Page 2 of 2 FirstFirst 12
Results 26 to 36 of 36

Thread: Help troubleshooting Progressives with Prism

  1. #26
    sub specie aeternitas Pete Hanlin's Avatar
    Join Date
    May 2000
    Location
    Hickory Creek, TX
    Occupation
    Lens Manufacturer
    Posts
    4,917
    Love reading threads like this- nice to know there is still a wealth of dispensing knowledge out there!

    One more consideration from the design perspective (based on my own dispensing experience)... I found relatively "hard" designs work well for patients with prism, because these designs tend to have a better defined "sweet spot" which a.) creates a "locator" for the eyes and b.) allows the patient to describe any misalignment of the sweet spots (as was noted in the OP).
    To be honest, the best results I achieved for patients with prism were with the ultimate in "hard" designs- blended bifocals (let the flaming begin :^). By adjusting the fitting height and inset, I could usually provide very comfortable distance and near vision without a line (and, at least in my experience, intermediate vision is always a crap shoot for these patients anyway). With a few exceptions, progressive designs challenge binocular vision anyway- and someone with prism doesn't need additional challenges (IMO). If the patient did a ton of work at the computer, I'd recommend and fit blended lenses with the intermediate entered as the distance script and half the ADD for near (even for patients without prism, this set-up works great for computer lenses).

    Disclaimer- Essilor employee... If I were selecting a lens from the Varilux portfolio for the scripts mentioned in this thread, it would be either a traditional Varilux Comfort or a Varilux Comfort DRx (most likely the former) in 1.60. While I love multi-surface designs, I agree with sharpstick777 that this amount of prism might be better suited to a single surface design.
    Pete Hanlin, ABOM
    Director Technical Marketing
    Essilor of America

  2. #27
    Ghost in the OptiMachine OptiBoard Silver Supporter Quince's Avatar
    Join Date
    Jan 2016
    Location
    Sebago ME
    Occupation
    Optical Laboratory Technician
    Posts
    656
    Good to know about the preference for hard designs. I will keep that in mind.

    Personally, I love the Duo. I've also had really good luck using them for PAL nonadapts or patients needing temporary multifocals. We've also had success with using either the Duo or anti-fatigue designs as PAL training wheels.

    I try and get as much of an understanding of these kinds of concepts as I can because I am seeing it from all sides. As a surfacing tech and optician I often have the upper hand of lab knowledge assisting my ability to fit patients, but this one had me stumped.

    Won't be the last time!

    And if I didn't like it, I'd be in the wrong field
    Have I told you today how much I hate poly?

  3. #28
    One eye sees, the other feels. OptiBoard Gold Supporter
    Join Date
    Jul 2002
    Location
    Wauwatosa Wi
    Occupation
    Dispensing Optician
    Posts
    4,535
    Quote Originally Posted by Pete Hanlin View Post
    Love reading threads like this- nice to know there is still a wealth of dispensing knowledge out there!

    One more consideration from the design perspective (based on my own dispensing experience)... I found relatively "hard" designs work well for patients with prism, because these designs tend to have a better defined "sweet spot" which a.) creates a "locator" for the eyes and b.) allows the patient to describe any misalignment of the sweet spots (as was noted in the OP).
    To be honest, the best results I achieved for patients with prism were with the ultimate in "hard" designs- blended bifocals (let the flaming begin :^). By adjusting the fitting height and inset, I could usually provide very comfortable distance and near vision without a line (and, at least in my experience, intermediate vision is always a crap shoot for these patients anyway). With a few exceptions, progressive designs challenge binocular vision anyway- and someone with prism doesn't need additional challenges (IMO). If the patient did a ton of work at the computer, I'd recommend and fit blended lenses with the intermediate entered as the distance script and half the ADD for near (even for patients without prism, this set-up works great for computer lenses).

    Disclaimer- Essilor employee... If I were selecting a lens from the Varilux portfolio for the scripts mentioned in this thread, it would be either a traditional Varilux Comfort or a Varilux Comfort DRx (most likely the former) in 1.60. While I love multi-surface designs, I agree with sharpstick777 that this amount of prism might be better suited to a single surface design.
    Pete,

    From my experience, and from consultations with other experts, the harder design PALs were the design of choice for the high astigmatic Rxs, where the prescribed (edit-astigmatism) would interfere less with the unwanted astigmatism of the PAL design, resulting in less deformation of the corridor and near zones. The extra wide near zone helped also. This was before we had Zeiss and Rodenstock atoric PALs, presently the surface design (atoric/optimized) of choice for moderate to high astigmats.

    I believe the only advantage of a hard design with prism Rxs is from the increased near zone width, improving near performance when the lens was not fit optimally, that is, when not accounting for the eye turn from the prescribed prism.

    Your spot on with the use of 1.60 Varilux Comfort or New Comfort (standard corridor length) semifinished PALs for moderate to high values of prism (> 4∆ total), because it works, where free-form/optimized designs are almost always instant failures. I will occasionally use Trivex Physio where safety is a chief concern and the near vision sees light use or is shared with task SVNO eyeglasses.

    Best regards,

    Robert Martellaro
    Last edited by Robert Martellaro; 08-15-2017 at 06:54 PM.
    Roberts Optical Ltd.
    Wauwatosa Wi.
    www.roberts-optical.com
    ~~~~~~~~~~~~~~~~~~
    An expert is a man who has made all the mistakes which can be made, in a narrow field. -Niels Bohr

  4. #29
    OptiBoard Novice
    Join Date
    Oct 2017
    Location
    Ohio
    Occupation
    Optometrist
    Posts
    1

    Similar case

    Any advice appreciated for a patient who wants a PAL & transitions.
    -0.50 SPH add 250 5.5 BD 5.5 BO
    Plano-1.00x140 add 250 5.5 BU 5.5 BO
    Right orbit is 2mm higher

  5. #30
    One eye sees, the other feels. OptiBoard Gold Supporter
    Join Date
    Jul 2002
    Location
    Wauwatosa Wi
    Occupation
    Dispensing Optician
    Posts
    4,535
    Quote Originally Posted by Becca217 View Post
    Any advice appreciated for a patient who wants a PAL & transitions.
    -0.50 SPH add 250 5.5 BD 5.5 BO
    Plano-1.00x140 add 250 5.5 BU 5.5 BO
    Right orbit is 2mm higher
    Dispensed about 4 weeks ago, seen today for an additional pair with FT28s. I also made SVRO (sans prism) to go with the SVDO.

    -0.75 +1.00 x 105 7.5 OU 5.00 UP
    -0.75 +0.75 x 065 7.5 OU 5.00 DN
    Add +3.00

    Frame is 42mm eye 24 dbl B 30.5. I'll try to remember to get a photo of the unequal segment heights and increased inset of the forthcoming segmented multifocals.

    Client was previously wearing PALs with Fresnel OS, and SVRO without prism. Poor near and far VA. Significant improvement in vision with the above. IME, too much prism for a PAL, especially oblique prism, but if you must, use a well designed semifinished PAL, high Abbe materials, and position the optics in anticipation of the eyes deviating towards the prism apexes by .3mm per prism diopter.

    Hope this helps,

    Robert Martellaro
    Attached Thumbnails Attached Thumbnails 25 PD 01.jpg   25 PD 02.jpg  
    Last edited by Robert Martellaro; 10-18-2017 at 06:48 PM.
    Roberts Optical Ltd.
    Wauwatosa Wi.
    www.roberts-optical.com
    ~~~~~~~~~~~~~~~~~~
    An expert is a man who has made all the mistakes which can be made, in a narrow field. -Niels Bohr

  6. #31
    Master OptiBoarder OptiBoard Silver Supporter
    Join Date
    Mar 2012
    Location
    Maryland
    Occupation
    Dispensing Optician
    Posts
    1,456
    Robert who makes that frame you posted?

  7. #32
    One eye sees, the other feels. OptiBoard Gold Supporter
    Join Date
    Jul 2002
    Location
    Wauwatosa Wi
    Occupation
    Dispensing Optician
    Posts
    4,535
    Quote Originally Posted by Tallboy View Post
    Robert who makes that frame you posted?
    Eye Think Eyewear out of Chicago. NOS (new old stock) made in France. Stainless Steel. It's about the only way to find a "medical", non-urbanized (clean lines, simple colors) frame in this size (wide dbl, deep B, narrow A). If you run across anything like this give us a heads-up.

    Hope this helps,

    Robert Martellaro
    Roberts Optical Ltd.
    Wauwatosa Wi.
    www.roberts-optical.com
    ~~~~~~~~~~~~~~~~~~
    An expert is a man who has made all the mistakes which can be made, in a narrow field. -Niels Bohr

  8. #33
    What's up? drk's Avatar
    Join Date
    Mar 2004
    Location
    Ohio
    Occupation
    Optometrist
    Posts
    7,164
    and position the optics in anticipation of the eyes deviating towards the prism bases by .3mm per prism diopter.
    Robert, this is new to me. I'm not sure I agree, here, regarding direction.

    I can understand at some level, but will you break down your reasoning, please?

  9. #34
    Rising Star
    Join Date
    Feb 2016
    Location
    usa
    Occupation
    Dispensing Optician
    Posts
    78
    and position the optics in anticipation of the eyes deviating towards the prism bases by .3mm per prism diopter.
    Isn't the deviation away from the prism base?

  10. #35
    One eye sees, the other feels. OptiBoard Gold Supporter
    Join Date
    Jul 2002
    Location
    Wauwatosa Wi
    Occupation
    Dispensing Optician
    Posts
    4,535
    Quote Originally Posted by drk View Post
    Robert, this is new to me. I'm not sure I agree, here, regarding direction.

    I can understand at some level, but will you break down your reasoning, please?
    Quote Originally Posted by Kwill212 View Post
    Isn't the deviation away from the prism base?
    Fixed. I need a proofreader, especially after drinks before dinner, wine with dinner, and after dinner drinks.

    Best regards,

    Robert Martellaro
    Last edited by Robert Martellaro; 10-18-2017 at 10:46 PM.
    Roberts Optical Ltd.
    Wauwatosa Wi.
    www.roberts-optical.com
    ~~~~~~~~~~~~~~~~~~
    An expert is a man who has made all the mistakes which can be made, in a narrow field. -Niels Bohr

  11. #36
    One eye sees, the other feels. OptiBoard Gold Supporter
    Join Date
    Jul 2002
    Location
    Wauwatosa Wi
    Occupation
    Dispensing Optician
    Posts
    4,535
    Roberts Optical Ltd.
    Wauwatosa Wi.
    www.roberts-optical.com
    ~~~~~~~~~~~~~~~~~~
    An expert is a man who has made all the mistakes which can be made, in a narrow field. -Niels Bohr

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. free form progressives and slab off prism
    By Daniel Cunningham in forum General Optics and Eyecare Discussion Forum
    Replies: 2
    Last Post: 03-03-2007, 05:56 PM
  2. Need help troubleshooting my Mom's progressives
    By Happylady in forum Progressive Lens Discussion Forum
    Replies: 22
    Last Post: 08-27-2006, 06:52 PM
  3. Prism In Progressives
    By WorldVisionGuy in forum General Optics and Eyecare Discussion Forum
    Replies: 5
    Last Post: 08-05-2006, 01:47 PM
  4. Prism in Progressives
    By edKENdance in forum Ophthalmic Optics
    Replies: 1
    Last Post: 01-22-2006, 11:37 AM
  5. Prism in progressives
    By April_01 in forum General Optics and Eyecare Discussion Forum
    Replies: 12
    Last Post: 09-29-2004, 07:38 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
OptiBoard is proudly sponsored by:
Younger Optics, Carl Zeiss Vision Inc., Vision Equipment, Optitech USA and The Optical Group