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Thread: Help with replicating lenses from old specs

  1. #1
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    Help with replicating lenses from old specs

    I have a pair of glasses made with 1.67 aspheric. The spectacle Rx is OD: -4.75-0.25x170 OS: -5.00. The lens clock readings are as follow:

    OD: F1 +1.25@090 and +4.00@180 F2 -5.50@090 and -8.00@180

    OS: F1 +1.75@090 and +4.75@180 F2 -6.25@090 and -8.75@180

    I would like to make the same spectacle prescription with the same lens material, and make the new glasses look as thin as the old pair. I have a few questions:

    1) why are there toric surfaces on both sides of both lenses? From what I've read, the front surface of modern lenses (the pair of glasses is only 7 years old) should be spherical while the back surface would be the spherocylinder surface. The fact that both lenses have toric surfaces on both sides leads to me to believe that it was done on purpose; henceforth, the lenses are not warped. Am I correct?

    2) why do the numbers off of the lens clock not equal the spectacle refraction? Is it because the lens clock is designed to read n=1.53, and so it is reading low with the 1.67? If so, then is there a conversion factor? How would I accurately replicate the curves?

    3) how would I order the new lenses for the new glasses (the frame is approximately the same size and shape) so that the new lenses look as thin and flat as the current ones?

    Please help! Thanks!

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    Don't use a lens clock to measure an aspheric surface. It will only confuse you.

    If you want to match the lens, simply order a 1.67 aspheric from your lab, and specify that you want a certain center thickness. Let the lab worry about the rest.

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    Thanks for the reply. I have another question. If I simply order a 1.67 aspheric and specify CT, then what about perceptual distortions that will be induced by the new lenses that may have a different BC than the previous pair? The client is quite set in his ways and quite particular. I'm not sure if he'll be okay with what would be typical adaptation responses. Also, would order the thinnest CT insure that I have a pair of glasses that will be as thin-looking as his current pair given that the new frames are only slightly bigger? Would I stand a better chance of replicating the look and "see" of his old glasses if I'm able to specify the same BCs, CT, etc... of his old Rx?

    Thanks for the help.

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    Perception is everything lol!

    The problem though, is, that if you don't know who manufactured the original lenses, there is no way to determine what brand they are, or if they were custom cast/ground.

    Because of the relatively small OC central area on an aspheric, there really is no good way to measure the curve/sag unless you have a very small sag guage. Have you tried dotting the OC's on both lenses, then putting the lens clock center pin on the OC mark and reading the base curve?

    BTW, what is the Rx?

  5. #5
    ABOM Wes's Avatar
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    It sounds like those old lenses are warped.
    Wesley S. Scott, MBA, MIS, ABOM, NCLE-AC, LDO - SC & GA

    “As our circle of knowledge expands, so does the circumference of darkness surrounding it.” -Albert Einstein

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    Wes,

    Would both lenses be warped. Maybe they are, but I just find it strange that both of them are that way. It leads me to believe that they were made that way on purpose - maybe to get the flattest profile? Here is the issue with the patient. He has these old glasses - loves the way he sees out of them and how the glasses themselves look. He has had new glasses made also with 1.67 aspheric lenses. However, the new lenses are much thicker on the edge than his old ones, the new ones also minify his eyes a lot more and everything looks smaller in space to him out of the new ones. So, in summary, the new ones are thicker, make his eyes look smaller and makes things out in space look smaller. He does not like it. When I take the BC measurements on the new glasses, they are as follow:

    OS: F1 +1.00@090 and +2.25@180 F2 -5.25@090 and -7.00@180 OD: F1 +0.75@090 and +3.50@180 F2 -4.50@090 and -7.00@180

    I believe that the reason he has more minification of his eyes and minification of space through his new glasses is because he has less (+) power on the front surface curves of his new glasses compared to his old glasses (see earlier post on this thread). Am I correct about that? Also, would ordering the same exact curves help me make the new glasses the same as the old? However, since lens clocks read too low for indices > 1.53, how would I do that correctly?

    As you can see, I am in a conundrum. I'm stuck. Any suggestions?

  7. #7
    ABOM Wes's Avatar
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    Long A/ short B glasses tend to be warped slightly by chuck pressure, causing them to be edged longer than desired. Then, when mounted, pressure from the frame on the too-long lenses will warp them just the way you describe.

    Also, it sounds like on the new glasses that there is less warping than in the old pair. More warpage equals more meridonal magnification. Your pt has probably gotten used to this. He will have to get used to something new.

    Also, If the new frame's A is larger than the old they will be thicker.
    Wesley S. Scott, MBA, MIS, ABOM, NCLE-AC, LDO - SC & GA

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    Master OptiBoarder MakeOptics's Avatar
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    Could be an atoric lens or custom job, just a thought. Either way you are not going to have the necessary tools to correctly clock those curves if they are aspheric curves, and if the Rx changed the perception will still change.

    They could also be shape lenses designed specifically for that patients visual scenario, good luck.

    1.67 is also more susceptible to heat so both lenses being warped could be a realistic consideration, although to that degree would be amazing.
    Last edited by MakeOptics; 07-13-2012 at 10:19 PM.

  9. #9
    ABOM Wes's Avatar
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    Hey, welcome back!
    Quote Originally Posted by PhiTrace View Post
    Could be an atoric lens or custom job, just a thought. Either way you are not going to have the necessary tools to correctly clock those curves if they are aspheric curves, and if the Rx changed the perception will still change.

    They could also be shape lenses designed specifically for that patients visual scenario, good luck.

    1.67 is also more susceptible to heat so both lenses being warped could be a realistic consideration, although to that degree would be amazing.
    I'm basing my statements on the assumption that this is a sv rx, and that even aspherics have a radially symmetric aspheric front curve, meaning the asphericity is the same in all meridians. If this were a high cyl rx, I can see a theoretical use of a bitoric/atoric type lens, but...

    What's more likely?

    A genius optician designed bitoric lenses for a primarily spherical spectacle Rx of
    OD: -4.75-0.25x170 OS: -5.00.

    or

    Some rookie lab tech bungled a job.

    I'm going with Occam's razor on this one.
    Wesley S. Scott, MBA, MIS, ABOM, NCLE-AC, LDO - SC & GA

    “As our circle of knowledge expands, so does the circumference of darkness surrounding it.” -Albert Einstein

  10. #10
    One eye sees, the other feels OptiBoard Silver Supporter
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    Quote Originally Posted by Neophyte Optician View Post
    I would like to make the same spectacle prescription with the same lens material, and make the new glasses look as thin as the old pair. I have a few questions:
    I think it was Augen who had an atoric front curve (about .75 DC) awhile back, but what you have is a warped lens.

    order the thinnest CT insure that I have a pair of glasses that will be as thin-looking as his current pair
    Too thin, and the lens might warp, the AR might fail prematurely, and might not be safe (bypassing the manufacturers recommendations).

    the new ones also minify his eyes a lot more and everything looks smaller in space to him out of the new ones.
    Reduce minification by fitting close, the lens bevel as far forward as possible, with a flatter BC. Clean up the on and off-axis power error and oblique astigmatism on a free-form manufacturing platform with capable software.

    Quote Originally Posted by Wes View Post
    What's more likely?

    A genius optician designed bitoric lenses for a primarily spherical spectacle Rx of
    OD: -4.75-0.25x170 OS: -5.00.
    Yeah, an insane genius. Let's get him!
    Science is a way of trying not to fool yourself. - Richard P. Feynman

    Experience is the hardest teacher. She gives the test before the lesson.



  11. #11
    Master OptiBoarder optical24/7's Avatar
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    ..
    Last edited by optical24/7; 07-14-2012 at 06:32 PM. Reason: b-cause me stuupid...

  12. #12
    ABOM Wes's Avatar
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    Assuming spherical crown glass, (which its not) I get:
    Od -4.00-.25
    Os -4.00-.50
    I think you used a number-line difference instead of algebraic summation. A +4 front curve and a -8 back curve gives -4 power. Check against the rest of the warped readings and you'll get what I posted above.
    The clock numbers aren't correct due to asphericity and warpage, and would still need to be index-compensated, but they're close enough that I can tell the lenses are warped.
    Last edited by Wes; 07-14-2012 at 06:39 PM.
    Wesley S. Scott, MBA, MIS, ABOM, NCLE-AC, LDO - SC & GA

    “As our circle of knowledge expands, so does the circumference of darkness surrounding it.” -Albert Einstein

  13. #13
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    Quote Originally Posted by Wes View Post
    It sounds like those old lenses are warped.
    I second the motion!

    I, too, think the lenses are warped, and your new ones are well on the way to the same graveyard of optics. Too thin of a lens, will mean a real unequal pressure on the lens edges, especially in a rectangle frame, with the OC well above midpoint. What is the CT of the old, and the new lenses?

    Vertex is critical for minimum diminution of image, as is frame shape, and area.
    Last edited by uncut; 07-14-2012 at 08:23 PM. Reason: brain warp due to heat wave....very abberated...forgot Q mark.
    Eyes wide open

  14. #14
    Master OptiBoarder optical24/7's Avatar
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    OK, I left my lab hat at work, gotcha.
    Last edited by optical24/7; 07-14-2012 at 06:29 PM.

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    (an aside, remembering back in the day...)

    We used to make anisekonic (sp?) bitoric lenses for quite a number of docs before our calculator up and died (the program was specifically written for an ancient TI desktop calculator/computer that used magnetic cards and we couldn't find anyone who had a reader and could convert the program for us to another platform). The lenses were all bitoric (with crossed cylinders) in glass, usually made as laminates to ensure that we could spin the lens elements to achieve the proper power. It was a futzy picky process and I was glad when we could no longer make them. They were a real pain in the butt.

  16. #16
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    They're either warped or if you didn't put the center pin of the lens clock right at the OC, you will get skewed readings.

    Why order this custom??? Just order stock. Stock will not lower your chance of success.

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    Sola use to make an Atoric 1.67 lens with UTMC..brand name ViZio.

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    Quote Originally Posted by Neophyte Optician View Post
    So, in summary, the new ones are thicker, make his eyes look smaller and makes things out in space look smaller. He does not like it.
    Beyond what I recommended above, one might also consider Hoya's Nulux EP (1.70) and Nikon's Seemax. Both are bi-aspheric/atoric, and might be just the the edge you need to put your client in a happier place.
    Science is a way of trying not to fool yourself. - Richard P. Feynman

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    Here is the issue with the patient. He has these old glasses - loves the way he sees out of them and how the glasses themselves look. He has had new glasses made also with 1.67 aspheric lenses. However, the new lenses are much thicker on the edge than his old ones, the new ones also minify his eyes a lot more and everything looks smaller in space to him out of the new ones. So, in summary, the new ones are thicker, make his eyes look smaller and makes things out in space look smaller. He does not like it.
    Ok, let's back up a moment here...

    Your patient is happy with his obviously warped lenses and has grown accustomed to them.

    May I respectfully suggest that you ask him to have a new eye exam? As I see it, you are trying to reinvent the wheel, using a wheel as a guide that is not true and not centered. This is a recipie for disaster. I've always had my doubts about making new lenses by reading the powers off the old lenses, I much prefer to go off the Doctor Rx instead.

  20. #20
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    Quote Originally Posted by MikeAurelius View Post
    Your patient is happy with his obviously warped lenses and has grown accustomed to them.
    Neophyte says his client's chief concerns are increased minification (both cosmetic and visual), and increased edge thickness with his new lenses. I've been concentrating on reducing or eliminating those symptoms. I'm not convinced that these symptoms are related to warped lens surfaces. Instead, I believe they are more consistent with lens positioning and base curves. Hopefully, Neophyte will follow up with more details and results.
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    Quote Originally Posted by Robert Martellaro View Post
    Neophyte says his client's chief concerns are increased minification (both cosmetic and visual), and increased edge thickness with his new lenses. I've been concentrating on reducing or eliminating those symptoms. I'm not convinced that these symptoms are related to warped lens surfaces. Instead, I believe they are more consistent with lens positioning and base curves. Hopefully, Neophyte will follow up with more details and results.
    Robert, you have hit the nail on the head regarding the client's chief concern. Increased minification and increased edge thickness are the primary concerns. The patient has had a new eye exam, and the prescription hasn't changed significantly from his old pair. I'm not sure if I'm correct, but my hunch was that the client's concerns revolve around the base curves of his old Rx. That is why I was asking about BC readings, etc... However, from the sounds of all of the replies (and thank you much for all the input), it sounds like I'm going to have a difficult time placating this particular client.

    This is what I think I'm going to do (please tell me whether you all think this is a good idea):

    1) Order Rx in 1.67 aspheric with an ARC
    2) Match the BC reading of the flattest BC on each old lens (while telling the lab that I took it with a lens clock, but that it's for a 1.67 aspheric lens)
    3) Request 1.0 CT
    4) Reduce the vertex distance of the glasses on the client's face
    5) Cross my fingers and toes that it works out.

    Thoughts?

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    Quote Originally Posted by Neophyte Optician View Post
    Robert, you have hit the nail on the head regarding the client's chief concern. Increased minification and increased edge thickness are the primary concerns. The patient has had a new eye exam, and the prescription hasn't changed significantly from his old pair. I'm not sure if I'm correct, but my hunch was that the client's concerns revolve around the base curves of his old Rx. That is why I was asking about BC readings, etc... However, from the sounds of all of the replies (and thank you much for all the input), it sounds like I'm going to have a difficult time placating this particular client.


    This is what I think I'm going to do (please tell me whether you all think this is a good idea):

    1) Order Rx in 1.67 aspheric with an ARC
    2) Match the BC reading of the flattest BC on each old lens (while telling the lab that I took it with a lens clock, but that it's for a 1.67 aspheric lens)
    3) Request 1.0 CT
    4) Reduce the vertex distance of the glasses on the client's face
    5) Cross my fingers and toes that it works out.

    Thoughts?
    Not sure there is too much more that you can do. There are sometimes when you are not going to meet their expectations because the patient wants something impossible. I hope that it works out, because it's obvious you are going above and beyond to satisfy your patient. Good luck!

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    Quote Originally Posted by Neophyte Optician View Post
    Robert, you have hit the nail on the head regarding the client's chief concern. Increased minification and increased edge thickness are the primary concerns. The patient has had a new eye exam, and the prescription hasn't changed significantly from his old pair. I'm not sure if I'm correct, but my hunch was that the client's concerns revolve around the base curves of his old Rx. That is why I was asking about BC readings, etc... However, from the sounds of all of the replies (and thank you much for all the input), it sounds like I'm going to have a difficult time placating this particular client.


















    This is what I think I'm going to do (please tell me whether you all think this is a good idea):

    1) Order Rx in 1.67 aspheric with an ARC
    2) Match the BC reading of the flattest BC on each old lens (while telling the lab that I took it with a lens clock, but that it's for a 1.67 aspheric lens)
    3) Request 1.0 CT
    4) Reduce the vertex distance of the glasses on the client's face
    5) Cross my fingers and toes that it works out.

    Thoughts?
    6) Exude confidence and increase CT to 1.4mm for stability. This may not eliminate warping, but will help delay the onset.
    Eyes wide open

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    Quote Originally Posted by Neophyte Optician View Post
    1) Order Rx in 1.67 aspheric with an ARC
    1.70 should be on the table, if you can get it.

    2) Match the BC reading of the flattest BC on each old lens (while telling the lab that I took it with a lens clock, but that it's for a 1.67 aspheric lens)
    That might require semi-finished, and that locks you in to the manufacturer's recommended BC (and for good reason- go flatter or steeper than recommended, especially with aspherics, and the off-axis optics will be trashed). You might have more BC latitude with optimized (Zeiss Individual, Shamir Autograph, etc.) lenses, but finished lenses might be hard to beat, except for the quality of the ARC.

    3) Request 1.0 CT
    Possible with finished lenses only, I think. Is Hoya's Nulux EP available in finished form? With a thin CT.?

    4) Reduce the vertex distance of the glasses on the client's face
    The most important factor for this example (image size), and very frame dependent.

    5) Cross my fingers and toes that it works out.
    This should work, so no voodoo required. However, and Mike alluded to this when he mentioned iseikonic lenses, if the summation of front and back cylinders is increasing the magnification (or decreasing the minification), then that might be impossible to reproduce.
    Science is a way of trying not to fool yourself. - Richard P. Feynman

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  25. #25
    Master OptiBoarder OptiBoard Silver Supporter Jubilee's Avatar
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    I was thinking 1.70 as well. Vision Ease thindex is readily available if you aren't in a Hoya friendly area.

    Another double-aspheric option is the Seiko MaxVue in 1.67
    "Some believe in destiny, and some believe in fate. But I believe that happiness is something we create."-Something More by Sugarland

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