm CT would be 6.16mm thick at the edge
    1.67n with 1mm CT would be 6.76mm thick at the edge

    I choose the base and ed to give you a base line for comparison, if you have more accurate figures. You could use my calculator online

    http://www.harrychiling.com/equations/actualthick.html

    it will give you the thickness accurate to 0.05mm. I am working on a calculator for aspherics as well hope to have it up soon.
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  14. #14
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    Polishing is okay, it is the rolling that would look bad. Basically when the edges are rolled the back of the lens is flattened to make it look thinner from the side. It does that.

    However, from the front the flattened part shows a LOT and looks terrible.

    Are your glasses polished now? If you like it and it doesn't bother you then do it again. If you don't like how shinny it is you can get a satin polish. This looks much better then the thick white edge you will get without a polish but is softer and not as shinny.

    As for the thickness, .6 mm can make a difference. I have two lenses that I use to show thickness and polished edges. The high index one is less then a mm thinner then the other one but it definitely looks thinner.

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    OptiBoard Professional sharon m./ aboc's Avatar
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    Question polished edges

    Does anyone think that polishing edges on a rimless or semi rimless helps keep them from chipping? ( on CR-39, poly or high index) Or is it simply cosmetic?
    sharon

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