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Thread: Lens to minimize indoors barrel distortion with -5D and Astigmatism

  1. #1
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    Lens to minimize indoors barrel distortion with -5D and Astigmatism

    I hope I could get good professional advice on choosing the right type of lenses for my case. Recently I had bad experience with local opticians (in Vancouver, Canada). Some of them don't even know refractive index of fancy-name lens they sell :-(

    My old glasses that I comfortably wore for six years were:
    -4.25 -0.25 135
    -4.00 -0.50 067

    Lenses: Seiko Ultra 1.60 AS, front surface aspheric, Abbe 42
    Frame: full-rim metal 51-16, B 26, pd 62

    The new glasses I recently got (after lots of trouble, prescription recheck and return of an improperly made pair):
    -4.75 -0.50 135
    -4.25 -0.75 063

    Lenses: Essilor 1.67 (from Costco), aspheric, Abbe 32
    Frame: rimless 52-18, B 30, pd 62

    The new glasses definitely give me sharper vision and they look great, but there is a significant "barrel distortion". It is not a problem in the center of view, however the distortion is very noticeable off-center. For example, when I watch large TV, the screen itself is rectangular, but room corners that are about one meter away from TV, look curved (lower parts of walls "bent" towards TV). If I turn my head to put room corner in the center of view, it will "straighten", but then TV would be "bent".

    This barrel distortion is not very noticeable outdoors, but it is quite unpleasant indoors, and especially in closed spaces such as small rooms and corridors. I did play with new glasses to see if a change in pantoscopic tilt and/or panoramic angle would make a difference, alas there is no improvement.

    At the same time, my old glasses produce only minor barrel distortion (when I use them to watch the same TV or to work in the same room). Therefore, I came to think that the distortion problem is caused by
    a) optical qualities of new lenses;
    b) higher diopters in my new prescription;
    c) new frame that has slightly bigger lens and longer bridge.

    From what I've read, to minimize barrel distortion, the following choices could be made:
    a) go with a lower index, i.e. 1.60 or 1.53 instead of 1.67;
    b) get double aspheric lenses, i.e. where both front and back surfaces are aspheric;
    c) select a frame that requires smaller lenses.

    I'm considering keeping my current new glasses for outdoor use and getting a second pair just for indoors / computer / TV use. Therefore, I'm not concerned about how this second pair would look, or how thick lenses would be, but I really want to achieve the best optical clarity (while keeping costs reasonable).

    So far I'm thinking about the following:
    1) Seiko 1.60 DA (double aspheric), based on positive experience with my old glasses.
    2) Trivex 1.53, however it seems that Trivex is not available in modern aspheric designs.
    3) "Computer lenses" made from CR39, but perhaps they are not for my diopters.

    My question is: what material and lens brand would you recommend in my case based on your professional experience?

  2. #2
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    I'm running out of the office in just a minute, so I'll address the specifics later (or I'm sure lots on here will as well). Distortion is an aberration that is a direct result of magnification changes as you move into the periphery. This is a factor of lens shape and thickness and has nothing to do with the abbe value or "quality" of the lens material. Prescription can affect this only insofar as it affects the thickness and curvature of the lens, and your new prescription in and of itself does nothing to positively affect your perception (in fact the increase in power could be seen as making it worse. That being said the change is minute enough for it to most likely not be a factor). What you're experiencing is most likely pincushion distortion as you are myopic.

    Managing this aberration is done by managing the curves and thickness, not so much ordering from a specific manufacturer (unless a specific manufacturer has some odd departure from Best Curve). Aspherics are one way to address this issue, though I see you've already gone down that road.

    What kind of shape are your frames? What is the vertex distance?
    "The Drizzle", ABOC-AC ... word to your mother.

  3. #3
    Master OptiBoarder
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    You bought your glasses from a cheap store that was founded as a company with nothing to do with optics... and you're having trouble? I for one am shocked. Now I'm sure were the bad guys for not helping you for free.

  4. #4
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    Can a mod come in and close this thread down. I'm sorry sir but this is a board for Opticians, not for consumers that want free advice. Best of luck with your issue.

  5. #5
    OptiBoard Professional OptiBoard Bronze Supporter
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    I had the same dentist for 20 years until he retired. Stayed loyal to my mechanic as well. If you had a pair of glasses you were happy with, why jump ship? If price was your motivation, seems like you've traded dollars for hassle. If they're still in business, go back to where you got the first pair.

  6. #6
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    Pay a professional who understands opthalmic optics to be fit well and use quality products with skill. Problem solved.

    Next?

  7. #7
    Master OptiBoarder OptiBoard Silver Supporter
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    This is not a forum for consumers but for professionals within the Optical Community. You need a face to face experience with an Ophthalmic Optician.
    I didn't attend the funeral, but I sent a nice letter saying I approved of it. Mark Twain

  8. #8
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    This board is not for consumers. Please close this thread.

  9. #9
    Forever Liz's Dad Steve Machol's Avatar
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    As per the forum rules you agreed to when you registered:


    "This forum is for Eyecare Professionals. Consumers are not allowed to post on the Board, although they can read posts and search topics."


    All the professional Opticians on this site would love to help you solve your problems or answer your questions about your eye care and eyewear needs. But vision and visual solutions can have thousands of correct as well as incorrect answers.


    We care about your vision and visual needs so strongly that we must advise you to seek a professional in the eye care field. Only with in-person evaluation can you truly get a proper diagnosis. You PD and powers are simply not enough information to give you any kind of advice other than speculation. We are sure that you want the best in eye care, as we want for you. Please seek out someone that you can discuss your issues with in person.


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