Results 1 to 5 of 5

Thread: Define High Powered positive lens

  1. #1
    OptiBoard Novice
    Join Date
    Jan 2021
    Location
    England
    Occupation
    Dispensing Optician
    Posts
    1

    Define High Powered positive lens

    I am currently working through my coursework and on one question I have been asked: What do you understand by the term "High" power positive lenses and provide an example prescription which is suitable. State and explain two sources of evidence to support your answer.

    Now I understand that, lets say a +10.00 could be defined as a high positive power, but where does the "High" start from? would it be +5.00 due to requiring BVD based on the opticians act? I am really not too sure what to write in this answer, let alone find relevant examples.

    I have gone through a few books looking for information (Jalies bible and griffiths practical dispensing)

    I was hoping someone here would have any more info that I may be missing or overlooking.


    Thanks.

  2. #2
    Master OptiBoarder
    Join Date
    Feb 2013
    Location
    PA
    Occupation
    Dispensing Optician
    Posts
    1,607
    Interesting question. I think we can all pretty much agree what is considered "high power", but I have never seen actual documentation that states, "high power" starts at a specific power.

  3. #3
    Ghost in the OptiMachine Quince's Avatar
    Join Date
    Jan 2016
    Location
    Sebago ME
    Occupation
    Optical Laboratory Technician
    Posts
    1,172
    Citing sources for the term high-powered positive lens seems really strange. I would definitely consider this an subjective term. If I were going to try and pin it down (with reasoning) I would start at +3.50 because that is where the line in drawn for OTC readers in my region. We are not allowed to make and sell anything over a +3.25 without a prescription. This is also the range where I start strongly recommending thinner material options.
    Have I told you today how much I hate poly?

  4. #4
    Master OptiBoarder
    Join Date
    Mar 2010
    Location
    north of 49
    Occupation
    Dispensing Optician
    Posts
    3,002
    Quote Originally Posted by DanTheEyeMan View Post
    I am currently working through my coursework and on one question I have been asked: What do you understand by the term "High" power positive lenses and provide an example prescription which is suitable. State and explain two sources of evidence to support your answer.

    Now I understand that, lets say a +10.00 could be defined as a high positive power, but where does the "High" start from? would it be +5.00 due to requiring BVD based on the opticians act? I am really not too sure what to write in this answer, let alone find relevant examples.



    I have gone through a few books looking for information (Jalies bible and griffiths practical dispensing)

    I was hoping someone here would have any more info that I may be missing or overlooking.


    Thanks.
    Curtis D Benton, Jr and Robert C Welsh, in the book published as "Spectacles for Aphakia" suggested that high plus lenses differ from lower in 5 ways:


    1. Small variations in vertex are significant to the wearer.
    2. The five marginal lens abberations reach significant proportions.
    3. Pantoscopic angle changes create change to both the sphere and cylinder powers.
    4. Base curve selection is very critical.
    5. Thickness, in itself, creates special optical problems.

    Check on obtaining the book....it is well written.
    Eyes wide open

  5. #5
    One eye sees, the other feels OptiBoard Silver Supporter
    Join Date
    Jul 2002
    Location
    Wauwatosa Wi
    Occupation
    Dispensing Optician
    Posts
    5,458
    Quote Originally Posted by DanTheEyeMan View Post
    I am currently working through my coursework and on one question I have been asked: What do you understand by the term "High" power positive lenses and provide an example prescription which is suitable. State and explain two sources of evidence to support your answer.

    Now I understand that, lets say a +10.00 could be defined as a high positive power, but where does the "High" start from? would it be +5.00 due to requiring BVD based on the opticians act? I am really not too sure what to write in this answer, let alone find relevant examples.

    I have gone through a few books looking for information (Jalies bible and griffiths practical dispensing)

    I was hoping someone here would have any more info that I may be missing or overlooking.


    Thanks.
    I would draw the dividing line at about 8 D, where best form theory collapses above that power with plus power lenses.

    Best regards,

    Robert Martellaro
    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.



Thread Information

Users Browsing this Thread

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

Similar Threads

  1. Does high-powered frontside cylinder behave differently than backside?
    By Prentice Pro 9000 in forum General Optics and Eyecare Discussion Forum
    Replies: 17
    Last Post: 05-09-2017, 09:26 AM
  2. Aspheric and high powered lenses help
    By Student21 in forum Ophthalmic Optics
    Replies: 2
    Last Post: 07-01-2008, 01:40 AM
  3. Powered by vBulletin
    By RGC_man in forum Just Conversation
    Replies: 2
    Last Post: 12-03-2006, 09:39 PM
  4. Solar-powered Implant Could Restore Vision
    By Chris Ryser in forum General Optics and Eyecare Discussion Forum
    Replies: 0
    Last Post: 04-28-2006, 07:35 AM
  5. high quality prism, wedge, mirrors, lens, cylindrical lens etc
    By dhoptics in forum Optical Marketplace
    Replies: 0
    Last Post: 03-09-2005, 05:08 AM

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
  •