Results 1 to 7 of 7

Thread: What is the minimum blank size for this Rx and PD?

  1. #1
    OptiBoard Apprentice
    Join Date
    Jan 2019
    Location
    New York
    Occupation
    Dispensing Optician
    Posts
    17

    What is the minimum blank size for this Rx and PD?

    What is the minimum blank size for this computer use prescription?

    OD: -0.75 -1.75 x 165
    OS: -1.75 -0.75 x 030

    ADD: +1.00 (INTERMEDIATE ADD)

    Patient's PD is 58

    Frame PD is 55, bridge is 18, and ED is 59 measured from inner to inner.

    Do I have to move the PD in for INT use?

  2. #2
    Master OptiBoarder optical24/7's Avatar
    Join Date
    May 2006
    Location
    Down on the Farm
    Occupation
    Dispensing Optician
    Posts
    5,809
    Power makes no difference unless you’re figuring how much you can *cheat* on decentration (altering the OC placement due to low prismatic value at 180). Frame PD - patients PD + Lens ED. With the above info:

    55 (eye size) + 18 (dbl) = 73 - 58 (patient PD) = 15 + 59 (ED) = 74. Some recommend going at least 1mm larger than the formula, so 75mm would be the minimum size stock lens for cut out.

    As far as PD comp for intermediate, usually 1mm for computer distance is good, but verify the distance of intended use and comp from there.

  3. #3
    Master OptiBoarder AngeHamm's Avatar
    Join Date
    Apr 2010
    Location
    Richmond, VA
    Occupation
    Optical Retail
    Posts
    2,370
    Quote Originally Posted by optical24/7 View Post
    Power makes no difference unless you’re figuring how much you can *cheat* on decentration (altering the OC placement due to low prismatic value at 180). Frame PD - patients PD + Lens ED.
    Power does​ make a difference insofar as minus lenses tend to come in 70mm blanks and plus in 65. But I knew what you meant; carry on...
    I'm Andrew Hamm and I approve this message.

  4. #4
    Master OptiBoarder optical24/7's Avatar
    Join Date
    May 2006
    Location
    Down on the Farm
    Occupation
    Dispensing Optician
    Posts
    5,809
    Quote Originally Posted by AngeHamm View Post
    Power does​ make a difference insofar as minus lenses tend to come in 70mm blanks and plus in 65. But I knew what you meant; carry on...

  5. #5
    Master OptiBoarder AngeHamm's Avatar
    Join Date
    Apr 2010
    Location
    Richmond, VA
    Occupation
    Optical Retail
    Posts
    2,370
    Also important to know: extreme OC heights can affect this data as well. That 65mm blank may cut out perfectly with a center OC, but raise it a few millimeters and you may not get cutout.
    I'm Andrew Hamm and I approve this message.

  6. #6
    OptiBoard Apprentice
    Join Date
    Jan 2019
    Location
    New York
    Occupation
    Dispensing Optician
    Posts
    17
    Quote Originally Posted by optical24/7 View Post
    Power makes no difference unless you’re figuring how much you can *cheat* on decentration (altering the OC placement due to low prismatic value at 180). Frame PD - patients PD + Lens ED. With the above info:

    55 (eye size) + 18 (dbl) = 73 - 58 (patient PD) = 15 + 59 (ED) = 74. Some recommend going at least 1mm larger than the formula, so 75mm would be the minimum size stock lens for cut out.

    As far as PD comp for intermediate, usually 1mm for computer distance is good, but verify the distance of intended use and comp from there.
    Do you have to add 1 or 2mm for certain lens type or prescription? Like if it's for reading glasses?

  7. #7
    Master OptiBoarder AngeHamm's Avatar
    Join Date
    Apr 2010
    Location
    Richmond, VA
    Occupation
    Optical Retail
    Posts
    2,370
    Quote Originally Posted by Optician53 View Post
    Do you have to add 1 or 2mm for certain lens type or prescription? Like if it's for reading glasses?
    RX shouldn't have anything to do with it. But I've found that some edgers, like the Santinelli LE1000 I'm currently using, are more "conservative" with their tracing. I add 1 or 2 because of that.
    I'm Andrew Hamm and I approve this message.

Thread Information

Users Browsing this Thread

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

Similar Threads

  1. Minimum Blank Size - Multifocals
    By lensmanmd in forum General Optics and Eyecare Discussion Forum
    Replies: 9
    Last Post: 08-07-2017, 03:09 PM
  2. Calculating minimum lens blank size
    By Just Me in forum Ophthalmic Optics
    Replies: 36
    Last Post: 10-15-2015, 12:13 PM
  3. Minimum blank size?
    By Don Gilman in forum General Optics and Eyecare Discussion Forum
    Replies: 8
    Last Post: 04-24-2012, 08:10 AM
  4. Extremely Large Minimum blank size
    By Gators in forum General Optics and Eyecare Discussion Forum
    Replies: 11
    Last Post: 10-19-2010, 08:56 PM
  5. minimum lens blank size
    By eyechicky in forum Ophthalmic Optics
    Replies: 7
    Last Post: 01-05-2005, 03:13 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
  •