Results 1 to 5 of 5

Thread: Plus power creeps into distance?

  1. #1
    OptiBoard Professional lab fly's Avatar
    Join Date
    Apr 2006
    Location
    Chicagoland
    Occupation
    Optical Wholesale Lab (other positions)
    Posts
    113

    Plus power creeps into distance?

    We have noticed for years that when we process a plus powered PAL, with a small B and a distance AOC of 12 or less that some of the plus power "creeps" up into the distance by an 1/8 or so. We have never had any offices or their patients complain but it is on all platforms. We have seen it on Zeiss, Shamir, IOT, and Seiko. I have a thought in my mind why it happens but does someone have a better scientific reason? Thanks

  2. #2
    OptiBoard Professional
    Join Date
    Jan 2017
    Location
    USA
    Occupation
    Dispensing Optician
    Posts
    195
    I have noticed when I order Shamir Auto2+ pals from one of our labs I will get a tiny bit of plus in the distance but when I order the same design from another lab we use the powers are usually spot on.

  3. #3
    Master OptiBoarder OptiBoard Silver Supporter lensmanmd's Avatar
    Join Date
    Oct 2016
    Location
    Maryland
    Occupation
    Optical Wholesale Lab (other positions)
    Posts
    1,178
    Are you providing POWs, or relying on avg calculations?
    I bend light. That is what I do.

  4. #4
    Master OptiBoarder
    Join Date
    Feb 2010
    Location
    ALBUQUERQUE
    Occupation
    Optical Laboratory Technician
    Posts
    422
    Induced power as you described as .12 is typical if lens power is a strong plus as thickness will result in magnification.

    Also, since it seems the progressive is "squeezed" into frame the optimum area to read distance Rx might be in the edger

  5. #5
    Rising Star
    Join Date
    Aug 2011
    Location
    Florida
    Occupation
    Dispensing Optician
    Posts
    50
    Years ago, when the Shamir rep would show me progressive plots of various progressive designs, almost all "short corridor" PALs would exhibit increased peripheral unwanted power in the distance. I would always caution patients who wanted to use a small B frame for progressive use due to this.

Thread Information

Users Browsing this Thread

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

Similar Threads

  1. Power variations above the distance reference point
    By ak47 in forum General Optics and Eyecare Discussion Forum
    Replies: 5
    Last Post: 08-30-2017, 01:43 PM
  2. Required Power at Specific Distance
    By D_Zab in forum Ophthalmic Optics
    Replies: 8
    Last Post: 10-13-2014, 10:06 AM
  3. Evaluate Near power or ADD power for Freeform products?
    By Delly in forum Progressive Lens Discussion Forum
    Replies: 3
    Last Post: 08-16-2011, 12:53 PM
  4. Distance and near total power and adaptation
    By drk in forum Progressive Lens Discussion Forum
    Replies: 7
    Last Post: 10-23-2009, 12:55 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
  •